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Enough vacuum?

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Old 03-11-2023, 10:32 AM
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Car: Trans Am GTA 1991
Engine: L98 with Super Ram and Fitech
Transmission: 4L60
Axle/Gears: 3.23:1
Enough vacuum?

Switched to an Accel super ram and feels it's a little bit hesitant to idle. It starts but....i dont know....doesnt feel as on-it's-toes like it did with the old GM tpi-setup. It pulls 17 hg vacuum, just in the green on my tester. Since there's a lot of snow im just in the garage testing stuff out. I have no idea how it feels on the road.

Everything is torqued, rtv'd, re-torqued and triple checked but I'd like to see that vacuum to 18-20.. im testing without hvac vacuum line and egr delete. All unused nipples are plugged.

What's left to do? Smoke test?

Last edited by Andreas_91GTA; 03-11-2023 at 06:27 PM.
Old 03-11-2023, 12:48 PM
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Car: Trans Am GTA 1991
Engine: L98 with Super Ram and Fitech
Transmission: 4L60
Axle/Gears: 3.23:1
Re: Enough vacuum?

Originally Posted by T.L.
What was the vacuum reading with the original manifold?...
Wish I knew. The real difference is cold starting where the original just started really strong and the super ram wants some throttle first 5 seconds to not stall.
Old 03-11-2023, 03:48 PM
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Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Enough vacuum?

Smoke test it for leaks if you think it's an issue. Was this a stock cam engine? It may just need a tune.
Simple smoke machines can be bought relatively inexpensive. Made up for even cheaper or borrowed too. Asking a local shop to do it is sometimes an option.
Old 03-11-2023, 06:27 PM
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Car: Trans Am GTA 1991
Engine: L98 with Super Ram and Fitech
Transmission: 4L60
Axle/Gears: 3.23:1
Re: Enough vacuum?

Originally Posted by aliceempire
Smoke test it for leaks if you think it's an issue. Was this a stock cam engine? It may just need a tune.
Simple smoke machines can be bought relatively inexpensive. Made up for even cheaper or borrowed too. Asking a local shop to do it is sometimes an option.
Yep, stock cam. Can't really think of anything else other than a small leak making it behaving like this. I have resetted the IAC, triple checked every connection and replaced all vacuum hoses.
Kind of prefer a major issue than this (guessing) sneaky leak somewhere
Needle on the vacuum gauge is steady at 17. But, maybe it was at 17 before I tore it down.







Old 03-11-2023, 08:20 PM
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Car: 84 TA orig. 305 LG4 "H" E4ME
Engine: 334 SBC - stroked 305 M4ME Q-Jet
Transmission: upgraded 700R4 3200 stall
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Re: Enough vacuum?


Hose pinch off pliers:
Amazon.com: 3 Pack Hose Pinch Off Pliers, Clamp Set in 3 Sizes for Radiator, Brake, Coolant, and Fuel Lines, Red : Automotive Amazon.com: 3 Pack Hose Pinch Off Pliers, Clamp Set in 3 Sizes for Radiator, Brake, Coolant, and Fuel Lines, Red : Automotive
Pinch off your new vacuum hoses one at a time and watch for any differences in the gauge reading.
Old 03-12-2023, 05:54 AM
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Axle/Gears: 3.23:1
Re: Enough vacuum?

I dont know what im suspecting. Today after 5 min running the idle started to wander all over the place. Could it be something temperature related?
Old 03-12-2023, 10:51 AM
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Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
Re: Enough vacuum?

What donyou mean by wandering? Like a surging? Vacuum leaks can cause that.
Old 03-12-2023, 11:04 AM
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Car: Trans Am GTA 1991
Engine: L98 with Super Ram and Fitech
Transmission: 4L60
Axle/Gears: 3.23:1
Re: Enough vacuum?

Originally Posted by aliceempire
What donyou mean by wandering? Like a surging? Vacuum leaks can cause that.
Yes, surging. When the rpms dropped so did the vacuum. I guess it's the IAC letting air in keeping it running? It was going (guessing) between 500 and 1000 rpm a couple of times. This is when it was up to operating temp. On its way to operating temp it was stable.

I should mention my problem isn't super high idle. Problem is it does not wanna start as strong as before the intake change.and that's what's bugging me.

And I haven't driven it yet. Maybe other stuff will happen when the engine is under load.
Old 03-18-2023, 06:53 AM
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Car: Trans Am GTA 1991
Engine: L98 with Super Ram and Fitech
Transmission: 4L60
Axle/Gears: 3.23:1
Re: Enough vacuum?

Bought a smoke machine and found a loose bolt holding the throttle wire bracket. Should've checked it and saved money but oh well...."learning investment". Now it's pulling 19-20 hg and starts right up.
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