popping back through the carb. - Team Camaro Tech
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post #1 of 8 (permalink) Old Feb 6th, 06, 05:41 AM Thread Starter
 
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popping back through the carb.

before i talk to my engine builder i am looking for some expert advice about this problem. first, 69 302 z28. complete rebuild on engine and carb. 4130. lt1 cam and lifters. hydraulic. problem lies in the initial take off. it seems to drag or to have a dead spot until you get past aroung 1500 rpm then it runs like a bear. sometimes when you take off it will pop back through the carb. on occasion when i hit the gas befoer downshifting it too will backfire throgh the carb. the distributor is not the "302" original but a small block from i believe agout 1972. i don't have the specs on the timing in front of me at the moment but can get them.the builder says that they cannot do anything more with the carb to solve the problem. i just don't know that the carb is the problem. maybe it's the distributor. they told me they put a 650 on the car to see if they could get it to idle better and they said that cured it. i just don't know if they test drove it with that carb. i'll call. i hope someone can set me straight with this. thank you for your time.
barry
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post #2 of 8 (permalink) Old Feb 6th, 06, 12:45 PM
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Re: popping back through the carb.

Adjust your carburetor, it sounds like it might be running to lean. Also check for any vacuum leaks that might be making the carburetor run lean, such as a leaking base gasket. Then make sure the timing is set correctly. It might be running on the retarded side, since you are lacking power.

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post #3 of 8 (permalink) Old Feb 6th, 06, 03:37 PM
wdf
 
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Re: popping back through the carb.

Quote:
Originally Posted by biil9
before i talk to my engine builder i am looking for some expert advice about this problem. first, 69 302 z28. complete rebuild on engine and carb. 4130. lt1 cam and lifters. hydraulic. problem lies in the initial take off. it seems to drag or to have a dead spot until you get past aroung 1500 rpm then it runs like a bear. sometimes when you take off it will pop back through the carb. on occasion when i hit the gas befoer downshifting it too will backfire throgh the carb. the distributor is not the "302" original but a small block from i believe agout 1972. i don't have the specs on the timing in front of me at the moment but can get them.the builder says that they cannot do anything more with the carb to solve the problem. i just don't know that the carb is the problem. maybe it's the distributor. they told me they put a 650 on the car to see if they could get it to idle better and they said that cured it. i just don't know if they test drove it with that carb. i'll call. i hope someone can set me straight with this. thank you for your time.
barry
"backfire" in the intake occures when the intake valve opens (or fails to close)
with a spark / flame front / or HOT spot- in the cylinder. the majority of these
events are caused by spark/timing issues NOT fuel! Carefull examination of the secondary ign system and timing controls WILL fix all but the ocasional mechanical problem!
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post #4 of 8 (permalink) Old Feb 7th, 06, 06:24 AM Thread Starter
 
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Re: popping back through the carb.

thank you
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post #5 of 8 (permalink) Old Feb 7th, 06, 06:24 AM Thread Starter
 
Join Date: Oct 2004
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Re: popping back through the carb.

thank you. i will pass that info on to the engine builder.
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post #6 of 8 (permalink) Old Feb 10th, 06, 02:14 PM
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John
 
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Re: popping back through the carb.

Quote:
Originally Posted by biil9
lt1 cam and lifters. hydraulic.
The LT-1 cam isn't hydraulic - it's solid lifters.

JohnZ
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post #7 of 8 (permalink) Old Feb 10th, 06, 04:21 PM
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Re: popping back through the carb.

Quote:
Originally Posted by JohnZ
The LT-1 cam isn't hydraulic - it's solid lifters.
Really? I thought the LT-1 used hydraulic rollers.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #8 of 8 (permalink) Old Feb 10th, 06, 07:13 PM
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Wes
 
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Re: popping back through the carb.

Agree wdf above,..adjust the timing.
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