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Boat pics
- Thread starter Lpgc
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I've only owned it a week so not yet, but I have LPG converted plenty boats in the past (especially stuff like the Mastercraft ski boats for ski clubs etc) and will likely be converting my boat if I keep it. Heh, you might have been kidding but LPG conversion of boats is quite popular ;-)
But first I want to get to the bottom of a knock from the engine, I don't know if it's from the top end or bottom end yet. This evening I removed the spark plugs, 7 were the same spec, one odd one. I'll be fitting all new plugs (and making sure the plugs that came out were correct spec), maybe leads and dizzy cap, fitting a new prop, not sure what else yet but I'll probably get that lot done then take it to the river again... Then maybe give it a strip down to make sure other engine related stuff isn't likely to break if I take it on the sea.
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There are Eboats for sure, the same company that built my boat make a 230hp electric bowrider boat... But that would probably take quite a while to charge at most moorings for small boats that have a 16amp shore power feed similar to the power feed at a campsite lol. Nowhere to charge at most boating places, nowhere on most rivers, lakes, lochs, certainly nowhere at places like Shell Island where they don't even have electric hook ups for campers. But they do have LPG refuelling at some marinas and it is possible to refuel with LPG anywhere by taking your own supply in bottles. I might also buy a campervan, which might have a storage area (like a large car boot) that I could stick a few 200 litre tanks in. I can't imagine anyone taking their own 15kw generator with them wherever they go, or in fact being allowed to use a generator on most camp sites or marinas. Even if they could, the cheapest way to run a generator would be from LPG anyway. ;-)
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Many years ago I worked for Shetland Boats near Bury St Edmunds and enjoyed my time there. I switched around a bit, from making the basic fibreglass hull to cutting and fitting carpets etc. I think they are still going strong. They had a very enthusiastic R&D dept. I wonder what their latest models are like when compared with the ones I helped to build?
Loving this boat thread, thanks Simon!
I'll dig out some pics of our old boat we had in North Holland many years ago, no where near as nice as yours Simon but we did have some fun on the canals!
I'll dig out some pics of our old boat we had in North Holland many years ago, no where near as nice as yours Simon but we did have some fun on the canals!
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I am led to believe that the old BMC "B series" is common amongst canal boat owners
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Cracking garden ornament, might be a bit shite in a transatlantic challenge?
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Water's got more drag factor than air.fck me Simon lol, V8 in that ickle boat!
Let's face it, we drive Elgrands, famed for the way they slip through the air effortlessly....a 3.5 V6 you say?... My, that seems overkill....
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Shetland boats are good on the sea and well built George, interesting that you used to work there!
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A few years after working for Shetland I moved back 'up north' and got together with a couple of mates to make our own 18 foot fishing boat out of fibreglass.
There was a bloke who lived about ten miles from me who had all the gear to make the hull and we just had to provide the labour. My experience at Shetland came in handy as I was able to show them the best way to do it.
One of my mates was a joiner so he took the boat home and we all helped him to fit it out.
I live on the north east coast so we only had to take the boat a mile and we were in the sea. It got well-used for a while but then our work patterns changed and we found it difficult to meet regularly. By then my joiner mate was into sea diving so he altered the stern to allow the boat to be used for this.
There was a bloke who lived about ten miles from me who had all the gear to make the hull and we just had to provide the labour. My experience at Shetland came in handy as I was able to show them the best way to do it.
One of my mates was a joiner so he took the boat home and we all helped him to fit it out.
I live on the north east coast so we only had to take the boat a mile and we were in the sea. It got well-used for a while but then our work patterns changed and we found it difficult to meet regularly. By then my joiner mate was into sea diving so he altered the stern to allow the boat to be used for this.
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That's great George! My dad wanted to get into boat building at one time, was talking about buying a mold and asked me if I wanted to set up with him but at the time I was more interested in other things. Do you spray the gelcoat into the mold first then go in with the fibreglass and wood?
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Too much water under the bridge since those days of fitness and brain power to remember much Simon.
I remember sweating while rollering the fibre glass strips on as hard as possible but that's about it.
I can still manage to remember a few of the days when we were pulling 10lb cod in one after the other. The days when we came back to shore with a couple of flatties are best forgotten.
I remember sweating while rollering the fibre glass strips on as hard as possible but that's about it.
I can still manage to remember a few of the days when we were pulling 10lb cod in one after the other. The days when we came back to shore with a couple of flatties are best forgotten.
- Messages
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- Reaction score
- 13,505
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- Location
- Mid Yorkshire
- First Name
- Simon
- Elgrand
- E51
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Update about my boat.
In above posts I said that there was a knock from the engine (that I wanted to put right). It also seemed down on power.
I found that the starboard side marine exhaust manifold (which is water cooled) was cracked and allowing 'raw water' (from the sea / river / lake / etc) into the exhaust system in a position above the engine from which it could run down into the engine when exhaust valves were open. I found this by both noticing an external crack on the manifold and because when I did a compression test with the manifold removed water was spat out of the spark plug holes.
Also during the compression test I found that several cylinders were down on compression, particularly cylinder 2.
So I knew I had to do some major work on the engine to sort it, which would at least involve removing the engine from the boat.
But before I could remove the engine from the boat (with the engine quite high up because the boat sits on a trailer which is quite high up) I had to first come up with some way of lifting it out of the boat... I first had to extend the height of my engine crane.
This is a pic of my engine crane after I'd modified it . It took quite a bit of box section steel from a local steel stockist and quite a lot of welding to modify the engine crane. Not only did I have to increase it's height but also it's base of support (width and length where it is supported by the ground) to prevent it toppling over at the new taller (less stable) height.
Then I could use the crane to remove the engine from the boat after first removing the outdrive, the exhaust manifolds and obviously all the piping and wiring connections between the boat and the engine. A guy who I've converted a lot of American RV's, a Merc and a Honda to LPG for, a very keen ex boater himself and a good customer who has become a good friend, gave me a hand during the craning out of the engine. I will be taking him for a ride on the boat at some point. I've also fixed his brother's LPG system on his RV, his brother Greg is an ex police inspector, I've become good mates with them both.
With the engine out and on the stand I started to strip it down.
And found scoring on cylinder 2 (the one with particularly low compression) and a bit of scoring on some of the other cylinders. But other cylinders look brand new, it has aftermarket new pistons fitted that are 0.040 oversize, so the engine has definitely been rebuilt recently. All the bearings (crank mains and conrod big ends) are in great condition and standard size, so there has been no work on the crank or big end bearings and it didn't need it during the last rebuild.
The scoring just about visible on cylinder 2 and it's piston. Very likely this was the reason for the low compression. Also the piston rings on cylinder 2 had lost the usual 'springiness' which points to an overheat problem. It seemed likely that the overheat problem was due to lack of lubrication due to water ingress from the failed marine exhaust manifolds but also my measurements pointed to the supposed 0.040 overbore only being a 0.039 overbore at the bottom end of the cylinders (tapered cylinder bores)... At this point I supposed that the engine problems could be due to a combination of lack of lubrication and too small piston ring gaps - If the rebuilder had assumed that the bore had been correctly opened out by 0.040 to 4.040" and assumed that the new rings (that he'll have fitted) were pre-gapped for a 4.040" bore he might just have fitted the rings without checking ring gaps at the critical point which is low down in the cylinder... Then if ring gap is only supposed to be (say) 0.012" (0.003" per inch of bore size and standard bore is 4") the ring gap would be even smaller on a bore that's 4.039" (0.001" undersize for a 0.040" overbore) and that 0.001" bore undersize would become 0.0031" undersize when it came to ring gap so ring gap would only be 0.0090" instead of 0.012"... Too small a ring gap leading to ring binding which would certainly cause bore scoring just by itself even on a car engine, but on a marine engine the gaps need to be a bit on the large side if anything because the block runs a bit cooler than a car engine whilst the pistons still run at close to normal temperature.
To get rid of the scratches in the cylinder bores I needed to either get the bores bored oversize to the next bigger oversize size (which would be +0.060" over, or 4.060" total) which is not really recommended because the cylinder wall thickness can become a bit thin with a +60 overbore and I didn't really want to go that route, or I could try honing the scratches out. Again I took meticulous measurements entering all the data into a spreadsheet, then began honing the cylinder myself starting with cylinder 2... Eventually ending up with 8 very nice looking cylinder bores, nicely honed with nice cross-hatching (to retain an oil film for piston rings to slide on), did some more meticulous measurements and was happy that (after all the honing) cylinder 2 was still in spec... Cyl 2 was now maybe 0.002" oversize (0.042" instead of 0.040") but that's OK. The next pic is cylinder 2 after I spent a lot of time honing it, it is now in great condition.
So now I knew I was still going to have an engine that was 0.040" over the standard 4" bore (nominal 4.040" bores as opposed to rebored nominal 4.060" bores) I bought a new set of pistons and piston rings which I imported from the US via the well known Rock Auto firm. Top marks to Rock Auto, I ordered pistons and rings on a Friday and they arrived on the Wednesday all the way from the US. The decent quality 8x hypereutectic pistons and upgraded ring set altogether including VAT and UK import tax (sorted by Rock Auto) came to less than £200 . I went with the same spec pistons as those I removed (which the last rebuilder used) but went with molly coated top ring and densile steel 2nd rings to help reduce the amount of time it would take the rings to seat on the newly honed cylinder bores, particularly important due to it being a boat (because you can't count on being able to run a boat flat out or at a certain or even different RPMs and engine loads like you can with a car, because with a car you can dictate gears, speeds, acceleration bursts, etc while with a boat you can't dictate river or sea conditions.
The pistons use a conrod that is pressed fitted onto the piston's gudgeon pin (Americans would call the gudgeon pin the wrist pin). I had to re-use the old conrods unless I wanted to increase costs by quite a lot by buying new conrods. Press fitted means that the small/little ends of conrods are an interference fit on the wrist/gudgeon pins that attach the conrods to the pistons, the gudgeon pins still 'float' inside each end of the pistons but they don't need anything to prevent them sliding out of the pistons because the conrods are interference fitted onto the middle of the gudgeon pins (as opposed to fully floating gudgeon pins which are secured at each end to prevent falling out of pistons or at least from contacting cylinder walls by e.g. circlips on the outside of gudgeon pins on the outside of pistons, and on which the 'little end' of the conrods isn't an interference fit on gudgeon pins but instead the gudgeon pin can rotate inside the little ends). For most applications including my application, press fit little ends on gudgeon pins is preferable to fully floating, plus press fit it cheaper, but more (much more) difficult to fit than fully floating. To remove press fit little ends from gudgeon pins (and then remove gudgeon pins from the piston / conrod assembly) requires heating the little end up then using a press to push the gudgeon pin out. If you try to do it without heat you might get 10 tons of pressure on the gudgeon pin while still the interference fit grip of the conrod on pin means it won't shift... so you have to heat it then press it, and even then the old piston will be ruined by the pressure of the press pushing the body of the piston against the steel of the press... If you don't want to ruin old pistons when removing gudgeon pins, even using heat, you need a special tool to support the piston as you press the pin out which I didn't have. But I wasn't worried about ruining old pistons, I just needed the conrods out of them to re-use with my new pistons. Then comes the really tricky bit... Having just removed a conrod from a piston and while it's little end is still hot you reheat the little end, while having a new piston ready to accept it's fitting with a new gudgeon pin partially inserted through one side of the piston... Then you put the hot little end into the piston and push the gudgeon pin through the little end of the rod and through the other side of the piston, to the correct depth (so the gudgeon pin is nicely centred in the piston). From removing the heat from the little end of the conrod to completing the insertion of the gudgeon pin through the piston / conrod assembly to the correct depth (so the pin is centred in the rod and piston centred on the pin) you only have around 2 seconds, or the rod will heat the pin and the rod itself will cool and the rod will be interference fitted on the pin... at which point you cannot move it without damaging the new piston, and to get a new piston involves importing from the US. Hence no pictures of removing pins from rods or refitting rods on new pistons.
Then when I'd successfully removed the 8 conrods from old pistons and fitted them on the new pistons (as explained above) I checked the gaps of the supposedly correctly pre-gapped new piston rings (1st and 2nd rings) by pushing them down into the lower end of the bores of respective cylinders using the new pistons. The only cylinder that I had to slightly open the gaps of the rings on (after honing) was cylinder 1... but good job I checked them all.
I didn't need to use Plastigauge on any of the bearings because they all looked in great condition.
This is the block (almost complete bottom end) after I'd refitted the camshaft, crankshaft, cam thrust plate, main bearings, rear oil seal and new pistons on old rods into it.
Some proper 'engineering' done in every sense of the word and I'm very pleased with how this is progressing, albeit slower than I'd have liked due to having to do my usual work (LPG converting vehicles), having a holiday, waiting for a few other bits not mentioned above (bolts etc) and having to adapt the engine crane.
The last engine rebuilder seems to have done everything by the book and for the best part this had paid off, but they seem to have taken a couple of shortcuts due to making assumptions, plus possibly (unless this developed later) not properly addressed the marine manifold leak problem. Undoubtedly rebuilt by a pro and so close to good but no cigar. I on the other hand know I have done everything meticulously, made no assumptions, taken very accurate measurements and finely adjusted e.g. ring gaps where necessary. I have also properly addressed the marine manifold problem. I don't have much concerns about this engine now running properly when it's all put back together and back in the boat.
Today I managed to get a bit of work done cleaning up the block to timing cover, timing cover to water pump, water pump to backplate and water pump to timing cover mating faces. I'll be fitting those parts with new gaskets soon, then I'll set about cleaning up the cylinder heads, stripping them, checking them, reinstall the flat hydraulic tappets, re-install the heads, re-install pushrods and rockers, etc.... Then I'll be up to long engine stage. Then I'll refit the inlet manifold and sump and fill it with oil but not fit the carb or distributor. Then I'll manually operate the oil pump whilst checking oil pressure and check for oil flow up pushrods and onto rockers. If that's all good I'll refit the inlet manifold, put the engine back in the boat, refit all the electrics and plumbing ,refit the exhaust manifold setups with new manifold and riser on the starboard side, refit the carb. Then all should be good.
I am yet undecided on whether to convert the engine to LPG for the run-in period or convert it later. LPG is far better for engines than petrol because petrol can wash the oil film from the cylinder bores, LPG won't do that even if the air/fuel mixture is extremely rich. A very rich air/fuel mixture of petrol could mean the very early death of this engine which is for most intents and purposes as good as brand new at this point. I dunno, I might just rig up a temporary LPG system for it using something like a simple Impco (gas carb) system, LPG won't cause oil wash from the cylinder bores regardless of even very rich (or lean) mixture so it could be a far better bet than chancing the old petrol carb doesn't have an issue that makes it provide very rich petrol mixture that then kills the newly built engine. Then maybe later I'll convert it properly... I have an idea to make a fully sequential fuel system on an engine that normally could not feature it... My idea involves fitting inductive pickups on each of the 8 spark plug leads that run between the distributor and spark plugs (the type of inductive pickup that an engine timing setup strobe light uses). Normally an engine like this (with carb and spark distributor) cannot feature sequential fuel injection because sequential fuel injection requires a cam sensor that they don't have. But a way of detecting the rotor arm position in the distributor would be just as good as a cam sensor on an older sequential fuel injection engine, hence my bespoke fuel injection system featuring inductive 'trigger' HT pulses to trigger the start point of each fuel injection pulse idea (for respective cylinders)... and I am capable of building the ECU and modifying the inlet manifold etc in such way to make the supposedly carb only engine run a sequential fuel injection system (petrol and/or LPG).
I was doing these kinds of mechanical and electrical things as a kid and I'm still doing them over 40 years later, I'm pretty good at them. But the things I'm really the best at are LPG conversions of vehicles and fault diagnosis of fuel injection systems.
In above posts I said that there was a knock from the engine (that I wanted to put right). It also seemed down on power.
I found that the starboard side marine exhaust manifold (which is water cooled) was cracked and allowing 'raw water' (from the sea / river / lake / etc) into the exhaust system in a position above the engine from which it could run down into the engine when exhaust valves were open. I found this by both noticing an external crack on the manifold and because when I did a compression test with the manifold removed water was spat out of the spark plug holes.
Also during the compression test I found that several cylinders were down on compression, particularly cylinder 2.
So I knew I had to do some major work on the engine to sort it, which would at least involve removing the engine from the boat.
But before I could remove the engine from the boat (with the engine quite high up because the boat sits on a trailer which is quite high up) I had to first come up with some way of lifting it out of the boat... I first had to extend the height of my engine crane.
This is a pic of my engine crane after I'd modified it
. It took quite a bit of box section steel from a local steel stockist and quite a lot of welding to modify the engine crane. Not only did I have to increase it's height but also it's base of support (width and length where it is supported by the ground) to prevent it toppling over at the new taller (less stable) height.Then I could use the crane to remove the engine from the boat after first removing the outdrive, the exhaust manifolds and obviously all the piping and wiring connections between the boat and the engine. A guy who I've converted a lot of American RV's, a Merc and a Honda to LPG for, a very keen ex boater himself and a good customer who has become a good friend, gave me a hand during the craning out of the engine. I will be taking him for a ride on the boat at some point. I've also fixed his brother's LPG system on his RV, his brother Greg is an ex police inspector, I've become good mates with them both.
With the engine out and on the stand I started to strip it down.
And found scoring on cylinder 2 (the one with particularly low compression) and a bit of scoring on some of the other cylinders. But other cylinders look brand new, it has aftermarket new pistons fitted that are 0.040 oversize, so the engine has definitely been rebuilt recently. All the bearings (crank mains and conrod big ends) are in great condition and standard size, so there has been no work on the crank or big end bearings and it didn't need it during the last rebuild.
The scoring just about visible on cylinder 2 and it's piston. Very likely this was the reason for the low compression. Also the piston rings on cylinder 2 had lost the usual 'springiness' which points to an overheat problem. It seemed likely that the overheat problem was due to lack of lubrication due to water ingress from the failed marine exhaust manifolds but also my measurements pointed to the supposed 0.040 overbore only being a 0.039 overbore at the bottom end of the cylinders (tapered cylinder bores)... At this point I supposed that the engine problems could be due to a combination of lack of lubrication and too small piston ring gaps - If the rebuilder had assumed that the bore had been correctly opened out by 0.040 to 4.040" and assumed that the new rings (that he'll have fitted) were pre-gapped for a 4.040" bore he might just have fitted the rings without checking ring gaps at the critical point which is low down in the cylinder... Then if ring gap is only supposed to be (say) 0.012" (0.003" per inch of bore size and standard bore is 4") the ring gap would be even smaller on a bore that's 4.039" (0.001" undersize for a 0.040" overbore) and that 0.001" bore undersize would become 0.0031" undersize when it came to ring gap so ring gap would only be 0.0090" instead of 0.012"... Too small a ring gap leading to ring binding which would certainly cause bore scoring just by itself even on a car engine, but on a marine engine the gaps need to be a bit on the large side if anything because the block runs a bit cooler than a car engine whilst the pistons still run at close to normal temperature.
To get rid of the scratches in the cylinder bores I needed to either get the bores bored oversize to the next bigger oversize size (which would be +0.060" over, or 4.060" total) which is not really recommended because the cylinder wall thickness can become a bit thin with a +60 overbore and I didn't really want to go that route, or I could try honing the scratches out. Again I took meticulous measurements entering all the data into a spreadsheet, then began honing the cylinder myself starting with cylinder 2... Eventually ending up with 8 very nice looking cylinder bores, nicely honed with nice cross-hatching (to retain an oil film for piston rings to slide on), did some more meticulous measurements and was happy that (after all the honing) cylinder 2 was still in spec... Cyl 2 was now maybe 0.002" oversize (0.042" instead of 0.040") but that's OK. The next pic is cylinder 2 after I spent a lot of time honing it, it is now in great condition.
So now I knew I was still going to have an engine that was 0.040" over the standard 4" bore (nominal 4.040" bores as opposed to rebored nominal 4.060" bores) I bought a new set of pistons and piston rings which I imported from the US via the well known Rock Auto firm. Top marks to Rock Auto, I ordered pistons and rings on a Friday and they arrived on the Wednesday all the way from the US. The decent quality 8x hypereutectic pistons and upgraded ring set altogether including VAT and UK import tax (sorted by Rock Auto) came to less than £200 . I went with the same spec pistons as those I removed (which the last rebuilder used) but went with molly coated top ring and densile steel 2nd rings to help reduce the amount of time it would take the rings to seat on the newly honed cylinder bores, particularly important due to it being a boat (because you can't count on being able to run a boat flat out or at a certain or even different RPMs and engine loads like you can with a car, because with a car you can dictate gears, speeds, acceleration bursts, etc while with a boat you can't dictate river or sea conditions.
The pistons use a conrod that is pressed fitted onto the piston's gudgeon pin (Americans would call the gudgeon pin the wrist pin). I had to re-use the old conrods unless I wanted to increase costs by quite a lot by buying new conrods. Press fitted means that the small/little ends of conrods are an interference fit on the wrist/gudgeon pins that attach the conrods to the pistons, the gudgeon pins still 'float' inside each end of the pistons but they don't need anything to prevent them sliding out of the pistons because the conrods are interference fitted onto the middle of the gudgeon pins (as opposed to fully floating gudgeon pins which are secured at each end to prevent falling out of pistons or at least from contacting cylinder walls by e.g. circlips on the outside of gudgeon pins on the outside of pistons, and on which the 'little end' of the conrods isn't an interference fit on gudgeon pins but instead the gudgeon pin can rotate inside the little ends). For most applications including my application, press fit little ends on gudgeon pins is preferable to fully floating, plus press fit it cheaper, but more (much more) difficult to fit than fully floating. To remove press fit little ends from gudgeon pins (and then remove gudgeon pins from the piston / conrod assembly) requires heating the little end up then using a press to push the gudgeon pin out. If you try to do it without heat you might get 10 tons of pressure on the gudgeon pin while still the interference fit grip of the conrod on pin means it won't shift... so you have to heat it then press it, and even then the old piston will be ruined by the pressure of the press pushing the body of the piston against the steel of the press... If you don't want to ruin old pistons when removing gudgeon pins, even using heat, you need a special tool to support the piston as you press the pin out which I didn't have. But I wasn't worried about ruining old pistons, I just needed the conrods out of them to re-use with my new pistons. Then comes the really tricky bit... Having just removed a conrod from a piston and while it's little end is still hot you reheat the little end, while having a new piston ready to accept it's fitting with a new gudgeon pin partially inserted through one side of the piston... Then you put the hot little end into the piston and push the gudgeon pin through the little end of the rod and through the other side of the piston, to the correct depth (so the gudgeon pin is nicely centred in the piston). From removing the heat from the little end of the conrod to completing the insertion of the gudgeon pin through the piston / conrod assembly to the correct depth (so the pin is centred in the rod and piston centred on the pin) you only have around 2 seconds, or the rod will heat the pin and the rod itself will cool and the rod will be interference fitted on the pin... at which point you cannot move it without damaging the new piston, and to get a new piston involves importing from the US. Hence no pictures of removing pins from rods or refitting rods on new pistons.
Then when I'd successfully removed the 8 conrods from old pistons and fitted them on the new pistons (as explained above) I checked the gaps of the supposedly correctly pre-gapped new piston rings (1st and 2nd rings) by pushing them down into the lower end of the bores of respective cylinders using the new pistons. The only cylinder that I had to slightly open the gaps of the rings on (after honing) was cylinder 1... but good job I checked them all.
I didn't need to use Plastigauge on any of the bearings because they all looked in great condition.
This is the block (almost complete bottom end) after I'd refitted the camshaft, crankshaft, cam thrust plate, main bearings, rear oil seal and new pistons on old rods into it.
Some proper 'engineering' done in every sense of the word and I'm very pleased with how this is progressing, albeit slower than I'd have liked due to having to do my usual work (LPG converting vehicles), having a holiday, waiting for a few other bits not mentioned above (bolts etc) and having to adapt the engine crane.
The last engine rebuilder seems to have done everything by the book and for the best part this had paid off, but they seem to have taken a couple of shortcuts due to making assumptions, plus possibly (unless this developed later) not properly addressed the marine manifold leak problem. Undoubtedly rebuilt by a pro and so close to good but no cigar. I on the other hand know I have done everything meticulously, made no assumptions, taken very accurate measurements and finely adjusted e.g. ring gaps where necessary. I have also properly addressed the marine manifold problem. I don't have much concerns about this engine now running properly when it's all put back together and back in the boat.
Today I managed to get a bit of work done cleaning up the block to timing cover, timing cover to water pump, water pump to backplate and water pump to timing cover mating faces. I'll be fitting those parts with new gaskets soon, then I'll set about cleaning up the cylinder heads, stripping them, checking them, reinstall the flat hydraulic tappets, re-install the heads, re-install pushrods and rockers, etc.... Then I'll be up to long engine stage. Then I'll refit the inlet manifold and sump and fill it with oil but not fit the carb or distributor. Then I'll manually operate the oil pump whilst checking oil pressure and check for oil flow up pushrods and onto rockers. If that's all good I'll refit the inlet manifold, put the engine back in the boat, refit all the electrics and plumbing ,refit the exhaust manifold setups with new manifold and riser on the starboard side, refit the carb. Then all should be good.
I am yet undecided on whether to convert the engine to LPG for the run-in period or convert it later. LPG is far better for engines than petrol because petrol can wash the oil film from the cylinder bores, LPG won't do that even if the air/fuel mixture is extremely rich. A very rich air/fuel mixture of petrol could mean the very early death of this engine which is for most intents and purposes as good as brand new at this point. I dunno, I might just rig up a temporary LPG system for it using something like a simple Impco (gas carb) system, LPG won't cause oil wash from the cylinder bores regardless of even very rich (or lean) mixture so it could be a far better bet than chancing the old petrol carb doesn't have an issue that makes it provide very rich petrol mixture that then kills the newly built engine. Then maybe later I'll convert it properly... I have an idea to make a fully sequential fuel system on an engine that normally could not feature it... My idea involves fitting inductive pickups on each of the 8 spark plug leads that run between the distributor and spark plugs (the type of inductive pickup that an engine timing setup strobe light uses). Normally an engine like this (with carb and spark distributor) cannot feature sequential fuel injection because sequential fuel injection requires a cam sensor that they don't have. But a way of detecting the rotor arm position in the distributor would be just as good as a cam sensor on an older sequential fuel injection engine, hence my bespoke fuel injection system featuring inductive 'trigger' HT pulses to trigger the start point of each fuel injection pulse idea (for respective cylinders)... and I am capable of building the ECU and modifying the inlet manifold etc in such way to make the supposedly carb only engine run a sequential fuel injection system (petrol and/or LPG).
I was doing these kinds of mechanical and electrical things as a kid and I'm still doing them over 40 years later, I'm pretty good at them. But the things I'm really the best at are LPG conversions of vehicles and fault diagnosis of fuel injection systems.
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Update about my boat.
In above posts I said that there was a knock from the engine (that I wanted to put right). It also seemed down on power.
I found that the starboard side marine exhaust manifold (which is water cooled) was cracked and allowing 'raw water' (from the sea / river / lake / etc) into the exhaust system in a position above the engine from which it could run down into the engine when exhaust valves were open. I found this by both noticing an external crack on the manifold and because when I did a compression test with the manifold removed water was spat out of the spark plug holes.
Also during the compression test I found that several cylinders were down on compression, particularly cylinder 2.
So I knew I had to do some major work on the engine to sort it, which would at least involve removing the engine from the boat.
But before I could remove the engine from the boat (with the engine quite high up because the boat sits on a trailer which is quite high up) I had to first come up with some way of lifting it out of the boat... I first had to extend the height of my engine crane.
This is a pic of my engine crane after I'd modified it
View attachment 93376
Then I could use the crane to remove the engine from the boat after first removing the outdrive, the exhaust manifolds and obviously all the piping and wiring connections between the boat and the engine. A guy who I've converted a lot of American RV's, a Merc and a Honda to LPG for, a very keen ex boater himself and a good customer who has become a good friend, gave me a hand during the craning out of the engine. I will be taking him for a ride on the boat at some point. I've also fixed his brother's LPG system on his RV, his brother Greg is an ex police inspector, I've become good mates with them both.
View attachment 93377
With the engine out and on the stand I started to strip it down.
View attachment 93378
View attachment 93379
And found scoring on cylinder 2 (the one with particularly low compression) and a bit of scoring on some of the other cylinders. But other cylinders look brand new, it has aftermarket new pistons fitted that are 0.040 oversize, so the engine has definitely been rebuilt recently. All the bearings (crank mains and conrod big ends) are in great condition and standard size, so there has been no work on the crank or big end bearings and it didn't need it during the last rebuild.
The scoring just about visible on cylinder 2 and it's piston. Very likely this was the reason for the low compression. Also the piston rings on cylinder 2 had lost the usual 'springiness' which points to an overheat problem. It seemed likely that the overheat problem was due to lack of lubrication due to water ingress from the failed marine exhaust manifolds but also my measurements pointed to the supposed 0.040 overbore only being a 0.039 overbore at the bottom end of the cylinders (tapered cylinder bores)... At this point I supposed that the engine problems could be due to a combination of lack of lubrication and too small piston ring gaps - If the rebuilder had assumed that the bore had been correctly opened out by 0.040 to 4.040" and assumed that the new rings (that he'll have fitted) were pre-gapped for a 4.040" bore he might just have fitted the rings without checking ring gaps at the critical point which is low down in the cylinder... Then if ring gap is only supposed to be (say) 0.012" (0.003" per inch of bore size and standard bore is 4") the ring gap would be even smaller on a bore that's 4.039" (0.001" undersize for a 0.040" overbore) and that 0.001" bore undersize would become 0.0031" undersize when it came to ring gap so ring gap would only be 0.0090" instead of 0.012"... Too small a ring gap leading to ring binding which would certainly cause bore scoring just by itself even on a car engine, but on a marine engine the gaps need to be a bit on the large side if anything because the block runs a bit cooler than a car engine whilst the pistons still run at close to normal temperature.
View attachment 93380
View attachment 93381
To get rid of the scratches in the cylinder bores I needed to either get the bores bored oversize to the next bigger oversize size (which would be +0.060" over, or 4.060" total) which is not really recommended because the cylinder wall thickness can become a bit thin with a +60 overbore and I didn't really want to go that route, or I could try honing the scratches out. Again I took meticulous measurements entering all the data into a spreadsheet, then began honing the cylinder myself starting with cylinder 2... Eventually ending up with 8 very nice looking cylinder bores, nicely honed with nice cross-hatching (to retain an oil film for piston rings to slide on), did some more meticulous measurements and was happy that (after all the honing) cylinder 2 was still in spec... Cyl 2 was now maybe 0.002" oversize (0.042" instead of 0.040") but that's OK. The next pic is cylinder 2 after I spent a lot of time honing it, it is now in great condition.
View attachment 93382
So now I knew I was still going to have an engine that was 0.040" over the standard 4" bore (nominal 4.040" bores as opposed to rebored nominal 4.060" bores) I bought a new set of pistons and piston rings which I imported from the US via the well known Rock Auto firm. Top marks to Rock Auto, I ordered pistons and rings on a Friday and they arrived on the Wednesday all the way from the US. The decent quality 8x hypereutectic pistons and upgraded ring set altogether including VAT and UK import tax (sorted by Rock Auto) came to less than £200 . I went with the same spec pistons as those I removed (which the last rebuilder used) but went with molly coated top ring and densile steel 2nd rings to help reduce the amount of time it would take the rings to seat on the newly honed cylinder bores, particularly important due to it being a boat (because you can't count on being able to run a boat flat out or at a certain or even different RPMs and engine loads like you can with a car, because with a car you can dictate gears, speeds, acceleration bursts, etc while with a boat you can't dictate river or sea conditions.
The pistons use a conrod that is pressed fitted onto the piston's gudgeon pin (Americans would call the gudgeon pin the wrist pin). I had to re-use the old conrods unless I wanted to increase costs by quite a lot by buying new conrods. Press fitted means that the small/little ends of conrods are an interference fit on the wrist/gudgeon pins that attach the conrods to the pistons, the gudgeon pins still 'float' inside each end of the pistons but they don't need anything to prevent them sliding out of the pistons because the conrods are interference fitted onto the middle of the gudgeon pins (as opposed to fully floating gudgeon pins which are secured at each end to prevent falling out of pistons or at least from contacting cylinder walls by e.g. circlips on the outside of gudgeon pins on the outside of pistons, and on which the 'little end' of the conrods isn't an interference fit on gudgeon pins but instead the gudgeon pin can rotate inside the little ends). For most applications including my application, press fit little ends on gudgeon pins is preferable to fully floating, plus press fit it cheaper, but more (much more) difficult to fit than fully floating. To remove press fit little ends from gudgeon pins (and then remove gudgeon pins from the piston / conrod assembly) requires heating the little end up then using a press to push the gudgeon pin out. If you try to do it without heat you might get 10 tons of pressure on the gudgeon pin while still the interference fit grip of the conrod on pin means it won't shift... so you have to heat it then press it, and even then the old piston will be ruined by the pressure of the press pushing the body of the piston against the steel of the press... If you don't want to ruin old pistons when removing gudgeon pins, even using heat, you need a special tool to support the piston as you press the pin out which I didn't have. But I wasn't worried about ruining old pistons, I just needed the conrods out of them to re-use with my new pistons. Then comes the really tricky bit... Having just removed a conrod from a piston and while it's little end is still hot you reheat the little end, while having a new piston ready to accept it's fitting with a new gudgeon pin partially inserted through one side of the piston... Then you put the hot little end into the piston and push the gudgeon pin through the little end of the rod and through the other side of the piston, to the correct depth (so the gudgeon pin is nicely centred in the piston). From removing the heat from the little end of the conrod to completing the insertion of the gudgeon pin through the piston / conrod assembly to the correct depth (so the pin is centred in the rod and piston centred on the pin) you only have around 2 seconds, or the rod will heat the pin and the rod itself will cool and the rod will be interference fitted on the pin... at which point you cannot move it without damaging the new piston, and to get a new piston involves importing from the US. Hence no pictures of removing pins from rods or refitting rods on new pistons.
Then when I'd successfully removed the 8 conrods from old pistons and fitted them on the new pistons (as explained above) I checked the gaps of the supposedly correctly pre-gapped new piston rings (1st and 2nd rings) by pushing them down into the lower end of the bores of respective cylinders using the new pistons. The only cylinder that I had to slightly open the gaps of the rings on (after honing) was cylinder 1... but good job I checked them all.
I didn't need to use Plastigauge on any of the bearings because they all looked in great condition.
This is the block (almost complete bottom end) after I'd refitted the camshaft, crankshaft, cam thrust plate, main bearings, rear oil seal and new pistons on old rods into it.
View attachment 93383
View attachment 93384
Some proper 'engineering' done in every sense of the word and I'm very pleased with how this is progressing, albeit slower than I'd have liked due to having to do my usual work (LPG converting vehicles), having a holiday, waiting for a few other bits not mentioned above (bolts etc) and having to adapt the engine crane.
Today I managed to get a bit of work done cleaning up the block to timing cover, timing cover to water pump, water pump to backplate and water pump to timing cover mating faces. I'll be fitting those parts with new gaskets soon, then I'll set about cleaning up the cylinder heads, stripping them, checking them, reinstall the cam follower, re-install the heads, re-install pushrods and rockers, etc.... Then I'll be up to long engine stage. Then I'll refit the inlet manifold and sump and fill it with oil but not fit the carb or distributor. Then I'll manually operate the oil pump whilst checking oil pressure and check for oil flow up pushrods and onto rockers. If that's all good I'll refit the inlet manifold, put the engine back in the boat, refit all the electrics and plumbing ,refit the exhaust manifold setup with new manifold and riser on the starboard side, refit the carb. Then all should be good.
I am yet undecided on whether to convert the engine to LPG for the run-in period or convert it later. LPG is far better for engines than petrol because petrol can wash the oil film from the cylinder bores, LPG won't do that even if the air/fuel mixture is extremely rich. A very rich air/fuel mixture of petrol could mean the very early death of this engine which is for most intents and purposes as good as brand new at this point. I dunno, I might just rig up a temporary LPG system for it using something like a simple Impco (gas carb) system. Then maybe later I'll convert it properly... I have an idea to make a fully sequential fuel system on an engine that normally could not feature it... My idea involves fitting inductive pickups on each of the 8 spark plug leads that run between the distributor and spark plugs. Normally an engine like this (with carb and spark distributor) cannot feature sequential fuel injection because sequential fuel injection requires a cam sensor that they don't have. But a way of detecting the rotor arm position in the distributor would be just as good as a cam sensor on an older sequential fuel injection engine.
Impressive stuff buddy!
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That's proper cool
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Top work there mate.
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The new fuel injection system sounds good Simon. It should make the engine more responsive and improve fuel consumption - and it doesn't sound as though it will be expensive to do.
How sensitive does it need to be? Will you be able to put the inductive pick-ups anywhere along each spark plug lead or will you have to experiment a bit?
How sensitive does it need to be? Will you be able to put the inductive pick-ups anywhere along each spark plug lead or will you have to experiment a bit?
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I expect to have to experiment a bit George, too close to the distributor where the plug leads are all bunched up in close proximity to each other could give some cross-talk with the inductive sensor that's on one plug lead also picking up inducted signals from adjacent leads. Other sensors would be either a map sensor or maf sensor and a tps sensor. I have in the past made my own tps sensors for use on carb engines just using a simple potentiometer driven from the end of the throttle arm via a bit of rubber pipe that acts as a CV joint, simple but effective and accurate. I don't need the ECU for such injection system to be anything complicated or even programmable because I can use it's output as input for an LPG slave ECU and the LPG slave ECU can handle the mapping, the peak and hold control for injectors, the temperature compensation etc. All the simple ECU needs to be capable of is generating a pulse on each injector output ABCDEFGH when it receives an induction pulse from respective plug wires 12345678 with the pulse length of A>H depending on map or maf reading.... pulse length would need to be around 1ms at map of 0.1bar (not that the engine will ever see 0.1bar map) rising to around 12ms with map at 1bar. If I wanted I could later upgrade the simple ECU to feature closed loop control by programming it to decrease it's output pulse lengths for rich lambda signals and vice/versa, but it'd be a bit more complicated than that because the rate of change of pulse length needs to be relative to rpm and to a lesser extent to map. Can't really very easily add a lambda sensor to the marine engine with it's water cooled exhaust manifold setup though... it would work for a while but when the engine was shut off if any steam/condensation got to the sensor it would soon cause the sensor to fail.
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Decided to buy a full set of new cylinder head bolts for it, plus I needed a set of dowels to locate the cylinder head gasket before I could refit the heads. Seems the only place in the UK I could get either/both from was Rock Auto but I still couldn't get just the dowels, had to buy a 'kit' that included dowels, carb fuel pump eccentric, cam thrust plate and cam thrust plate retaining bolts. Wish I'd known earlier because I bought a set of cam retainer bolts from the US just before the start of my holiday which arrived just after my return from holiday which cost me £12 for 2 little bolts!
Had the cylinder heads skimmed at a local machine shop to get rid of a bit of pitting I was concerned about around the fire ring area.
I decided to remove the valves to check valve stem clearances (using the obvious and simple method of trying to rock them sideways in the cylinder head stem guides) and thought that while I'd got the valve springs off I might as well check the valve / seat mating faces and re-lap them. Today I had a bit of time to this but I only got as far as doing 6 valves on the port side head (cylinders 5 to 8) that didn't have any low compression issues anyway.... Yet still (even though there didn't seem to be any compression issues on the bank of cylinders that the head I worked on today came off) I had (and still have) a slight concern about one of the exhaust valves not seeming to lap in very well, the other 5 valves and seats I've worked on today have a great bright finish but this one exhaust valve (so far) has a few spots that remain looking a bit like pit marks (even though I can't feel anything) after a great deal of lapping. As said there were no issues with compression with this head but still I'd feel better if I got that valve mating face nice and bright.
Had the cylinder heads skimmed at a local machine shop to get rid of a bit of pitting I was concerned about around the fire ring area.
I decided to remove the valves to check valve stem clearances (using the obvious and simple method of trying to rock them sideways in the cylinder head stem guides) and thought that while I'd got the valve springs off I might as well check the valve / seat mating faces and re-lap them. Today I had a bit of time to this but I only got as far as doing 6 valves on the port side head (cylinders 5 to 8) that didn't have any low compression issues anyway.... Yet still (even though there didn't seem to be any compression issues on the bank of cylinders that the head I worked on today came off) I had (and still have) a slight concern about one of the exhaust valves not seeming to lap in very well, the other 5 valves and seats I've worked on today have a great bright finish but this one exhaust valve (so far) has a few spots that remain looking a bit like pit marks (even though I can't feel anything) after a great deal of lapping. As said there were no issues with compression with this head but still I'd feel better if I got that valve mating face nice and bright.
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