powerglide
Thread Starter
2nd Gear
Joined: Feb 2021
Posts: 2
Likes: 0
powerglide
I own a 1963 convertible equipped with a low hp 327 engine. It currently has a muncie 4-speed and I would like to switch it to an automatic trans. I tried a th350 but it would not fit without modifying the exhaust and crossmember to fit. Has anyone made this switch either using an original powerglide or some other automatic trans ? HELP!
Melting Slicks
Joined: Apr 2012
Posts: 3,070
Likes: 866
From: EHT NJ
I own a 1963 convertible equipped with a low hp 327 engine. It currently has a muncie 4-speed and I would like to switch it to an automatic trans. I tried a th350 but it would not fit without modifying the exhaust and crossmember to fit. Has anyone made this switch either using an original powerglide or some other automatic trans ? HELP!
https://www.google.com/search?q=puti...hrome&ie=UTF-8
Burning Brakes
Joined: Feb 2015
Posts: 766
Likes: 179
From: Vancouver BC
Hi Tom,
The TH350 is a direct swap for a Powerglide. I did this swap in my '67 and the installer didn't have to move the motor to get the TH350 installed. I didn't have to modify the exhaust, and no crossmember mods were needed as the TH350 rear mount is in the same location as the PG mount. Note that the TH350 was introduced in1969 as a 3-speed replacement for the PG, and is nearly identical in length. That meant it was directly compatible with existing PG auto trans mount locations on existing car frames of the day.
Read post #15 in this thread where I explain more about my PG to TH350 swap: https://www.corvetteforum.com/forums...onversion.html
Note the '63 is a slightly different bird with regards to the auto shifter linkage. I believe Shiftworks may still sell a kit to adapt your stock shifter to work with the TH350. Call Herb Gray at Shiftworks - he was very helpful during my swap..
Hope this helps.
Alex
The TH350 is a direct swap for a Powerglide. I did this swap in my '67 and the installer didn't have to move the motor to get the TH350 installed. I didn't have to modify the exhaust, and no crossmember mods were needed as the TH350 rear mount is in the same location as the PG mount. Note that the TH350 was introduced in1969 as a 3-speed replacement for the PG, and is nearly identical in length. That meant it was directly compatible with existing PG auto trans mount locations on existing car frames of the day.
Read post #15 in this thread where I explain more about my PG to TH350 swap: https://www.corvetteforum.com/forums...onversion.html
Note the '63 is a slightly different bird with regards to the auto shifter linkage. I believe Shiftworks may still sell a kit to adapt your stock shifter to work with the TH350. Call Herb Gray at Shiftworks - he was very helpful during my swap..
Hope this helps.
Alex
Le Mans Master
Joined: Nov 2015
Posts: 7,444
Likes: 2,625
From: Really Central IL Illinois
There were a couple of different length TH350s. I believe the ones used in trucks were longer. Could it be you have a longer one?
I have 3 PowerGlides and a TH350 in a storage trailer and they are all the same length.
I can see that the exhaust pipes may need to be tweaked to clear the back of the TH350.
I have not done the swap in a C2, so take this as information good or bad.
I have 3 PowerGlides and a TH350 in a storage trailer and they are all the same length.
I can see that the exhaust pipes may need to be tweaked to clear the back of the TH350.
I have not done the swap in a C2, so take this as information good or bad.
Burning Brakes
Joined: Feb 2015
Posts: 766
Likes: 179
From: Vancouver BC
Three different tail shaft lengths (6", 9", and 12") are used to adapt the TH350 transmission to the vehicle its being installed in. Powerglides used 2 different tail shafts, 6" and 9".
The tail shafts are interchangeable and can be removed without distributing the main transmission body.
This drawing summarizes this nicely:
As you can see, the Powerglide and the TH350 share the same 22 1/4" length from front of converter housing to rear transmission mount.
A TH350 with a 6" tail shaft is the same overall length as a Powerglide with a 9" tailshaft, as used in the C2 Corvette.
As the overall length of transmission and tail shaft is the same, and the rear mount is in the same position, a TH350 is a direct bolt-in swap for a Powerglide,
Le Mans Master
Joined: Nov 2015
Posts: 7,444
Likes: 2,625
From: Really Central IL Illinois
That's interesting, because I swapped a TH350 into a 64 El Camino that had a factory Powerglide and did not have to shorten the driveshaft. Not saying it should not have been shortened, but never had any problems.
The chart shows the shortest TH350 is 27-5/8" while the shortest PowerGlide is 25-5/16". That 2-5/16" of extra length would appear to require the driveshaft in a C2 (and other cars) to be shortened to do it correctly..
If the chart is correct, the mount is in the same position, and I recall it is.
It very well may require exhaust pipe modifications as the width of the automatic is greater just before the cross member.. Indeed, checking one of the supporters sites show different pipes for the manual and automatic.
The chart shows the shortest TH350 is 27-5/8" while the shortest PowerGlide is 25-5/16". That 2-5/16" of extra length would appear to require the driveshaft in a C2 (and other cars) to be shortened to do it correctly..
If the chart is correct, the mount is in the same position, and I recall it is.
It very well may require exhaust pipe modifications as the width of the automatic is greater just before the cross member.. Indeed, checking one of the supporters sites show different pipes for the manual and automatic.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Burning Brakes
Joined: Feb 2015
Posts: 766
Likes: 179
From: Vancouver BC
That's interesting, because I swapped a TH350 into a 64 El Camino that had a factory Powerglide and did not have to shorten the driveshaft. Not saying it should not have been shortened, but never had any problems.
The chart shows the shortest TH350 is 27-5/8" while the shortest PowerGlide is 25-5/16". That 2-5/16" of extra length would appear to require the driveshaft in a C2 (and other cars) to be shortened to do it correctly..
If the chart is correct, the mount is in the same position, and I recall it is.
It very well may require exhaust pipe modifications as the width of the automatic is greater just before the cross member.. Indeed, checking one of the supporters sites show different pipes for the manual and automatic.
The chart shows the shortest TH350 is 27-5/8" while the shortest PowerGlide is 25-5/16". That 2-5/16" of extra length would appear to require the driveshaft in a C2 (and other cars) to be shortened to do it correctly..
If the chart is correct, the mount is in the same position, and I recall it is.
It very well may require exhaust pipe modifications as the width of the automatic is greater just before the cross member.. Indeed, checking one of the supporters sites show different pipes for the manual and automatic.
I didn't have to modify the exhaust pipes either. The left side head pipe is closer to the trans pan than it was with the Powerglide, but this hasn't caused any issues.
Here's a picture after the swap, showing the location of the TH350 trans pan in relation to the head pipes.
The tight fit between the left head pipe and the transmission pan hasn't caused any problems. I've used an IR gun to check the pan temperature and it never exceeds 200F even in hot weather, idling in traffic.
Le Mans Master
Joined: Nov 2015
Posts: 7,444
Likes: 2,625
From: Really Central IL Illinois
Exactly what the OP needed.
As I recall, the PowerGlide has a sqare pan so I am surprised the TH350 was a tighter fit, but I don't know the dimensions of either.
As I recall, the PowerGlide has a sqare pan so I am surprised the TH350 was a tighter fit, but I don't know the dimensions of either.
Last edited by R66; Feb 24, 2021 at 09:28 PM.