I was hoping someone could help with this sound. With no load on the motor, it sounds good, smooth. When accelerating, the exhaust sounds good, but the engine sounds like it's either missing on a cylinder or maybe the valves. The noise is kind of a chug sound and gets faster with acceleration. It is a 455, with an HEI. About three weeks ago I changed the plugs, cap, and wires. She likes to drink the gas, but she's fast, I am fairly new to diagnosing engine and tuning issues, anyone with advise on what I should check would be appreciated,
Thanks

 

Pretty hard diagnosing a noise on the internet.
Does the car feel like it has a miss?

 

Is it hard starting??

Did the symptoms occur after you gave it a tune up?

I guess you could double check your plugs and wires. Ensure the plugs are gapped correctly and the plug wires are routed correctly.

Fuel filter been changed? Carburetor been cleaned or needing rebuild kit?

Without hearing it or knowing all the details it will be hard to diagnose, but those are a few things to double check.

d1

 

I have had bad plug wires right out of the box that cross fire under load such as accelerating. Look for burn marks on the plug wires where they cross over each other at the distributor.

 

If it idles good and clears up when the throtles are close to wide open it could be a clogged intermediate speed circuit in the carb. It will feel like a miss and make somewhat rythmic chug noises. Make certain the plug wires are made for HEI.