I was told that the powerglide, th350 and the 700r4 transmissions all used the same covertor. It seemed strange to me,so I tried to confirm the info on the web, only to find nothing. Anyone know for sure are the covertors the same? I currently have a rebuilt 3000 stall pg and I am going to swap in a th350, it would be great if the convertors are inchangeable. I originally wanted to put in a 200r4 but its seem to be alot more work than the 350.
Thanks

johnson,
The Powerglide convertor is different than the th350 and the 700r4. The th350 and the th400 use
the same convertor. The 700r4 uses a lockup convertor.

I am told the with the 200r4, you have to shorten the dirve shaft, move the transmission mount and play with the tv cable and lockup wiring. This seem a lot more involved than the th350.

What is this going into? But anyway the power glide and SHORT shaft T350 the drive shaft will remain the same. any others the drive shaft will need some changes made.

It is in a 65 acadian with a 6L Just looking for better all transmission

The easiest upgrade is the short TH350. It will require the removal of the front lip of the trans cross member to clear the pan, but everything else is simple.

The 200 should be able to use the stock crossmember and drive shaft, but will require a tv cable and a lock-up wiring kit with the convertor or a non-look-up converter.

The 700 requires the same as a 200 plus a new trans crossmember and a shorter drive shaft.

The 350 is definitely the easiest upgrade and you may be able to trade your PG for a 350 as in most places the PG is harder to find.

The real question is what do you mean by a better transmission? The PG is good reliable unit, a 350 will give a little more performance and either of the R4s will gain some performance and with the OD maybe better economy. It is a matter of how much do you want to spend, how mechanically adept are you and what other mods are in your plan.

The 250 has had quite a bit of work done to it. The pg seem to be very slow starting off so I thought that if I was going to change the trans, then the 200r4 would be the best. But that seems to be a lot work trying how to hook up the TV cable, to a holley 4 barrel that is sitting crosswise on the intake and get the wiring for the lockup convertor. You mentioned a non lock up convertor. Is this still an overdrive trans, and how good are they, what cars did they come in. Thanks for the info

johnson,,,,

If you could, I would install the 200R4.
Better gearing,gear spacing.
700R4 has bad gear spacing.
200R4 has taller overdrive gearing.

A nonlockup converter is used in the same trans,it just will not lock-up & give you the better gas milage as a lock up converter would..
200R4's came in Buick Grand nationals, V-8 Chevy's,Pontiacs,lots of cars,etc, just make sure you get one w/the Chevy bolt pattern.

They are good tranny's, many Buick GN guys put a lot of abuse to them w/a turbo.

Normally aspirated inline Chevy, no problem!!

What rear axle gear ratio do you have?

MBHD

The car currently has a 308 gear

johnson,,,,,,,


Tell us about your build on your 250,if you don't mind?
What vehicle is it in, weight,etc?

MBHD

It is nothing special. Chevy 250 ci, circle track head with recessed head bolts,and dividers removed, with 350 chevy valves, screw in studs and roller rockers. It has a crane cam, (forget the specs) offenhouser 4 barrel intake, holley 390. Split exhaust manifold and true dual exhaust. HEI distributor. Nothing really different. We had purchased everything to go to a sbc 4 speed, but change our minds.

johnson,,,
What kind of car is this engine in?
Vehicle weight?

Thanks
MBHD

65 chevy 11, don't know the weight

Figure the car weights ~3000 lbs. Unless you are going to change the rear axle ratio, in my opinion you do not need an od transmission.

Just for grins, here is a list with transmission gear ratios http://www.teufert.net/trans/tran-rat.htm

Also, here is a high gear rpm calculator for PG/TH350, 200r4 and 700r4: http://www.700r4.com/speedoCalc/rpmcalc.php

Correct, w/a 308 rear gear you do not need an OD.
But w/a OD trans you can gear it low like 373's.
I would say 411's,,, but,,,
I know it's kinda hard to fit taller & wider tires in those 65 Nova's unless you modify it.

Six cylinders need all the gearing you can get compared to a Bigger V-8.

So in my opinion, I would install 373's w/a 200R4.
Best combo to take off quick & still run great on the freeway.
I would also run a 3000 stall converter w/a lockup torque converter.
Just my two cents
Goodluck!!!

MBHD

A taller tire is not so much the issue as it is Getting a WIDER tire in the well,In the rear.I have ran a 29x15 in the stock wells.BUT like i said you have to watch the width.And if your running a after market rim You also have to pay close attention to the offset/Back spacing.But there is one trick most due to get a wider tire in the well and that is to remover The axle bumpers off the frame This will give you about another 2inchs of back space or offset.

Johnson, I drive a 68 Camaro 250 with HEI Clifford intake and headers also a Holly 4 barrel. This engine has over 160,000 miles. The second best thing Iv'e done is install a used 700r4. The cost of drive shortening ($125) and the aftermarket rear mounting bar($175) was well worth it. The low 1st gear really gets off the line, ans in OD I tach 2000 at 70 MPH. I kept my 3:08 rear so I could see if it would be a problem, so far so good. Check out bowtieoverdrives.com lot of good info there. Good luck Herb

Herb
Did you have a problem with the tv cable and the lockup convertor. I can see that the lockup convertor can be handled by the aftermarket kits. The TV cable could be a lot bigger problem as my carb sits accross the motor. What did you use for the cable and bracket?
Thanks Larry

A 700R4 is a decent tranny, I just do not like the big drop between first & second gear,(makes your engine drop out of the power band)OK if you are boosted(turbo,blower), but for a normally aspirated small six cylinder engine,,,,a 200R4 is a better choice.

MBHD

MBHD,

From one of your earlier posts above, you didn't say that a non-lockup converter will provide better gas mileage than a lock-up converter, did you?

Assuming that you do the tricks to lock-up the converter on higher gear(s) and speeds, that “direct-drive” will offer much better efficiency then the “fluid coupling”.

Just to share a market trend on bigger rigs, newer Allison – automatic/electronic - transmissions used by transit busses, trucks and RV’s are able to lock the converter in all (six) gears, unlocking it for a fraction of a second during gear changes.

Roc On The Rocks,,,
I said you would not get better gas milage w/a non-lockup converter.

The Allison trans is great,,,, but it's too big to fit in our vehicles.
That thing is a monster!!

MBHD

Johnson: I used the Lokar TV cable from Lokar performance products. The bracket I used for my T350 was a Holly Item, I just used 1 1/4 washers with a small hole for the TV adjustment nuts. Because I have column shift I used a Kugel shift lever. The big dif. between 1st and 2nd can be either fast get a way or "feather" the pedal for smoother shifting. I just tightened my TV cable a taste for later shifting, obviously I'm still learning how to use my new add on! Good luck Herb

The lockup converter is no problem to hook up. If you go with that I can send you directions on how to do it. Joe