1968 Chevy Camaro Backfiring when cold

Tiny
CAMARO1968
  • MEMBER
  • 1968 CHEVROLET CAMARO
  • V8
  • 2WD
  • AUTOMATIC
  • 93,000 MILES
Hello,
Although the car is old, the engine is a brand new Jasper 350 with an Edelbrock 600 cfm carb and a new Mallory ignition. The 93,000 miles isn't significant because the car is fully restored.
When the car is cold, it backfires at the carb. When the car warms up to about 170 degrees, the backfiring stops but the engine hesitates a bit and doesn't perform well.
I have tried everything with the choke and mixture screws but I cannot get this thing to stop coled backfiring.
Besides the carb, what else can cause this. I have checked for vacuum leaks and find none.
Thanks!
Joe
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Saturday, December 1st, 2007 AT 5:11 PM

5 Replies

Tiny
PEAR69
  • MEMBER
Check and see if the distributer is installed properly. Is there a spark advance or retard in the system?
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Saturday, December 1st, 2007 AT 10:50 PM
Tiny
CAMARO1968
  • MEMBER
I wouldn't know if it is installed properly. My mechanic just put it in a few weeks ago and things were fine.
I am not too mechanically inclined so I don't know about spark advance or retard either, sorry.?
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Sunday, December 2nd, 2007 AT 2:16 AM
Tiny
PEAR69
  • MEMBER
If you are not mechanically inclined, then do not mess around with the carb. Mixing screws or the choke. I assumed you knew what you were doing when you said you tried everything with the carb. And choke. Jasper motors are some of the best in the business. When they are fed by an Edlebrock carb. And intake, they can produce lots of power.
When an engine back fires you run the risk of hurting yourself or bending a valve. I'm afraid that when you say the engine does not peform good when it's warm, this means you are running it in this condition. The valve is probably already bent because the engine was ran too long in a backfiring condition. This is probably why it doesn't perform well. I would do a compression test and a leak down test just to be sure. Take this awsome car back to the mechanic, tell him or her what adjustments you made to the carb, and what it's doing. Also have the mechanic do a leak down and compression test. I hope you didn't bend a valve because this requires the heads to be removed and a new valve job. Good luck
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Sunday, December 2nd, 2007 AT 8:37 AM
Tiny
CAMARO1968
  • MEMBER
Thanks very much for the reply.
I have only driven the car up and down the road a bit each morning to check if the choke adjustment helped, but it hasn't.
I will call the fellow who installed the motor. It is under a 100,000 mile warranty so it won't cosy anything.
Thanks for all your time!
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Sunday, December 2nd, 2007 AT 8:41 AM
Tiny
PEAR69
  • MEMBER
Thanks very much for the reply.I have only driven the car up and down the road a bit each morning to check if the choke adjustment helped, but it hasn't.I will call the fellow who installed the motor. It is under a 100,000 mile warranty so it won't cosy anything. Thanks for all your time![/Quote:06ff9b11a3] Ok, and please take care of that car! Do not drive it until this problem is fixed, you'll only make it worse.
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Sunday, December 2nd, 2007 AT 8:50 AM

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