Intake manifold vacuum
06-22-2018, 04:45 PM
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Car: 1992 Z28 1LE
Engine: L98
Transmission: 700R4
Axle/Gears: SLP dana 44 3.92
Intake manifold vacuum
Roughly what kind of intake vacuum are you guys seeing with a decent size cam and heads? I am chasing an issue and wondering on vacuum. I checked my stock L98 and it's about 22in of vacuum and this 87 I'm working on has a 224/230 cam, big heads, about 10.5:1 and a big intake on it and it's around 12-13in of vacuum at idle. Is that about right for the size of cam and intake?
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Patu (04-25-2020)
06-22-2018, 08:09 PM
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Re: Intake manifold vacuum
Roughly what kind of intake vacuum are you guys seeing with a decent size cam and heads? I am chasing an issue and wondering on vacuum. I checked my stock L98 and it's about 22in of vacuum and this 87 I'm working on has a 224/230 cam, big heads, about 10.5:1 and a big intake on it and it's around 12-13in of vacuum at idle. Is that about right for the size of cam and intake?
06-22-2018, 11:10 PM
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Car: 1992 Z28 1LE
Engine: L98
Transmission: 700R4
Axle/Gears: SLP dana 44 3.92
Re: Intake manifold vacuum
That was high idle for the stock L98, didn't think about RPM variance, I would assume it drops a little once it's warm. I will warm it up tomorrow and check, but if 13ish doesn't seem alarming then I might be ok on vacuum leaks
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