Off Road Mufflers 1961 270hp

[studiog]

Does anyone know the correct diameter of the round off road mufflers on a 1961 270hp? I purchased an exhaust system and I think the mufflers are too "skinny" only about a 3" diameter. Thanks for any replies.

 

[Ken's67]

I bought my off road exhaust from Corvette Central a few years back. (for my '61) I sold the car since then. If I remember correctly, they where larger then 3", more like 6"-7".
I would call Corvette Central or Zip Products tech support hot line to ask them. They should go back into they shock dept. and measure them for you.
(Where did you get your from?)
Ken:crazy

 

[Viking427]

No such animal... RPO N11 (round "off-road" mufflers) weren't an OPTION on C1's until 1962. They were about 30" long x 5" dia, no internal baffles, only perforations. The mufflers/tailpipes were welded as an assembly. The right side muffler had stainless endcaps to tolerate corrosion caused by accelerated condensation due to cooler temps caused by the heat riser valve.
No suitable reproductions out there that I'm aware of.
You need the ovals to be "correct".
www.mofoco.com/mufflers/mufflers.htm

CORRECTION: Checked notes; Original N11 muffs had three internal baffles...not perforations.

Does anyone know the correct diameter of the round off road mufflers on a 1961 270hp?

 

[JohnZ]

The C1 (1962 - RPO 441) "off-road" mufflers were straight-through, with perforations (like "glasspacks"); the later C2 RPO N-11 "off-road" muffler option was the same oval shape as the standard 5-baffle muffler, but had two less baffles.

Externally, the 1962 RPO 441 "off-road" round mufflers were identical to the round mufflers that were standard equipment (and the only mufflers offered) on all '56 and '57 Corvettes; they went to oval mufflers from '58-'62, with no option until 1962.

 

[studiog]

Thanks everyone for all the info. Very helpful!
Gary

 

[JohnZ]

Re: Black Book error?

John, my First Printing, Black Book, pg. 25, lists RPO 441 with the '61. Has this since been corrected? To your knowledge, have any late production '61's been found with the 441's?

TIA
Dann

The current (2003) edition of the "Black Book" has been updated to reflect what NCRS has been able to document (and what Noland shows in his Vol. II book) - RPO 441 was only available on 62's.

 

[vettefinderjim]

Allen Exhaust??

I believe Allen Exhaust www.allencorvetteexhaustsystems.com services these mufflers also.

And I do remember putting this exhaust system on all my solid axel cars in the 60's and early 70's. For years, we thought the muffler came on all fuel injected and solid lifter cars.