C1 Off Road Exhaust

[Jeff C.]

For sometime I have thought that an off road exhaust system was available on C1's. However, a recent search of my corvette books and reference material does not show a option number for this. Was it standard on high HP engines, dealer installed, or only available starting in 1963 as the N-11 option?
Thanks,
Jeff

[Wayne P.]

Re: C1 Off Road Exhaust

My 62 FI has factory installed off road exhaust. It's listed on the factory shipping document that came with the car. Mufflers are round rather than oval.

[Larry C.]

Re: C1 Off Road Exhaust

Jeff,

My '62 (#13078 with 340 hp, 4 spd) which I have owned since April 1965 also came with factory installed off-road mufflers. I have a copy of the original Manufacturer's Statement of Origin as delivered by Chevrolet to the new car dealer listing all options purchased with the car but there is no listing for off-road mufflers. Apparently, the off-road mufflers were available upon request but no additional charge.

At a swap meet about 20 years ago, I was lucky enough to purchase an NOS pair of off-road mufflers which are identical to the ones on my '62.

Larry

[Wayne P.]

Re: C1 Off Road Exhaust

Ok, I went and dug out the 62 Vette stuff. Per my shipping document from GM to Harry Mann Chevy, option 441A is Off road exhaust, $0 cost.

[Stewart A.]

Re: C1 Off Road Exhaust

Ok ive been waiting for this topic to arise. What the hell is of road exhaust mean. I would of thought off road means race exhaust for off road, extractors, larger diameter pipes, lower restriction mufflers and obviously loud. Can you guy's tell me what you get in a Corvette off road exhaust. I have seen it advertised on cars many times for sale and all I can see that is the difference is round hot dog mufflers. Stewy

[Bill M.]

Re: C1 Off Road Exhaust

Ok ive been waiting for this topic to arise. What the hell is of road exhaust mean. I would of thought off road means race exhaust for off road, extractors, larger diameter pipes, lower restriction mufflers and obviously loud. Can you guy's tell me what you get in a Corvette off road exhaust. I have seen it advertised on cars many times for sale and all I can see that is the difference is round hot dog mufflers. Stewy

My guess is that off-road exhaust means that the system does not comply with noise regulations in some area where the car is sold.

It defines function (loud) as opposed to parts.

[Richard T.]

Re: C1 Off Road Exhaust

The C-1 off road exhaust is really a low restriction glass pack muffler with little to no internal baffling. They are quite loud compared to the standard oval mufflers. It's a love hate thing as many guys don't like the noise so stick with the standard oval mufflers. Finding NOS off road mufflers today is rare. Rich

[Duke W.]

Re: C1 Off Road Exhaust

From prior discussions, I think the story goes something like this.

There were two different muffler designs in the C1 era - a straight through glass pack type and an oval reverse flow type. Prior to '62 the type used depended on the engine option with some or all mechancial lifter engines receiving the straight through type. The customer could not specify one or the other. The muffler type was tied to the engine option through 1961.

Beginning in 1962 the the oval reverse flow type became standard equipment for all engines, and the straight through glass pack type became optional for all engines as RPO 441A as stated above, but 441A is not listed in the NCRS Spec Guide for '62 models.

If anyone knows the details I'd like to see which engine got which muffler type from 1957 to 1961.

Duke

[Bill M.]

Re: C1 Off Road Exhaust

If anyone knows the details I'd like to see which engine got which muffler type from 1957 to 1961.

Duke

The '59 283/290 got the round mufflers. I remember them as being a steel pack.

[Donald B.]

Re: C1 Off Road Exhaust

I have the off road on my '62 - the previous owner put them on - I doubt the car came that way.

As for sound - obviously louder than the oval style, but not anything compared to the '69 Z28 with headers and Flowmasters or my (hopefully) soon to be running '65 HIPO Mustang with the repo original exhaust system.

Love / Hate - I like them. Not obnoxious but definitely sounds like there is an engine under the hood - even with the 250 HP.

[Larry C.]

Re: C1 Off Road Exhaust

I may take offer some disagreement with some of the above comments regarding the off-road muffler as being a glass-pack type muffler. Externally, it may look similar to a glass-pack, but I have two sets of NOS off-road mufflers which were probably sold over the counter in late 70s or early 80s.

You can look in the end with the short piece of pipe and clearly seen substantial baffling inside. In fact, the external skin of the mufflers are covered with six circumventual rows of spot welds with each row containing at least four spot welds each. These spot welds serve only one purpose and that is to hold the baffling in place.

Further, I discussed this issue with some members at the Waco Regional today and one member surmised that the off-road mufflers were part of the RPO "engine option" chosen by the buyer. Seems logical that all high performance engines , ie the 340 and 360 hp in 1962, would come with this low-restriction exhaust. Over the past 25 years, I have examined numerous 61 - 62 Vettes and do not ever remember seeing any with original high horse engines that did not have the off-road mufflers. So, the conclusion I have come to is that the off-road exhaust was not listed as an option because it came standard with the high performance RPOs.

[Duke W.]

Re: C1 Off Road Exhaust

I'll take your word on the construction details. To casual observation they appear to be like aftermarket glass packs. Would it be fair to decribe them as "straight through"? "Chambered?"

Do they appear to have any packing?

Given that RPO 441A was a no cost option on Wayne's '62 FI perhaps they were still standard on mechanical lifter engine options in '62.

Has anyone ever seen a reference to 441A prior to '62 - like on any factory documentation on a pre-'62 car?

I think the term "off-road" was Chevrolet's way to warn customers that they were loud and only meant for customers who wanted higher performance at some expense to comfort. They are not illegal for road use, but there were no federal noise standards in that era, but some localities may have had noise standards.

Federal noise standards were implemented sometime in the seventies.

Duke

[William C.]

Re: C1 Off Road Exhaust

Duke, I "Tested" an NOS "off-road" muffler, and there is baffling in the muffler, but directly on center, but there is also a straight line open path from inlet to outlet. Can't see inside because of the angles pipe at the front that is integral, but a test rod went in more than the length of the muffler without an issuer on center, but caught on the baffles just off center.

[Dana B.]

Re: C1 Off Road Exhaust

Do I recall from Noland's C1 book, all Engine 1956 and 1957's have only round / off road mufflers ?

I just changed my 220 HP base engine mufflers from oval to round.
" How sweet it sounds"

Dana

[Larry C.]

Re: C1 Off Road Exhaust

Duke,

There are four baffles evenly spaced down the length of the muffler. Each baffle is like a circular stamped metal disk with two side-by-side holes each about 1.5" diameter. Each baffle is held in place by six spot welds around the outside of the muffler. With a flashlight held just right, you can see to the other end of the muffler but the exhaust would not have a straight pass through. Other than the four baffles, there is nothing else, and no fiberglass packing.

The spot welds on the NOS mufflers are exactly the same as my original factory-installed off-roads, so I would assume that the bafflings were same or pretty much so.