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Old 05-09-2021, 06:17 PM
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67gtospud 67gtospud is offline
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Join Date: Aug 2012
Location: Seymour, Wisconsin
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Quote:
Originally Posted by tom s View Post
Have you tried it with VA hooked up?Tom
I disconnected it until I get my tuning sorted out.



Quote:
Originally Posted by steve25 View Post
I don’t understand why your idle vacuum is so low!

If you do a hot cranking compression test what results do you get?

It’s good though that you experimented and found out that you can not run a progressive linkage set up on a manifold like that with it’s nature to act more like it has two separate Plenums even though it’s pretty open on the inside!
I'd imagine the long duration cam and large amount of valve lift would be the cause of the low vacuum. I haven't done a compression test. Engine is a fairly fresh build with about 2k miles on it.
With progressive linkage driveability was fine but throttle response is day and night after switching to straight linkage.

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1967 GTO, 432 (428+.030), 4-bolt mains, factory Nodular crank, scat rods, icon dished pistons, Lunati HR 243/251@.050, .618/.622 lift, Edelbrock 72cc round port heads, 10.5:1, offy 2-4 intake, Edelbrock 650cfm carbs, Super T10 trans (2.64 first), BOP 10 bolt w/ Eaton posi and 3.36 gears