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Re-sleeve or not?
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Posted by htown16 (US)  on Wednesday, June 14, 2017 at 19:21
I took my cylinder barrel to a reputable shop to have it bored. They informed me the cylinder liners were flush with the top of the block and I should have it resleeved or risk head gasket leak. They said the liners should protrude .005. The engine had a new copper head gasket on it before I tore it down and had 140 psi compression. The engine is a bit of a bitsa with some 69 and 74 parts. The barrel may be a 69. Seems like a lot of work to have them resleeved just for the protrusion bit as otherwise the bores are in good shape and should clean up with a +20 overbore and hone.
Replies   :
Guys, think about it. When was the last time you saw a petrol engine with liner protrusion. Diesel have it due to higher operating compression, most refer to it as a cylinder fire band.
On triples, I run the barrel face flat, use copper gaskets and silver spray paint to seal them. If replacing a liner, I bore out the old one, heat the barrel, chill the new liner and drop in. Then place in a arbor press to hold the liner in place till the temperatures equalize. Then skim the surface, bore and hone then chamfer.
Re pillar studs, if stripped DO NOT use doubled up heli-coils, it won't work. You can get extra long inserts but does take some tracking down. Helicoil..
Timesert..
Oversize pillar stud.
I have always relied on the largest possible thread into soft alloy.
Alloy that has already given up on the original size thread.
Seems like a no brainer.. Time Fastener here in the US make an insert 3/8-16 x 1" which work really well to re-enforce the threaded hole for the pillars. And, while your at it, might as well replace the 40 odd year old pillar bolts too. Some years ago, I had 7 of them break all at once on one of the race bikes and two more broke on two different street motors. Both myself and P&M have replacements made from high strength steel alloy, 8740, (185,000 psi). Hi Charlie, cracked more barrels than stripped pillar studs, they don't need to be used if someone offered barrels and heads made from modern materials, along with through bolts, HT steel if a road bike, Titanium if turning out the Gee Gee's? Cheers, Dick. Through bolts, that's got my interest. Can you tell me more as I have always felt the pillar studs should of gone to the base of the cylinder block. Koota. Looks like Charlie B has the fix. Triple Tec & Tommy Gunn are the bomb!!!!! I would agree with Charlie's version, although I have not used that type of gasket.
I repaired a T160 which was suffering repeated head gasket failures. All three cylinder liners had dropped below the surface of the block. I simply had it machined flat, replaced no less than 8 pillar studs that had or were stripping due to people cranking the hell out of them to try and get a good seal. I used a copper head gasket which got coated with copper gasket spray, and also used aluminium rockerbox base gaskets with similar treatment.
We are now 3 years down the track and the owner is getting some serious miles from it...
Or, you could use a Multi-Layered-Steel gasket from Cometic. Jerry Liggett, Richard Peckett and myself have been using them with great success for the last few years and they are intended to use with liners that are not "proud" of the deck. Got a part number for that. Thanks Charlie for your advice. The Cometic gasket is on it's way here.
An alternative may be to remove sleeves take a skim of the block and replace sleeves.
Still not cheap but may be less costly than new sleeves. |
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