I checked it last night and I was getting about 22, which was above the "normal" range on the gauge I had. The needle fluctuated ever so slightly, at the most by .1. In drive the vacuum went down just a little bit, it was about 21 or so.

Thanks,
Brandon

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White '92 Firebird w/ 305 TBI. Open element w/ non drop base, increased fuel pressure, TBI spacer, Hedman Hedders & y-pipe, no cat, cat-back exhaust

 

Tab, what are the specs on your cam? Mine is a relatively mild comp cam with 242* duration and 108* LSA. I pull about 18-19" at idle in drive. I was wondering if this was a little bit low myself in that my idle will vary a little with the AC on in drive. Other than that it does pretty good considering the 108* LSA.

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!

 

That vacuum reading is normal for a stock engine.

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George P. Lara
1994 Z28 LT1 T56
1984 Z28 High Output
Member: SCCA, SCFB, SC3GFB

 

DAMN that's a low LSA! I thought I was pretty low with a 110 cam in my TPI! LOL

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92 Z28 L98 350
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Ported and polished heads, ported stock TPI base, ported plenum, Comp Cams XR270HR-10 cam (lift .495/.502 duration 218/224 lobe separation 110), Edelbrock TES headers, LT4 valve springs, Crane AFPR, Flowmaster catback with LT1 style tips, MSD coil & wires...

"Take that auto, drop it in first, hold the brakes, stomp the gas and grin from ear to ear! :-)

 

Low Lobe seperation but much less overlap because of low duration... = good torque

 

most excellent torque actually with just a hick-up in the idle from time to time. The cam was a mistake due to a total lack of knowledge of computer controled engines at the time.....................oh well still a total lack of knowl............

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"84Z28/'91 305TPI comp cam flowmaster TB coolant bypass/shutoff valve to heater core MAT relocated Ram-Air(home-made) gutted air-box IROC ground effects/wheels GY245/50's 700R4 superior shift kit/ corvette servo(excellent shift kit BTW) Rebuilt engine and transplanted it myself. Love this engine!
LOW performance people should drive low performance vehicles!