67 with side pipes louder than 66??

[William B.]

I have a 66 427/390hp. with sidepipes and a 67 427/390hp. with sidepipes. With both cars engines running side by side, the 67 is a lot louder than the 66. From what I have read the 67 must have repo sidepipes and the 66 has origional gm pipes. Is there a way to tell which is the gm pipe or which is the repo pipe? I am thinking of switching the pipes around to make the 67 quieter, because if I drive any distance I always take the 67. Any opinions? or is switching the pipes not the answer?

[Rick S.]

Re: 67 with side pipes louder than 66??

Bill,
On my 67 small block side pipe car I have the GM part numbers stamped into the pipe near the first bend from the manifold. My GM part numbers are 3877215 and 3877216. In addition I found "GM W" stamped nearby and was told by John Hinckley that was most likely for Walker Manufacturing, the supplier of pipes back in the day. The stamping numbers were not very large and I discovered them when the pipes were off the car. Hope this helps.
Rick

[William B.]

Re: 67 with side pipes louder than 66??

Thanks Rick, I will get under the car tomorrow and look for those.