Folks,
A colleague and I have recently rebuilt my engine and having had a bit of an issue when cold which goes away when the engine heats up, I thought having replaced just about everything we would take some vacuum readings.
The engine has 4V closed chamber heads that have been fully refurbished/rebuilt (I wanted to go standard rather than alloy heads). The camshaft is a Comp Cams 292H (part No. 32-234-4; grind number FC 292H-10) and has the matching comp cam springs. It also has Crane 316T roller rockers fitted.
The manifold is a Ford racing dual plane set up and I have a new Holley 600 with vacuum secondaries.
With the PCV blanked off and also the distributor advance, I get about 10 psi vacuum at the manifold steady at idle (800 RPM), this increases to about 14 when throttle is blipped. At the base of the carb the vacuum is about 9-10 but fluctuates.
I have tried to get some data from Comp Cams but no reply to my note, so now wonder if this is due to overlap or actually a vacuum leak. The rough idle goes away when warmed up, but the vacuum reading does not change.
Any views?
Regards
Adrian
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