67 427 sidepipe help and advice

[Robert D.]

i have 2 sets of sidepipes.
the grayish set is off of my car if you notice the part number is stamped on the pipe, the flange is different where the donut fits, and the head pipe is round as though it was mandrel bent. it appears that color because it was rusted, pitted and i sandblasted them.

the second set is an nos pipe with the gm sticker and part number on it. the part number on both pipes is the same the second pipe has bends in the pipe and the head pipe flange is only a flare.

my questions are
1 why are they different is the second one a later replacement.
2. will they both pass judging
3. which one would you use
4. will one seal better than the other

thanx
bob

[Stephen L.]

Re: 67 427 sidepipe help and advice

I believe the short straight section is an insert and the new pipe doesn't have it installed.....used on BB cars.

[Robert K.]

Re: 67 427 sidepipe help and advice

Steve,
What do you mean by an insert? Was this installed by the vendor on the pipes of all side pipe BB cars?

[Robert D.]

Re: 67 427 sidepipe help and advice

Steve your right it is an insert didnt realize that DUH lol what about the flat spot in the new pipe and the fact that the old pipe is totally round can some one comment on that.

[Stephen L.]

Re: 67 427 sidepipe help and advice

Robert, check your AIM under sidepipes. The insert is shown there, which means it was installed during vehicle assy. The flat spot looks like it was done for additional frame clearance, probably needed during hard acceleration when the engine torques....

[Robert D.]

Re: 67 427 sidepipe help and advice

Thanx Steve
do you think it was modified later by the factory no sign of it on the original pipes
bob

[Stephen L.]

Re: 67 427 sidepipe help and advice

I looked at my factory replacement pipes which I purchased about 1982 from another Corvette enthusiast. So I don't know the actual production timeframe, but they do NOT have the flat spot that yours has. Mine had the original GM label and part number.

[Robert D.]

Re: 67 427 sidepipe help and advice

thanx steve maybe someone will chime in and clear this up