I've been having trouble with my LO3 just resently. When I start it up it will idle really rough and when I open the throttle fuel will spray back out of the passenger side tbi bore. It isn't a constant spray. It seems as if one of the intake valves is staying open on the compression stroke. Does anyone know what TB bores feed what cylinders? That info would help me narrow my search to a mechanical problem in a few cylinders.

 

Each bore feeds both banks with a dual plane. I dont recall off the top of my head which feed which but youd probably have to follow them by eye. The best solution probably would be to do a compression check on all cylinders to make sure all is well. It could also be a misfire, or even a blown head gasket.

 

Well there is NO compression in the number 1 cylinder on the passenger side. When I loosened the rocker arm nuts to close the valves and reran the test, the compression jumped right up. I'm gonna try to shim the springs and see what happens.

 

Sounds like there is lots of gunk on the valve stem, or the valve stem is bent.

 

Ended up being a broken valve spring. Guess I have to call comp cams in the morning and see if its covered under warranty.

 

Was that one of comps springs? How much lift where you running?

 

Part Number 08-500-8
Engine Chevrolet
305ci-350ci
8cyl.
Grind Number CS XR258HR-12
Description
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Intake/Exhaust
Valve Adjustment 0/0
Gross Valve Lift 0.48/0.488
Duration 258/264

Lobe Separation 112
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Its the highest lift cam I could get with stock LO3 heads. Its pretty good for what it is.