vacum at idle
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Junior Member
Joined: Jun 2002
Posts: 88
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From: Michigan
Car: 88 gmc 1500
Engine: 496
vacum at idle
whats up
just got my engine running a few weeks ago and it runs pretty good it deos run rich most of the time though. i have a 355 with a xe 268 cam and vortech heads with the z28 springs, an rpm airgap manifold and a 670 holley street avenger its got 9:1 compreesion. I was just wondering what you think the vacum should be at idle right now its about 12-13 is this good or bad as for it running rich should i jet it down or turn the pressure on the regulator down its set at 7 psi and the level in the bowls is correct.
thanks
just got my engine running a few weeks ago and it runs pretty good it deos run rich most of the time though. i have a 355 with a xe 268 cam and vortech heads with the z28 springs, an rpm airgap manifold and a 670 holley street avenger its got 9:1 compreesion. I was just wondering what you think the vacum should be at idle right now its about 12-13 is this good or bad as for it running rich should i jet it down or turn the pressure on the regulator down its set at 7 psi and the level in the bowls is correct.
thanks
Supreme Member
Joined: Jul 1999
Posts: 18,457
Likes: 16
From: Loveland, OH, US
Car: 4
Engine: 6
Transmission: 5
That's a little low, i would expect to see about 15-16.
7 psi is more than you need; 5 is usually plenty, and with a good-flowing system, 3 will do.
with that low vacuum th epower valve is probably opening alot of the time at idle. that will make it run shamefully rich.
7 psi is more than you need; 5 is usually plenty, and with a good-flowing system, 3 will do.
with that low vacuum th epower valve is probably opening alot of the time at idle. that will make it run shamefully rich.
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