1964 exhaust question

[Jeffrey B.]

Did all 1964 Corvettes with the standard transmission have 2.5 inch exhaust manifolds and pipes? Was this considered to be what was referred to as "Off Road Exhaust" in 1964?

Thanks in advance for replys

Jeff

[Alan D.]

Re: 1964 exhaust question

Jeff, I believe that only the HP motors had 2 1/2" exhaust systems.
The Off Road, N11, was an optional straight through pipe with baffling in the muffler.

[Tom H.]

Re: 1964 exhaust question

Hi Jeff !

I don't believe the 2 1/2" system makes it off road, specifically. 300 HP cars with 4 speeds used the 2 1/2" system as well as all of the L76 and L84 equipped units.

That would rule out the system being used totally as off road since only 1953 cars were built with off road exhaust.

[Jeffrey B.]

Re: 1964 exhaust question

Guys,

Appreciate the response.

Jeff

[Bob R.]

Re: 1964 exhaust question

I know in 63 the 250 HP engines had 2" exhaust I assume the 64's did also.

[Alan D.]

Re: 1964 exhaust question

Jeff,
Check out the JG pages 105 & 142. Although page 142 would lead one to believe all 300hp had the 2 1/2, page 105 adds a little clarification when Auto and AC are involved.

[Dan H.]

Re: 1964 exhaust question

Jeff,
Check out the JG pages 105 & 142. Although page 142 would lead one to believe all 300hp had the 2 1/2, page 105 adds a little clarification when Auto and AC are involved.

Hi Alan, had a 64 300hp auto, was 2" system, I guess for clearnce of tranny.
Dan

[Michael H.]

Re: 1964 exhaust question

Did all 1964 Corvettes with the standard transmission have 2.5 inch exhaust manifolds and pipes? Was this considered to be what was referred to as "Off Road Exhaust" in 1964?

Thanks in advance for replys

Jeff

All 63-64's with 250 HP and all 63-64's 300 HP with Power Glide used a 2" system.

All 63-64 300 HP and higher engines used a 2 1/2" exhaust system.

There was also an "optional off road" system available. That system also had 2 1/2" pipes.

[Jeffrey B.]

Re: 1964 exhaust question

Guys,

Thanks for the additional information. I understand that the mufflers used as part of the N11 option had 3 baffles where the standard mufflers had 5 baffles.

Jeff

[Alan D.]

Re: 1964 exhaust question

Jeff, I think of a baffle as a wall in way of the direction of exhaust travel. Not being a muffler guy that may be a wrong assumption.
The N11 muffler - if you look into the 2" exhaust opening one can see the 2 1/2" inlet pipe, ie nothing in the way, straight thru.

[Dan H.]

Re: 1964 exhaust question

Jeff, I think of a baffle as a wall in way of the direction of exhaust travel. Not being a muffler guy that may be a wrong assumption.
The N11 muffler - if you look into the 2" exhaust opening one can see the 2 1/2" inlet pipe, ie nothing in the way, straight thru.

Alan, are you sure? I remember my C1 off roads were straight through but I just received a very nice N11 exhaust from Gardners for my 64, they did extensive research etc. as others have, and it has a 'baffle' so you can't see straight through it, can see light but it diverts around abit befor exiting etc. I was under the impression there were fewer 'baffles' in the N11 than the stock mufflers.
Dan

[James G.]

Re: 1964 exhaust question

Dan, you are correct. Fewer baffels and 2.5 inches inlet. Gardner bought NOS Mufflers for a friend so they could have his 'original', but full of holes examples to completely replicate as best as possible the N-11 muffer.

[Alan D.]

Re: 1964 exhaust question

Well all I can say is that the N11 on the car are the service replacements purchased around 1970/1 (can look up date if needed), so I'm not saying anything beyond my example.
If one shins a light into the exhaust pipe you can SEE the bend of the inlet (2/ 1/2 pipe). I then measured the distance to verify. Now in order to get some pictures it may take a little trail and error - I'll work on it.

Idea; did later "off road" Service parts undergo a modification (baffles) due to EPA noise levels or some other government "better idea". Notice every time I think a corvette problem is solved along comes another but. Would think the part number could have changed???

[John H.]

Re: 1964 exhaust question

Idea; did later "off road" Service parts undergo a modification (baffles) due to EPA noise levels or some other government "better idea". Notice every time I think a corvette problem is solved along comes another but. Would think the part number could have changed???

Not likely. The part numbers for the LH (3845735) and RH (3845736) N-11 assemblies never changed, and the production-line parts and service parts had the same part numbers. The N-11 assembly (muffler and full-length welded intermediate exhaust pipe) was only available as a welded assembly for service; all other service mufflers were just the muffler, with the short curved inlet pipe to be clamped to the cut-off end of the intermediate exhaust pipe.

A later drawing change specified that only the service assembly was to have the part number and date code embossed on the outer wrap of the muffler shell.

[Dan H.]

Re: 1964 exhaust question

Well all I can say is that the N11 on the car are the service replacements purchased around 1970/1 (can look up date if needed), so I'm not saying anything beyond my example.
If one shins a light into the exhaust pipe you can SEE the bend of the inlet (2/ 1/2 pipe). I then measured the distance to verify. Now in order to get some pictures it may take a little trail and error - I'll work on it.

Idea; did later "off road" Service parts undergo a modification (baffles) due to EPA noise levels or some other government "better idea". Notice every time I think a corvette problem is solved along comes another but. Would think the part number could have changed???

Alan, you're correct about no 'baffles' in the 2" pipe that goes all the way forward to the other end plate on the muffler itself. The pipe has perferations etc. in it, can't tell what's in the middle but the 2 1/2" inlet pipe goes into the muffler about 10" to a 'baffle' which looks like the exhaust can then go back around to the end of the 2" outlet pipe. NOT MUCH restriction. Gardners system comes with the muffler separate so you can center everything then weld up to the short stub on the muffler, should look very nice then! Just slop on some tar based preservative and you're in!
Dan