David thank you for the information…
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The only ‘worry’ with not knowing the cause is a repeat event, Sawyer…
Odds are that the valve was bent for reasons not repeatable with proper procedures followed. It’s a bit odd that valve lash was to specs - a bent valve usually gives excessive lash. A light touch to the piston leaves no marks - like during high revs and weak spring. Also check valve guide clearance as per David - and he is also right with valve entanglement; if one cam is turned independently a valve may easily snag the other cam’s valve(s).
But it would be nice to know a reason; did you actually do anything with the engine before the compression test…?
Frank
xj6 85 Sov Europe (UK/NZ)
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I dont think I have seen anyone mention one of the most common (but not commonly mentioned) way to get a bent valve is is shortly after someone works on the car, a stray fastener goes thru the intake, and right on out the exhaust, leaving behind only a bent valve (if ur lucky)
Frank after installing the engine I tried to start it with no luck even with start fluid and spark testing which I had spark. the second thing I did was to check compression 1-2-3-5-6 had 155psi and #4 had 0 I checked it twice still same result. I checked valve clearance they were all good 12-14 I know which is strange but I check few times make sure. when I took engine apart I timed bottom end and cam shafts with my tool and they were bang on TDC and cams I turned engine and removed two bolts on each cam at bottom then turn engine to TDC and cam tool installed again. took out other two cam bolts removed the cams, them removed studs then head. I have a rebuilt head I’m putting on there does not seem to be any play in pistons and turning cam shaft back and forth no noises from bottom end…most of the shims were .099 notlike the engine that came out some shims were way less then .086 I found one shim .072. anything I should check has I’m waiting on parts. cheers
yes tony that happened to my spitfire after nut came of air cleaner. cheers mate
it happened to me on a Jag V12, and after a lot of trouble & expense by a Jag mechanic, unbelievably the same valve was still bent, and it still cost me to get fixed, last time my Jags ever went to a mechanic (by themselves).
A mechanic I know allowed a shop towel to be sucked thru the intake of a diesel, costing him a bunch
holly sht that’s one I never heard before shop towel getting sucked in.
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Certainly viable, Tony - but ‘common’…?
Frank
xj6 85 Sov Europe (UK/NZ)
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