Rochester Q-Jet .....
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Junior Member
Joined: Apr 2001
Posts: 4
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Rochester Q-Jet .....
ok, i put a cam in my car and finally got it to start up. It runs but it wont idle, i have to keep on the gas to keep it alive. I'm not sure if all the vacuum stuff is hooked up correctly but for the most part it's all closed off. What is the problem??
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
As for the carb, hook up ALL of the the lines, etc. EXACTLY like they were berfore you ripped into the motor (I assume it ran fine before). There's a little sticker on the radiator support that shows you the correct routing of all the vacuum lines. Now, we're covering a BROAD subject here and that's a fairly general answer.
There are other possibilites:
1. Incorrect valve adjsutment. If they're loose you'll get loud ticking from the rocker arms (of course) but it will generally idle OK. HOEWEVER, if you get the adjustment nut tightened TOO FAR DOWN you will run the hydraulic lifter out of adjsutment range and the valve will hang open slightly, not allowing the cylinder to seal very well. The idle will get like a top-fuel car. Real rough idle, maybe no idle at all.
2. Ignition timing is off. Real easy to get the timing screwed up. My favorite way to mess it up is to install the cam, line up the marks on the timing chain but then drop the dirstributor back in whichever way it was pointed when i too the motor apart. Oops. But even if you get everything lined up OK you could still have the timing retarded far engough to kill the idle.
Good luck
There are other possibilites:
1. Incorrect valve adjsutment. If they're loose you'll get loud ticking from the rocker arms (of course) but it will generally idle OK. HOEWEVER, if you get the adjustment nut tightened TOO FAR DOWN you will run the hydraulic lifter out of adjsutment range and the valve will hang open slightly, not allowing the cylinder to seal very well. The idle will get like a top-fuel car. Real rough idle, maybe no idle at all.
2. Ignition timing is off. Real easy to get the timing screwed up. My favorite way to mess it up is to install the cam, line up the marks on the timing chain but then drop the dirstributor back in whichever way it was pointed when i too the motor apart. Oops. But even if you get everything lined up OK you could still have the timing retarded far engough to kill the idle.
Good luck
Joined: Mar 2000
Posts: 43,187
Likes: 45
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
To that I would add making sure you have the spark plug wires going to the proper cylinder, especially if you took the wires off the cap.
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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" Hedders, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere w/open diff & slipping tranny. Daily driver while Camaro was being put together.
------------------
82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" Hedders, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere w/open diff & slipping tranny. Daily driver while Camaro was being put together.
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