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Low compression after cam swap?

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Old 08-05-2013, 10:24 PM
bassdude bassdude is offline
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Low compression after cam swap?

Took the old 460 out of my Scout rock crawler to freshen it up before installing it in my 77 Scab. Replaced the crank and bearings, put in a Lunati Voodoo cam at the same time.
Decided to check compression by hand with a ratchet on the crank. Only getting 30# on all cylinders. I've got a Cloyes roller chain in the straight up position.
Should I get it to where I can crank it with the starter before worrying about it? Try the Timing chain on the advanced mark?
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Old 08-06-2013, 02:52 PM
85e150six4mtod 85e150six4mtod is online now
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New cam, what about:

--lifters
--pushrods
--rockers
--springs

If something is not compatible with the increased lift of the cam, or if the base circle of the cam is different, low cylinder pressure might result.

Cam timing would also be a suspect, but seems unlikely.

You are not exactly "spinning" the motor with that ratchet, so a lot of pressure will bleed off before you hit TDC, more so with a longer duration cam.

If you don't see anything "funny" with the rest of the valve train, try it with the starter before you make a final decision.
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Old 08-06-2013, 05:35 PM
bassdude bassdude is offline
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yeah, everythings new. I think I will get it sitting in the truck then try it with the starter.
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