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I just bought a low-mileage 1969 convertible in great shape - it's my first Corvette and I'm having a lot of fun with it.
I'm considering converting my side exhaust to rear exhaust. The side pipe covers are barely hanging on to the body and fixing that may be tricky or not work very well.
Also, the sleak look of the C3 profile without side pipes appeals to me and a Monaco Orange C3 convertible is eyecatching enough without em!
Anyone have experience doing this? Is this a mistake? Is it expensive? Is there a lot of body work on the rockers and lower rear panel? Difficult to match paint?
I’ll start by saying welcome and follow up by saying that it’s never wrong to do what is to your taste on your car. Others may disagree, but it’s your car.
You might want to post up a pic or two to figure out which side exhaust system you have. The stock style with covers are potentially quite valuable if you choose to sell them. Some of the aftermarket ones should just be tossed.
You’ll likely have to replace your exhaust manifolds with stock types or headers, the latter will provide better performance. Also, you may or may not have cutouts on the rear valence. If you want it to look stock, that change is a bit of a chore. You could always just turn down the tailpipe. Again, post pics to get a better answer.
Rookie advice...IF you REALLY like the looks of rear exhausts.....search the Vendors on the right side of this page for prices of rear exhausts.
IF the exhaust panel below the rear bumpers does not have the cut-outs for exhaust tips, you will need to do bodywork in order to allow the exhaust tips to exit. Check the cost of a panel.
IF the rocker panels have been cut or notched to adapt the side pipes, you will need to replace the notched panels...check the cost of replacement panels.
Add in another $500+ for professional bodywork & paintng.
Here are pics of the fragile state of the side pipe covers. An experienced mechanic is going to try to shore them up but we’re not sure how that will go.
I'd be in agreement that the side exhaust is not original.
The rear fenders have the cut outs for the the under car exhaust and the the lower valance panel is an aftermarket part the has "wings" that cover the hole in the fender. Your solution is to find an under car exhaust valance panel, have it painted to match, bolt it on, install the under car exhaust, and acquire/install the stock rocker panels. The side exhaust parts can be stored or sold to recoup some of the cost associated with converting back to under car exhaust.
1 big disadvantage of going to under car exhaust, is that you'll get a lot more cabin heat. Small block?, maybe not a big deal, but with my '69 BB, it is a big deal.
Like quoted above, it a lot of work and $$ to change it. I would fix it. Looks like some big fender warshers would help a lot, and when painted, they would hardly show.
Also, try to see what kind of mufflers you have. If you have reverse flow mufflers, they are very restrictive and you should change them out.
It is difficult to say with the side exhaust covers in place, but it appears that all of the mounting points are present for the rocker moldings. Even if the fiberglass has been trimmed for the side exhaust, the rocker moldings are going to hide any area that was cut as long as the mounting points for the rocker screws are all present. Point of note, the screws often become rusted in place and snap off when removed so it may be necessary to drill/re-tap the mounts in the body (preferred) or replace them. This may be the reason why several screws seem to be missing. There are also four mounting points (two per side) on the lower part of the rocker (body) area that mount the rocker molding. On a well used car, these are often damaged or missing and it's tough to say if your have been removed or are damaged as I just mentioned. A photo of this area could provide the answer.
Edited to say that I took a look at the body on my own 1969 and it appears that the forward most mounting point for the rocker molding may have been removed. Best bet is to get an old molding and match up the holes to be certain what is there and what needs to be there. Even it has been removed, there are ways to address it without resorting to body work.
The ONLY area that would be noticeable (if it was cut) is the area in the rear wheel well that covers the top of the frame. These "caps" were removed on real side exhaust cars, but remain on under car exhaust cars. That would be the only area (outside of painting a new rear valance) that would require more than just a bolt on solution. My guess is that they are still there... Looking at the way it was added, your car appears as though the owner just wanted the side exhaust... He wasn't trying to convince someone that it was original to the car.
Regards,
Stan Falenski
Last edited by Rowdy Rat; 05-18-2023 at 12:41 PM.
Reason: Correction/additional information
As far as heat goes, do you want your left leg to be warm... Or your right leg? That's about the only difference you're going to see in making the change. Many owners put in a heat barrier to keep the cabin better insulated so that is always an option as well.
One other point to keep in mind is that with the side exhaust, the rear suspension and the area behind it is very easy to access... With an under car system, not so much.
Rowdy Rat is 100% correct about the access issue. It takes a little more effort to safely lift one with a floor jack but once you do the access to to the rear suspension, transmission and gas tank is greatly improved. I’ve had them both ways and I would rather have the factory style side exhaust.
If I remember correctly the factory side exhaust cars the frame is different. I think with OEM rear exhaust the frame had holes for the pipes to go thru to get to the rear of the car and the side exhaust cars didn't..
Also if you decide to go to rear exhaust and the rear panels are OEM without the cutouts buy new reproduction rear panels and to replace the OEM ones and sell the original OEM without the cutouts as those can bring some good money to the right person wanting original.
Looks like whoever installed these screws had their drill set on Max and blasted them through the shielding! Way to much torque! Some look some screw heads are snapped off. Will take some patients to get it rite and looking waybetter. Nice looking side exhaust on your vette, I have the standard rear exhaust on my 69.
Mike
Frame should be the same. I'll bet the exhaust hanger bracket is still mounted at the rear trans mount. Rear valance indicates car originally had undercar exhaust.
Frame should be the same. I'll bet the exhaust hanger bracket is still mounted at the rear trans mount. Rear valance indicates car originally had undercar exhaust.
YUP, you are right about the rear valance. I missed that in the pic's. My 69 N14 factory side exhaust car does not have the curve in the seam.
I still think that the N14 factory option had a different frame. I will have to check into that further and will look at mine when I get an opportunity
to get to where it is stored.
05-18-2023, 10:50 AM
Side exhuast vs rear exhaust
