Alan Young
Member
has anyone used a GM TH350 behind a 318 cu in engine? If so what adapter did you use and where did you get the adapter?
Transmission swap
- Thread starter Alan Young
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Professor Fate
Push the button, Max...
318-350 AT (wilcap.com)
Currently sold out. Not even sure it would fit an A body floorpan/crossmember without major mods.
200R4s are a bit more common of a swap to gain the overdrive in limited spaces. Look to SilverSport transmissions for info on that.
Currently sold out. Not even sure it would fit an A body floorpan/crossmember without major mods.
200R4s are a bit more common of a swap to gain the overdrive in limited spaces. Look to SilverSport transmissions for info on that.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Seems like a lotta work for no real gain. Unless you blew up the last Mopar trans in the history of Mopar.
Mopars:
A904; 2.45-1.45-1.00
A727; same as A904
A518; 2.45-1.45-1.00-.69od, and LU
A999; 2.74-1.54-1.00 ------ and LU
A998; could have either ratio, and with or without LU
A500; 2.74-1.54-1.00-.69, and LU
GM overdrives:
4L80; 2.48-1.48-1.00-.75
200R4; 2.78-1.50-1.00-.67
700R4; 3.06-1.63-1.00-.70
4L60 ; same as 700R4
I think all of these have LockUps
>Larger gear splits, like the A999/A500/700R4, are know as wide-ratio transmissions.
>Smaller splits like the A904/A727/A518/4L80 are known as close-ratio transmissions.
>The 200R4 goes up the middle, and has a great overdrive
>The A500/A518 comes with the same drop-down od. Either of these are excellent street transmissions, allowing deep rear gears, even up to 4.56s, which in overdrive become like 3.15s.
--------------
Say with 4.30s, the A500 gets a starter-gear of 11.78 and a hiway gear of 2.97 for 65=2400 in LU with 27" tires. This is about perfect for working the ignition timing out, for optimum fuel economy, which is about 52 to 56*. With a starter of 11.78, you do not need much of a stall, to get moving, and the 4.30s will have you bang-shifting. The stock convertor will act like a fully automatic 2-speed transmission, starting with a hydraulic ratio of about 1.8, and finishing at about .95 as speed builds. Thus, your 4-speed auto behaves like a 5 speed. and the LU adds a half-gear at cruising, by eliminating the last bit of TC slip.
All this torque-multiplication, makes your small engine feel like a larger one, so you can de-cam it some, with an eye towards fuel-economy in these times of high-priced gas. Also, because the gear ratios reduce the load at typical street-legal speeds, you can push the cylinder pressure up higher and a lil closer to the detonation limit, which will increase your engine efficiency under all conditions, again saving you money at the pumps, by driving further on a gallon of gas.
BTW
the early 5.2 injected Dakotas came with 3.91s........... and this makes a great package with the A500. The starter is 10.71 which is more than adequate, and 65=2180 in LU. With EFI the factory had the cruise-timing thing handled; but with a distributor, it would be very difficult to give the engine the last bit of timing it would want. To optimize it, you would need a stand-alone computer, or, at the least, a dash-mounted, dial-back, adjustable timing module. Mine has a range of 15* and easily covers the shortfall. This device can also overcome any problems you might encounter with too much cylinder pressure...... if you had gone in that direction. I set mine around 60% which gets me up to 6 addition degrees of advance, or up to 9 degrees of retard. Setting the cruise-timing is now like shooting an elephant with a shotgun, I can't hardly miss. And I use the extra advance right after it fires up from a cold start, which idles it up enough that it doesn't need no stinking choke, lol. Full retard idles it down to under 4mph for parading and takes away the jumpiness, with a manual trans.
Happy HotRodding
Mopars:
A904; 2.45-1.45-1.00
A727; same as A904
A518; 2.45-1.45-1.00-.69od, and LU
A999; 2.74-1.54-1.00 ------ and LU
A998; could have either ratio, and with or without LU
A500; 2.74-1.54-1.00-.69, and LU
GM overdrives:
4L80; 2.48-1.48-1.00-.75
200R4; 2.78-1.50-1.00-.67
700R4; 3.06-1.63-1.00-.70
4L60 ; same as 700R4
I think all of these have LockUps
>Larger gear splits, like the A999/A500/700R4, are know as wide-ratio transmissions.
>Smaller splits like the A904/A727/A518/4L80 are known as close-ratio transmissions.
>The 200R4 goes up the middle, and has a great overdrive
>The A500/A518 comes with the same drop-down od. Either of these are excellent street transmissions, allowing deep rear gears, even up to 4.56s, which in overdrive become like 3.15s.
--------------
Say with 4.30s, the A500 gets a starter-gear of 11.78 and a hiway gear of 2.97 for 65=2400 in LU with 27" tires. This is about perfect for working the ignition timing out, for optimum fuel economy, which is about 52 to 56*. With a starter of 11.78, you do not need much of a stall, to get moving, and the 4.30s will have you bang-shifting. The stock convertor will act like a fully automatic 2-speed transmission, starting with a hydraulic ratio of about 1.8, and finishing at about .95 as speed builds. Thus, your 4-speed auto behaves like a 5 speed. and the LU adds a half-gear at cruising, by eliminating the last bit of TC slip.
All this torque-multiplication, makes your small engine feel like a larger one, so you can de-cam it some, with an eye towards fuel-economy in these times of high-priced gas. Also, because the gear ratios reduce the load at typical street-legal speeds, you can push the cylinder pressure up higher and a lil closer to the detonation limit, which will increase your engine efficiency under all conditions, again saving you money at the pumps, by driving further on a gallon of gas.
BTW
the early 5.2 injected Dakotas came with 3.91s........... and this makes a great package with the A500. The starter is 10.71 which is more than adequate, and 65=2180 in LU. With EFI the factory had the cruise-timing thing handled; but with a distributor, it would be very difficult to give the engine the last bit of timing it would want. To optimize it, you would need a stand-alone computer, or, at the least, a dash-mounted, dial-back, adjustable timing module. Mine has a range of 15* and easily covers the shortfall. This device can also overcome any problems you might encounter with too much cylinder pressure...... if you had gone in that direction. I set mine around 60% which gets me up to 6 addition degrees of advance, or up to 9 degrees of retard. Setting the cruise-timing is now like shooting an elephant with a shotgun, I can't hardly miss. And I use the extra advance right after it fires up from a cold start, which idles it up enough that it doesn't need no stinking choke, lol. Full retard idles it down to under 4mph for parading and takes away the jumpiness, with a manual trans.
Happy HotRodding
Last edited:
Charrlie_S
Well-Known Member
I agree with PF. Why go thru the hassle of swapping a 3 speed auto for a different brand 3 speed auto. No gain in doing that. By using the 200R4 you gain overdrive and lock converter. But it is still a fair amount of work. A friend of mine has a 200R4 behind a turbocharged FI slant six, and loves it.
CudaFactHackJob
Well-Known Member
Why not put an LS motor in it?
C130 Chief
Mechanical Genius
There are a whole lot more Chevy bolt pattern 904's out there than TH350's adapted to LA motors.
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