Quote:
Originally Posted by maple_leaf_eh
Well, I might as well join the parade. 70-08876 has low compression and is a sonuvagun to start. It runs when going, but that is the tough part. The compression is low and very low.
My simple knowledge of engines says: sleeve the cylinders; change the cam to keep the valves closed longer; taller pistons; or mill the head or block to reduce the cylinder volume. No matter what, as Rob describes there are only so many modern wear elements on these engines. And we are stuck.
Now, I have a total of three blocks including the runner in the Jeep, a supposedly unused from rebuild engine and a third block with the cam and bottom end off. This third one is available for experiments if someone has good ideas.
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The tell tell signs back in the old days of low compression on these engines was that ether had to be used even on a cool fall day. These engines had what was known as an over square design; the pistons travel a very long stroke by today's standards, and were subject to wear.
Low compression on these engines was both common and not that bad to fix. If the oil pressure was still good, I used to do cheapy overhauls in the old days to fix the problem of worn cylinders/rings for a flat $400.
I would strip the crank and pistons from the engine, have the 4 cylinders bored over, and then re-assemble the engine with 4 new pistons and rings. Intake valves were never a problem, but occasionally there would be wear on the exhaust valve train which would also require attention.
I always found the engines to give about 15 to 20 thousand good miles, followed by about 15K tired miles, then require rebuild. Very low by today's standards.