Exhaust: 700R4 interference?

[drrotor]

Restoring a '61 Hawk which is all original, 289, stock rear end, etc, but I'm in the process of converting it to a GM 700R4 automatic. I was going to order an exhaust system from Parks Pipes or Silvertone, which is made to bolt in to a stock car. Anyone happen to know whether or not there is a fitment problem when doing this?
Additionally, I'm going after a really quiet car with this particular build-- any muffler recommendations? Silvertone offers stainless, which I'm leaning towards... however if I have to modify, I can weld mild steel. Perhaps I can also weld stainless with my MIG...

[sweetolbob]

My 54K needed some massaging on the top of the tunnel at the firewall but I used an SBC. As far as exhaust, get the Silvertone SS, it will last and probably not much more than the steel one. As far as welding SS with a MIG. Just get some 308 wire and you'll be surprised at how well it runs. I prefer welding stainless to mild steel just seems to run better for me.

I also had to raise the tunnel between the seats but again I don't know 61 Hawk's, anyway whatever it takes it will be worth it. Just bolt it to the engine and slowly raise the trans. It will let you know.

Ask about the sound of Don's quietest here as I believe they are all glasspacks. You may want to order SS mufflers separately from another source for real quiet mufflers.

Bob

[wdills]

I have the quietest mufflers Don (Silvertone) offers. They are not terrible but still louder than I wanted and they have a bit of a drone at certain RPM. I would recommend getting a different muffler if you want a really quite car.

[acolds]

I have Dons quiet mufflers on my Clipper and I think they are to loud compared to old stock system but the fit was perfect

[64V-K7]

. Anyone happen to know whether or not there is a fitment problem when doing this?
Additionally, I'm going after a really quiet car with this particular build-- any muffler recommendations? Silvertone offers stainless, which I'm leaning towards... however if I have to modify, I can weld mild steel. Perhaps I can also weld stainless with my MIG...

I don't know if Don makes a set of pipes to fit around a 700R4, however the 700 has a larger pan than an FOM. So the exhaust route has to widen out earlier to get around the pan. My Avanti was converted to a 700R4 and all I did was take the first intermediate pipe, which is just after the manifold downpipe, swap ends and have the neck swedged (expanded) to fit over the manifold pipe. That allowed the exhaust route to clear the 700 trans. The hole in the X-member also had to be expanded a bit, but you won't have that issue.

[PackardV8]

they have a bit of a drone at certain RPM.

V8 dual exhausts will develop a resonance at certain RPM. Back in the day, GM eliminated it with cannisters at the very end of the system. Ford eliminated it via a crossover H-pipe between the two downpipes before the mufflers. I always use an H-pipe.

jack vines

[bensherb]

Wheather it will clear your trans pan will have a lot to do with how your trans is mounted. The tailshaft of mine, '62 GT, is on a stock GM mount and mounted on top of the "wing" crossmember. If my stock type replacement exhaust (it was on the car when I got it) had been installed in the correct location it would have almost cleared the 4L60 pan. The left would clear, but the right needs to drop below the kick up in the "wing" and move a bit outboard. As badly as my exhaust was fitted, I had to flatten about 10" of pipe about 1/2" deep where it runs under the trans pan. In these pics you can see how my exhaust crosses the edge of the trans pan, and how the kick up in the "wing" is blocked by the trans. I think the clearance issues could easily be eliminated by minor rotating/relocating of the pipe before welding it to the head pipes. (Yes Rich, I know the factory left pipe should go over the "wing".) With this Trans there is plenty of room for the left pipe to go over the wing. Not so with the original OD, it would be very tight around the solenoid.


This working but clumbsy exhaust will soon be going away for a better fitting 2 1/4" SS one.

Welding stainless with mig is no sweat, but practice a bit, the settings will differ from similar weight mild steel. Gas choice will make a big difference too, C02 will work, but not the best and welds are usually uglier. A tri-mix gas like 90%He/7.5%Ar/ 2.5%CO2 is a better choice.

[drrotor]

Well today I ordered a SS exhaust system including mufflers from Myer Studebaker in Ohio. According to Jon Myer, there is no interference issues with this system. Since they sell their very own 700R4 conversion kit, I would imagine they’d know whether it fits or not. We shall see. It will be some time before it arrives and gets installed, but I will post my impressions then. Thanks for all your help!

[345 DeSoto]

I installed 200-4R behind the 289 in my Sky Hawk and my Parks Pipes fit like Factory with no modification...