TH350 behind the 225 Buick

Thanks for all the great feedback on the TH350 conversion. It looks like the way I'll be going as soon as I sell my SM420 2, Advance D18 adaptor kit,
swing pedals, and new master cylinder w/hydaulic slave clutch actuator.

By the way, both Novak and Advance are pretty helpful if you call them with questions. Best thing with Novak is that I can get a Novak rebuilt TH350 mated to a rebuilt D18 for about $1300.00(and my D18 needs rebuilding!).

 

Thanks guys for all the feedback, I know I did not start the thread but I really had thought about this a lot before. To me the overdrive was the sticking point. I was going to ship my tranny, tcase,overdrive to herm in August, seems now I am going x the tranny and start to source conversion parts for the Auto set up.
Here is a huge setup, the flywheel, I hear the 225 needs a special way to balance the flywheel. (?) where would you get a flywheel to match it and the 350?

 

Interesting question- I have run several 225s with auto flexplates and never had a problem. Does anyone have any other info?

 

I have a standard flex plate between my 225 and TH350. I used the 4x4 tranny into a Dana 300 with Novak adapter. I don't have any issues with driveline length because mine is in a CJ6. I did modify my pan slightly just as a precaution and I adjusted my front bump stops to keep the driveline away from the pan. I reall want to change the front drive line to a two piece with a ppillow block someday.

Not sure what stall mine is?................The only thing I have done since I built it was change the coller to a better design with a pull fan. Thermo is set ot 180 but rarely ever gets there.

 

You need either a 225 flex plate like from a Jeepster Commando or an oddfire 231 flex plate. The Even fire 231 is balanced different.

Flywheel is different from a flex plate. Flywheel is generally much heavier and has a mounting surface for the clutch assembly. Flex plate is thinner and simply has a ring gear for the starter and acts as a transfer medium to the torque converter.

 

OK, I will be commiting toi this in the spring and have been shopping for a th350
a question has arrived
there is 2 bell housing versions
the regular and the BOP
anyone know if both work or does one need an adapter?

 

Disclaimer - I've never done it - but I would think the viscous dampening of a torque converter would balance it all automatically.

 

Interesting thought, but it doesn't work that way in practice. All the externally balanced engines (ie 225, 231, 304, 360, 401, etc) have their own flywheels and flex plates with a specific balance.

 

I bought a 70 dollar adapter plate from jegs for the bellhousing difference since I already had a th350 from a chevy truck. It has worked fine.

 

Believe this is the best way to go, GET the 4x4 ("K") case. This case has the heavier casting in the back for supporting a Xfer case. The 4x4 will also already have the "short shaft", this will allow for a bolt-on adapter but will be longer. If the short shaft isn't used, the trans needs to be torn apart and a new output shaft installed.

This was a while ago and things may have change:
The AA adapter has some issues with U-Joint and a 350. One of the small V-6 style U-joints must be used OR I've seen full size used but grinding on the case was needed. AA adapter also required "some" trans pan mods, mostly just a little clearancing with a hammer.

Novak, seen these used but never done one. Novak will allow the large U-joint but push the Xfer back an extra 2ish inches. The conversions I saw also needed more pan modification than just some tapping with a hammer.

Overdrive and an auto, it works. I really didn't like the way it shifted, mine shifted up but couldn't get it to shift down while moving. Wasn't that big of a deal because you usually don't stop on the highway.

Torque converter, just stock, it's good all around. Heard of th400 converters used but never driven one.
You can also use a 700r4 1st gear drum with a TH350 output gear welded to it for the 3.06 first gear. There is very little about this on the net but have talked to a shop that has does these.

 

thanks bob, great reply

 

Dont forget trans cooling issue as well.

The K case is a bit harder to find and wont be BOP.FWIW.

 

X2 on all of this. Mine shifts kinda odd also but it works well. At the time i did have access to a BOP th350 but the shaft change was daunting at best on my own and at the time I was on a budget. I don't think the strength thing is that big a deal in such a light vehicle.

 

Ok i have been following this thread, but what driveshafts did you guys use? Did you modify the current or go with aftermarket like what Tom Woods makes?

 

Almost every trans/transfer swap is going to change the length of your drivelines. Any local driveline shop can re-tube a shaft. The benefit of Tom Woods is that they understand what Jeep people need. Remember that drivelines should be one of the last things you make once your project is sitting on its wheels with all the weight on the springs.