Low compression on three cylinders

100

Asked by keepitrunning Jun 21, 2014 at 03:54 PM about the 1975 Ford Ranchero

Question type: Maintenance & Repair

I just purchased this car and got it running.  It runs rough, misses and doesn't idle
properly. A compression check showed no 5 cylinder was only 30psi.  I added oil to
determine if it was valves or rings, I think I added too much oil.  I pulled the engine and
was pleasantly surprised to find the engine is in great shape, recently overhauled.  I
pulled the piston on no 5 and found the rings and cylinder in great shape.  I pulled the
exhaust valve and found it was NOT seating.  Since it has hydraulic lifters I didn't try to
adjust them.  Two other exhaust valve appear to not be seating.  I have lapped them in
and reassembled the head.  Now I am wondering if the valves are too long,  How does
on check that?  Any discussion would be appreciated.   Gary

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