carburetor popping??!! - Team Camaro Tech
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post #1 of 7 (permalink) Old Apr 21st, 01, 07:35 PM Thread Starter
Join Date: Oct 2000
Location: Kenosha, WI USA
Posts: 15

Hi this problem thought maybe yous could help me. I've got a 67 Camaro RS with a 327. It has an Edelbrock Performer 4 barrel (part number 1406, you know 600 cfm and electric choke)and intake manifold. My problem is that when the car is not warmed up (and sometimes when it is) the carb pops. Most of the time its when im starting off in first gear. It goes a little then POW and then it's fine. Sometimes it does this in other gears at lower RPMs. It's really bugging me many 67's do you see driving around with this nasty popping sound out of the engine bay. Any help would be greatly appreciated. thanks
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post #2 of 7 (permalink) Old Apr 21st, 01, 08:37 PM
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Location: seattle, wa
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How about the carb gasket?
Throw a towl over the carb does it die?
Are you back firing through the carb?
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post #3 of 7 (permalink) Old Apr 21st, 01, 11:12 PM
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Is it popping back at light throttle or heavy throttle? Either way, check for vaccuum leaks and proper adjustment of the idle mixture screws. Also check the timing. Timing that is too far retarded will cause popping back thru the carb. Also, a very lean primary jetting will cause this...but unless you have a vaccuum leak the jetting should be ok. If, after determining that the idle screws are set correctly and the timing is correct, and that there are no vaccuum leaks, you might try going 4% richer on the primary rods (by the tuning book that came with your carb) and see if this helps. I had to do the same to the 1405 on my truck.

There are a couple of other things that I can think of off the top of my head that will cause popping back thru the carb...incorrectly set valves (too tight or maybe an exhaust rocker too loose), sloppy timing chain (how many miles on that timing set?), and probably the most common reason of carb backfiring, a flat or going flat exhaust lobe on the cam. If the lobe isnt completely flat yet, usually you will only get a backfire at heavy throttle openings. If none of the tuning stuff works out, jerk the valve covers, fire the engine, and see if all of the rocker arms are moving about the same.

Hope this helps.

375hp 78 Chevy truck
77 Chevy Nova
95 Chevy Lumina 3.4L
and building a 78 Nova
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post #4 of 7 (permalink) Old Apr 22nd, 01, 02:19 AM
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Join Date: Nov 2000
Location: Indiana
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A buddy and I just installed a Performer and Holly 4 barrel.

We had the same problem. We advanced the timing! Takes the gas beautifully now at low r's (and high).

I too experienced most of the problems taking off in first gear. Also sometimes happened in 2nd.

Listen to Travis. If you just put the carb on I'd guess the timing.

Good luck!

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post #5 of 7 (permalink) Old Apr 22nd, 01, 07:15 AM
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Sounds like the accelerator pump could use some changes. If advancing the timeing cures it, good but you should shorten up the amount of advance in the dist or you might get into trouble at WOT high RPM

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post #6 of 7 (permalink) Old Apr 23rd, 01, 03:56 AM
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Location: colts neck, NJ
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I have a 327 with a Holley 600. Had the same problem. Cured it by advancing the timing. Now it takes full throttle without popping or stumbling.
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post #7 of 7 (permalink) Old Apr 25th, 01, 04:48 PM
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I had the same problem when I first bught my 69 RS I just reset the screws and that fixed it. Turn them all the way back and then turn them 2 and 1/4 turns out and that should do it. You may need to adjust alittle from there but that should be it.
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