Midyear Off-Road Exhaust

[David S.]

Hi Guys,

Is there a difference between the back sections of 63 Corvette Off-Road Exhaust and 67 off road exhaust? Both are 2-1/2 inch pipes welding to N11 mufflers. Any other differences?

Thanks,
Dave

[Mike M.]

Re: Midyear Off-Road Exhaust

no difference to my knowledge.mike

[Dan H.]

Re: Midyear Off-Road Exhaust

Hopefully you have a later 63 without the depressions beneath the seats. They will interfer with the N11 pipes I'm told.

[Sander B.]

Re: Midyear Off-Road Exhaust

the 63 back section pipes have more bends in them,
so they dont interfere with the early 63 deep depressions underneath the seats


Sander,

[David S.]

Re: Midyear Off-Road Exhaust

Thanks Guys. So to recap, 64 - 67 N11 Off Road exhaust is all the same (the rear sections). But 63 uses a separate system?

Thanks,
Dave

[John H.]

Re: Midyear Off-Road Exhaust

Thanks Guys. So to recap, 64 - 67 N11 Off Road exhaust is all the same (the rear sections). But 63 uses a separate system?

Thanks,
Dave

Dave -

Noland's book and the NCRS Spec Guide both indicate that no units were built with N11 in 1963. Others may have better info.

[Duke W.]

Re: Midyear Off-Road Exhaust

Even though N11 was listed as a '63 option none were installed. The rear pipe section of the off-road system didn't have the necessary jogs to clear the deep seat wells on '63s, and even though late '63s have shallow wells that I think will fit the '64-'67 off road system, St. Louis still never installed any on '63s. It could be that production parts were just too late to make the '63 model year without expediting (which would probably cost more), so N11 wasn't released until the beginning of the '64 model year.

All the GM plant-installed and OTC off-road rear sections include an integral rear pipe section and muffler that will not fit '63s with deep seat wells unless you cut off the muffler and weld it to the correct '63 rear pipe section.

I'm not sure about the new "off road" muffers now offered that are supposed to be internally identical to the original GM design, but if they are separate from the rear pipes they should clamp on to a '63 rear pipe section. If they are integral it would be up to the vendor whether or not he wants to weld an off-road muffler to a properly fitting '63 rear pipe, but GM never did this.

Duke

[Dan H.]

Re: Midyear Off-Road Exhaust

One other problem, the 63 header pipe and 64 thru 67 pipes are reversed as to how they slip into each other. If a 63 owner had a 'late' 63 one without pans he would need the whole set, not just the rear pipe and muffler assembly. I put a complete GM off road system on my 63, sn 13528, fit fine, no wells etc. Rear pipe on 64 thru 67 is a female to help prevent leaks.

[David S.]

Re: Midyear Off-Road Exhaust

Very useful information. Thanks!

[Dick W.]

Re: Midyear Off-Road Exhaust

It is not that hard to modify the pipes to clear the "bait wells" in the early '63's. You just need someone with a muffler shop that will take the time to kick the pipe out to clear the wells, and then kick it back in past that point so it will fit. I have installed three sets of original N-11 pipes on early '63's. Boy, do they sound good on a FI engine Believe it or not, "Mr Augusta Midget" passed one of them on a PV

[Peter L.]

Re: Midyear Off-Road Exhaust

Papa Smuff - Just shows everyone loves the sound. Pete

[Duke W.]

Re: Midyear Off-Road Exhaust

One other problem, the 63 header pipe and 64 thru 67 pipes are reversed as to how they slip into each other. Rear pipe on 64 thru 67 is a female to help prevent leaks.

I forgot about that!

Duke