10-05-2012, 11:42 PM
Originally Posted by DoubleVision
I think it can be done by getting the cam specs and checking it with a dial indicator while verifing the piston is at top dead center. However I suspect the issue is elsewhere. For your compression ratio figures to be varied like that you either didn't perform the test correctly, or it's got a bore or ring issue or it's got some partially burned valves. You said the engine has been overhauled. How many miles since the overhaul?
22 hours since overhaul (it's in a boat)
What type of oil did you use in the break in process?
I used regular 10w30, but with a zinc additive
Were the heads reworked?
Yes, I bought a longblock
Is it using any oil?
Not that I'm aware of
When you performed the compression test it's supposed to be done with the power wire off the distributor,
I disconnected the coil from the dist, but not the power wire
all spark plugs removed
and the throttle set to it's wide open position.
Standing in front of the engine pop the right side valve cover, cycle the engine to Top dead center and see if both valves are closed. If they aren't or if one is partially open then I would say the timing is off on the chain.
In the past I've seen guys replace the timing chain and install it 2 teeth off and the car would still run good. If it's off too much then it won't run at all. Also I wouldn't go by the oem timing spec. SBC's like 12 degrees before top dead center with vacuum advance disconnected and plugged. Once it's set at 12 degrees, reconnect the vacuum advance to a manifold vacuum source, one that pulls vacuum full time including at idle. Then recheck timing, it should be 18 to 24 degrees before top dead center. Do this and it'll pick up considerable more power, use less fuel and will have far better low speed cruise manners.
it's a mechanical advance distributor if I'm not mistaken. (it's in a boat)
What size camshaft did you use?
It's a Sealed power cs1043m. I can't find hardly any info on it. The guy I bought the engine from didn't have much info either
Is the power wire to the distributor going to cause the compression test to be that far off? I'll re check it with that wire removed. I also shot a little oil down cylinders 2468 and got no difference in psi.