esprit engine rebuild
Discussion
I assume that the engine is turning over OK?
If you are getting absolutely no compression then it would suggest valves open.
Are you 100% sure the cam belt is on correctly? I think if it's a little out you wouldn't get the valves hitting the pistons but you might not get any compression.
Let us know how you get on.
If you are getting absolutely no compression then it would suggest valves open.
Are you 100% sure the cam belt is on correctly? I think if it's a little out you wouldn't get the valves hitting the pistons but you might not get any compression.
Let us know how you get on.
As Skeggysteve says, if you are getting no compression at all, then the valves must be open.
At risk of insulting your intelligence, are you sure that the cams are correctly timed and not 180 degrees out of phase? Are you taking the compression reading properly (cranking with throttle full open - if the throttls are closed, the engine won't be drawing in any air to compress!?).
At risk of insulting your intelligence, are you sure that the cams are correctly timed and not 180 degrees out of phase? Are you taking the compression reading properly (cranking with throttle full open - if the throttls are closed, the engine won't be drawing in any air to compress!?).
skeggy,sam thanx for the response, just to let you know i am a novice at this the problem being whoever had the car before me must have changed the belt on several occasions and ther are more than 1 timing marks on each sprocket so as for timing i have turned by hand and everything is free, and no i didnt have the throttle fully open, i thought i would get at least some sort of reading even though the throttle was closed even low, but absoulute nothing at all.
is there anyway i can check with the cam covers off for my cam settings. thanx again guys daz
is there anyway i can check with the cam covers off for my cam settings. thanx again guys daz
Darren,
I'm pretty sure that the Espirt N/A engine is the same as the Excel so have a look here for info on how to change a cambelt on a Excel.
Another place you could ask for help from is The Lotus Esprit Forum
Like Pistonheads they are a very good bunch have a read
I'm pretty sure that the Espirt N/A engine is the same as the Excel so have a look here for info on how to change a cambelt on a Excel.
Another place you could ask for help from is The Lotus Esprit Forum
Like Pistonheads they are a very good bunch have a read
I've had engines before where the timing pulleys have been swapped, so that the timing marks were not in the right place, so that might be worth checking.
Take the cam cover off, start at with piston at top dead centre and rotate the engine by hand, to ensure that the valves are being operated at sensible phasing to work with the 4 stroke principle.
4 stroke cycle is:
Revolution 1:
1 Induction: Piston descending from top dead centre; Inlet valves open, exhaust valve closed.
2 Compression: Piston coming back up the bore to compress the charge; both valves closed.
Revolution 2:
3 Power: Piston being driven down the bore; both valves closed
4 Exhaust: Piston coming back up the bore; exhaust valve open, inlet valve closed.
There's some overlap on the camshafts on high performance engines, so the change-over on the valves won't occur at exactly top dead centre/bottom dead centre with the above, but you'll get the idea.
You might also wish to check the other obvious posibility - that your compression gauge is fcuked! Particularly if it's one of the cheap 'Gunson' gauges with a rubber hose connecting the spark plug to the gauge (the hoses sometimes aren't air-tight). Can you feel air 'huffing' out of the open spark plug holes as the engine turns over?
If the cams are timed correctly but you've still genuinely got no compression on all cylinders, then it's either that the valve settings are grossly incorrect (so that the valves are never closing - check your valve-tappet clearances) or you have a major problem with piston sealing (you have fitted piston rings, right?
)
Take the cam cover off, start at with piston at top dead centre and rotate the engine by hand, to ensure that the valves are being operated at sensible phasing to work with the 4 stroke principle.
4 stroke cycle is:
Revolution 1:
1 Induction: Piston descending from top dead centre; Inlet valves open, exhaust valve closed.
2 Compression: Piston coming back up the bore to compress the charge; both valves closed.
Revolution 2:
3 Power: Piston being driven down the bore; both valves closed
4 Exhaust: Piston coming back up the bore; exhaust valve open, inlet valve closed.
There's some overlap on the camshafts on high performance engines, so the change-over on the valves won't occur at exactly top dead centre/bottom dead centre with the above, but you'll get the idea.
You might also wish to check the other obvious posibility - that your compression gauge is fcuked! Particularly if it's one of the cheap 'Gunson' gauges with a rubber hose connecting the spark plug to the gauge (the hoses sometimes aren't air-tight). Can you feel air 'huffing' out of the open spark plug holes as the engine turns over?
If the cams are timed correctly but you've still genuinely got no compression on all cylinders, then it's either that the valve settings are grossly incorrect (so that the valves are never closing - check your valve-tappet clearances) or you have a major problem with piston sealing (you have fitted piston rings, right?
)Edited by Sam_68 on Sunday 30th September 16:15
Darren
Go to the Jensen Healy preservation society web site they had an article in the newsletter a few months ago on the timing wheels, there are several marks, and they explain it all. Do a search on the engine and transmission forum.This is the best place for advice on 900 engines, and it is worth joining so you post questions.
Are you sure the wheels are on the right cam and the right way around. Do not run the engine with the timing out.
Go to the Jensen Healy preservation society web site they had an article in the newsletter a few months ago on the timing wheels, there are several marks, and they explain it all. Do a search on the engine and transmission forum.This is the best place for advice on 900 engines, and it is worth joining so you post questions.
Are you sure the wheels are on the right cam and the right way around. Do not run the engine with the timing out.
just like to say thanx to all that have responded to me.. i checked my gaps between the camshaft and the buckets and all the gaps where less or about 0.5 on the carb side, my problem is the tappets and the buckets went in the way they came out now ive phoned a couple of lotus dealers and one said that there should be a gasket and another said that there shouldnt be can anyone enlighten me. gasket between the cam carrier and the head. if i put a 3 mil gasket on it will take to the max height but there wasnt one on when i took it apart.
daz
daz
Darren
Gaps are .007 inch inlet, .011ex (7-11) easy to remember. Early cars had gaskets on the cam carriers, latter cars did not, I don't know any one who uses gasket, just a thin silicon seal.
What compression are you getting, My engine never runs high compression following a rebuild it takes about 100 km, I race my engine with around 250 bhp, (no turbo) and it comes down at regular intervals, I run a compression ratio of 11.2 so compression should be 165 psi, but when engine is first assembled it can be as low as 90, goes up as engine is run,
If you are unsure as to the valve timing go to this site and do a search, they have some pictures of the timing gear, inlet max opening is 108.
http://www.jensenhealey.com/forums/view_forum.php?...
You can reverse the cam wheels; make sure they are the right way around. I would be very surprised if the gaps are right reusing the same shims. It is hard to get the gaps right even with a good selection as carriers move each time you assemble. It is nearly impossible with a gasket (one reason not to use).
As I said do not run the engine if you are unsure of the engine timming, it is very expensive the engine is full interference, not only do the valves go into the piston space but they actually cross each other.
Your engine has nicolite liners, did you use the right rings? Don’t know what the difference is but I just had trouble getting rings to allow me to run Lotus Sunbeam pistons in a Eclat block, (long story on this) apparently the rings are a different hardness, and the Sunbeam one’s will not bed into the nicolite.
Kelvin
Gaps are .007 inch inlet, .011ex (7-11) easy to remember. Early cars had gaskets on the cam carriers, latter cars did not, I don't know any one who uses gasket, just a thin silicon seal.
What compression are you getting, My engine never runs high compression following a rebuild it takes about 100 km, I race my engine with around 250 bhp, (no turbo) and it comes down at regular intervals, I run a compression ratio of 11.2 so compression should be 165 psi, but when engine is first assembled it can be as low as 90, goes up as engine is run,
If you are unsure as to the valve timing go to this site and do a search, they have some pictures of the timing gear, inlet max opening is 108.
http://www.jensenhealey.com/forums/view_forum.php?...
You can reverse the cam wheels; make sure they are the right way around. I would be very surprised if the gaps are right reusing the same shims. It is hard to get the gaps right even with a good selection as carriers move each time you assemble. It is nearly impossible with a gasket (one reason not to use).
As I said do not run the engine if you are unsure of the engine timming, it is very expensive the engine is full interference, not only do the valves go into the piston space but they actually cross each other.
Your engine has nicolite liners, did you use the right rings? Don’t know what the difference is but I just had trouble getting rings to allow me to run Lotus Sunbeam pistons in a Eclat block, (long story on this) apparently the rings are a different hardness, and the Sunbeam one’s will not bed into the nicolite.
Kelvin
hi to everyone that answered my post, good news guys as it turned out it was the shims that needed an adjustment well a gasket between the cam carrier and the head seem to sort it at least its going after 4 weeks of stripping and rebuilding what a pain a big thanx too all you guys who answered, every one of you are worth your weight in gold i take my hat of to you,s no doubt in the near future i,ll be back on with an other problem.
darren
darren
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