It seems that I have a wierd banging noise coming out of the exhaust. It happens randomly every 5 seconds or so, only below 900 rpms or so. This is the first time the motor has been run since the 20 minutes at 1800-2000 rpms for cam break in. The engine is full of fluids that look good, not overheating, timed perfect and oil pressure at 65 psi just off idle. The motor has excellent throttle response, runs well and the noise goes away above 900 rpms or so. The lifters are hydraulic flat tappet, and the valve train came in a kit (XE274), and we set and check for clearance/lash on the stand by an experianced person (and degreed). No clearance issues anywhere on the stand. Any ideas???? I'm going to check rocker arms to valve cover clearance, but I am getting nervous!!! please help....

What are you running for exhaust? manifolds? headers?

Sorry, long tube headers, to 2.5" with dual flowmasters exiting out the rear...

We just fired up my 383 for the first time monday night and after 10 minutes of running I had a similar banging or thumping going on. We are pretty sure it ended up being the torque convertor. He checked the fluid and it circulated throught the lines and then it wasnt registering on the dipstick. So we filled it the rest of the way up and started it again and it sounds much better. It may be this, I am not sure. Just my experience.

Thanks, Erik

To start just idle the car and walk around it. If its coming from the exhaust you should be able to find where pretty easy.

If you can't find it with the car on the ground you can always put it up on jackstands (solidly of course) and slide under the car while its running.

It could be the converter, as the trans and converter is new. I think I have 5 or 6 quarts of fluid in and my shifter is complete so now I can circulate and keep on filling. This goes with Erics thoughts of walking around/getting under the car to check. I doesn't sound like an exhaust rattle/leak, but more like a engine bang thats resonated via the exhaust. Thanks everyone, I'll keep ya posted...

Well I found it and I feel pretty foolish. I had the 6 and 8 plug wire reversed, and that was the noise. I guess I am amazed how well it ran like that, with good throttle repsone and all...Oh well it's fixed- Thanks again everyone!!

Hey at least you found the problem. Thank goodness it was a simple find.
Joe

Thanks for the follow up -- lots of people would have never admitted a mistake or even followed up :thumbsup: you da man

If this is the worst problem I encounter I'll be doing good!! I'm glad it was so easy... Thanks again