Hi, I've just finished installing a new cam, intake, carb (standard Q-jet) and standard HEI on my 83 TA LG4 5spd (all computer stuff is gone). I cranked it up in the garage the other night and it seemed to run fine but I only let it idle for a few minutes as I didn't want to fill the garage up with fumes and give the wife a headache! So, I pulled her out Sunday and had a little trouble getting it started, I messed with the timing a bit and finally got it to crank but it would only run for 5-10 seconds then BAM! I'd get a backfire from the carb, once it even singed the hood insulation. I'm pretty new to this so I don't have a clue other than attempt to reset the timing, adjust the valves (again) and try over. Can anybody offer a wannabe hot rodder some advice?

Thanks...

 

Ummmm nobody even wants to take a stab at this one?

 

Have you made any adjustments to the carb itself?

I rebuilt a carb on my 85 z28 once and didn't have any of the tools needed to make all the necessary adjustments. I do believe that was one of the more ignorant things I've done.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

When you removed the computer, did you swap to a Vacuum-advance style HEI distributor? the LG4 distributor has to have a computer to work properly. Also, you need a non-computer controlled Quadrajet carb. IF you run the computer carb without the computer, it will run rich and idle awful.

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1983 Pontiac Firebird SE
LG4-Based Chevy 400
700R4 Tansmission
Modified 4 Barrel Q-Jet Carb
Accel Super Stock 8mm Wires
Edelbrock Pro-Flo Air Cleaner
3.23 Posi Rear
14X7" Cragar SS/T Wheels
Clarion 45X4 CD/AM/FM Head Unit
100WX2 Amp
2 Pioneer 12" Subs in Custom Box
Third Gen Performance
"A four cylinder is only half an engine"

 

Thanks guys, I did replace the computer HEI with a standard type (Accel blueprint series) and the carb with a non-computer Edelbrock Performer Q-jet. Carb adjustments are a possibility I suppose.

 

Your timing is too far advanced. Move the distrib clockwise (If I remember correctly). Carbs are rarely a source of backfire and when they are it's usually from extreme lean condition causing an enviroment that can combust gas within the manifold.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 Trans Am T-tops
4-bolt main 350, performer intake, headers, Holley 650, T-5, hayes clutch, dual elec. fans and 3.23's.
Daily driver and restoration
13.98 @ 101

[This message has been edited by 84FTA (edited February 16, 2001).]