jacko56

I am having a issue engine will not start when hot. It has been rebuilt due to previous owner overheated it. The issue is when its cold it has great compression 125-130psi when its warm it has a max of 60psi. I can get it to run but cranks forever. I tested it both dry and with oil in cylinders no change in the numbers. The engine has 20hrs on it. anyone have seen this before?
thanks for advice

JMS322

I believe normal compression on a stock 502 is about 150psi. The engine will NOT start with only 60 psi compression. It takes a min. of about 100 psi compression for a cylinder to fire. A leakdown test would be in order at this time to tell if the engine has a mechanical problem and would tell you why your compression is low.

353Formula

This morning I put air to the cylinders with rockers backed all the way off and I am getting air out the intake and also exhaust the valves are the issue Its just hard to believe that this engine only has 60hrs on it and was rebuilt by a very well known company. When it came off the dyno cranking compression was @180psi. I am also at the point where the injection system is getting thrown in the trash.