BACKFIRE
Thread Starter
Instructor
Joined: Jul 2001
Posts: 157
Likes: 0
From: OLATHE, KS
BACKFIRE
Hopped in the vette today and now have a "small" backfire out of the passenger side exhaust. Fairly new to the vette world and was hoping for a little help on where to get started. It's a 62 327 fullie. If it matters, there was a pertronix installed a couple of months ago but no previous problems, new AC45 plugs and wires earlier in the spring. Any input would be appreciated. Could'nt really find any troubleshooting help in the ST-12 or Chiltons.
[Modified by CHRISP, 2:29 PM 11/15/2001]
[Modified by CHRISP, 2:29 PM 11/15/2001]
Le Mans Master
Joined: Dec 2000
Posts: 7,245
Likes: 4
Re: BACKFIRE (CHRISP)
I'd start here:
- check intake manifold gasket for leaks
- spark plugs - look for wear, wetness, cracks, improper gap, burned electrodes, and heavy deposits.
- ignition coil connections
- ignition system for moisture, dust, cracks, burns, etc. Spray plug wires with fine water mist to check for shorts.
- ignition system for faulty grounds
Someone else will have others.
- check intake manifold gasket for leaks
- spark plugs - look for wear, wetness, cracks, improper gap, burned electrodes, and heavy deposits.
- ignition coil connections
- ignition system for moisture, dust, cracks, burns, etc. Spray plug wires with fine water mist to check for shorts.
- ignition system for faulty grounds
Someone else will have others.
Racer
Joined: Sep 2001
Posts: 371
Likes: 1
From: Nashville TN
Re: BACKFIRE (67HEAVEN)
An aerosol can of starting fluid(ether) is good for finding intake/vacuum leaks. Just spray it in the suspected area and the engine will speed up if there is a leak; like at the base of the carb. Be careful; too much can blow a head gasket.
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: BACKFIRE (CHRISP)
Exhaust backfires are usually a result of unburnt fuel being ignited after leaving the combustion chamber (either by a subsequent firing of the same cylinder or by the still burning gasses of an adjacent cylinder). In some cases one cylinder is getting more fuel than it's plug can fire but more often it's the result of an ignitiion miss that doesn't fire the plug. Any of those things already suggested could cause this. Usually, a plug reading will identify the offending cylinder (the one that's not firing will be darker). Another possibility is a problem in the exhaust sytem. A leak at or near the manifold will let air in to ignite unburned fuel and also let you hear the result.
