Just thinking this through:
Any vendor recommendations for Cometic gaskets? I want to buy Cometic head, oil pan, and valve-cover gaskets.
Thanks!
Dave,
Since you plan on removing the sump also, maybe you want to try and put the crank in the position I mentioned where the rear lobe is out of the way and then lock the cam timing gears there instead? That way you shouldn’t need to turn the crank again with everything apart. I’d probably start with the sump removal step because that way if you need to adjust the crank one way or the other to facilitate removal, the timing will still be all connected and it should all slip back together easily later on.
Before you pull the head, you might want to loosen the cam bearing caps so that the valves are closed. Less risk of bending a valve that way. If you don’t then be sure to not set it down on a flat surface.
I got mine from Terry’s but you may be able to order them directly from the Cometic company at this point. You’re going to need to CC the head to come up with the correct gasket thickness. It isn’t something to guess at. I believe Ray had a good post about that process and a spreadsheet to work out the calculations. I’ve totally spaced out about how that’s done as it was done a long time ago. I can’t recall whether it has to happen with the head on or the head off. You’ll want to figure this out before removing it.
.
Thanks Erica. I was painting myself into a corner.
I agree: Position rear cylinder, drop sump, then loosen cams, and pull head. I imagine the head including intake, carbs and exhaust is rather unwieldy!
You’re right about CC’ing the cylinders. I’ve done it before, and IIRC, head must be off, so I’m good.
Yep, It’s going to weigh a ton with both intake and exhaust attached. The only real upside is if you have a crane you can loop a strap under the manifolds and crank it up. But once you have it off the head studs it’s going to be rough to move, but doable if you have extra hands available. It should be easy enough to lay it upside down on wood blocks and level it so you can CC it.
It isn’t too awful to remove the intake as a unit and then replace it though, and you can use the great Cometic intake gasket upon reassembly. Pick your poison I guess.
Well, the 8 11/16" trick doesn’t seem to work for me. In the photo, piston #1 (rear) is at bottom of stroke, yet the measuring rod isn’t anywhere near the threads. The 3.8L engine has a 4.2" stroke, so the 8" number is questionable. Yes, my engine has original 9:1 pistons, it’s just that the gold paint has worn off the head.
I will split the difference between top and bottom of stroke, and will submit a revised yardstick.
Dave,
Apologies, it’s been many years since trying this. I measured from the wrong end of the probe. Try 4 9/16" instead.
I no longer have the measurement but it was just slightly before BDC.
Bob
889076
Plymouth, Mi.
I measured the halfway point as 3 7/8". Thus, 4 9/16" would be “slightly before BDC”. I’ll try that.
All good, no worries, we’ll figure it out. Thanks!
Dave
Erica, I would suggest that you go back and edit your posting above and correct the measurement so that sometime in the future, someone searching the archives doesn’t come across the wrong info.
Good idea! So nice to be able to edit now.
Got the oil pan off. Shoe/rubbing block is definitely not attached. I’ll have to muck around in the oil pan to find it. Bottom chain is very slack.
I pulled exhaust manifolds off, and will do likewise with carbs. Then, off with its head, followed by front cover removal.
Thanks to everyone for their guidance. No haters on the silicone - that was from 30 years ago.
Dave
Count yourself lucky as I had a tensioner come apart a number of years ago and the chain hooked on one of the guides and actually tore it off. There was some fairly major damage and as I recall I replaced, besides the guide at least one sprocket and as there was a bent valve I put on my spare head and haven’t gotten around to rebuilding the original yet.
Bob
889076
Plymouth, Mi.
N O T H I N G wrong with silicone, properly used.
Loooong ago, I deleted the thin paper gaskets for the timing chain cover with silicone. It seals MUCH better, and, as witnessed by your 30-year old ones, is durable.
Good deal, thankfully the shoe is too large to get sucked up so it’s got to be in the pan. If you want to avoid the silly cone moving forward I highly recommend the Cometic sump seal. My pan has been on and off 3 times using the same gasket, still no leaks. I think the only place I didn’t use those things was on the timing cover as I was afraid the extra thickness might be a problem.
Nord-lock washers on those sump bolts also prevents them from loosening without having to use locktite.
Dave,
Sometimes the dampers snap off as a result of the tensioner going for a ride into the sump due to excess wear in the chain. Then the chain slaps the dampers until they snap off particularly the long one on the right.
Just a recap. With everyone’s help, I dropped the oil pan, pulled the head, and removed the front cover. The tensioner had fallen out of the housing, flipped around, and wedged itself behind the housing, without causing any noticeable damage. Whew, I feel I dodged a bullet.
Getting ready to CC the head and block to calculate correct head gasket to provide a true 9:1 compression ratio (using Ray’s spreadsheet). I’ll just sign my next paycheck over to Cometic for every E-type gasket I can find.
Dave
Buy a lottery ticket! Do it now while your luck is still in effect.
Any ideas how it happened yet? I see a reasonable amount of wear in the rubber shoe. Is the chain also stretched and was it new when the tensioner went in? How many miles driven? Can you at this point move the chain to the side and slip it back into place? (for science not for keepsies). I’m wondering how common this failure is and whether there might have been some secondary contributor to it happening. Is this an old stock tensioner or aftermarket?
If the damper on the lower chain is set incorrectly, it can cause the tensioner to escape a lot sooner than it might do. Can’t see from the photos if it’s thats case in this instance.
Nigel
Where’s the spring and the ratchet thingie?
The spring had migrated to the upper chain eccentric. I tied on the string to keep it from falling before I took the photo. It just lifted out. It wasn’t chewed up, but had been stretched quite a bit.
I’ll have more info tomorrow when I pull out the timing chain assembly, but overall it could have been a lot worse.
