I put a vacuume guage on my 401 and it reads late valve timming and is about 8hg lower than normal. the cam is a mild performance cam from DELTA CAMS in Tacoma. how do you fix late valve timming? do I drill the cam gear and use an offset bushing? it idels OK and revs up like normal. a friend says to bend the needle so it reads normal, but thats not the answer i'm looking for.
Try advancing the ignition timing and see what that happens. Also check with another vacuum gauge. If the motor runs good I don't think you have a cam problem.
Nice avatar, been running mine like it for 25+ yrs had it for over 40. old school is rite, my motto "if it aint broke don't fix it" good luck
A loose or sloppy timing chain would be a first and simple check. Even if it is a new set, if the block has been align bored or align honed, this will or can add to the play in the chain and gears. For some engines, timing chain manufactureres offer undersize chain sets just for this instance. The last and most technical procedure would be to check the cam timing as in " degree the cam ". You will need the cam card for this as well as the appropriate tools common to degreeing a camshaft. 8hg lower than normal or stock might not be a real issue, give us the cam specs and we should be able to quide you better. Include all the info on the cam card for this, TR.
The gauge markings are a generalization for stock equipped engines. A hotter grind cam will decrease the reading. If it runs good, don't worry about the vacuum reading.