[455-4+1]

I have just pulled the Hydro out of my 63 Cat, which is toast. The dampener plate was shot as well. I do have another plate, and a replacement trans.....unknown condition..

A BOP TH350 has popped up over here in NZ, and I was wondering if they are much smaller case size than the TH400. I realise the TH400 (I have several BOP versions) wont fit without beating up on the tunnel. I would prefer not to do this if possible !!!.

Just thought the TH350 could be a worthwhile upgrade to the Slimmy Jimmy.
I may be modifying the crossmember to fit a new dual Ex better so that's not an issue in that area

Any idea if it will fit without beating on the trans tunnel or any other areas ??

Thanks

[rosconz]

I got a slim jim(free) from a guy in Wellington as a spare for my 63 Cat, he fitted a TH400 to his 63 using the original cross member and NO hammering on the tunnel. You'll need an adapter plate to mount the starter if you use the original engine.

[pfilean]

I put a 350 in my 61. Needed an adapter because of the starter problem and also my 350 was a Chevy bolt pattern. There are two nice adapters I know of maybe more. Although delivery maybe a problem as this is not a high demand piece and maybe not waiting on the shelf. It needed minimal hammering. For a 400 and no hammering I would want to look close at the resulting U-joint angle and maybe the clearance between the U-joint and the cross member. The 400 may require lowering the transmission and make the carb out of level and change the float setting. Maybe a change to fuel injection solves that. Not to mention distributor to fire wall clearance. There are a number of stories on this site about transmission swapping. Do some searches about replacing Old Jim and see what you think. I didn't want to change from a stock transmission but I really like the 350.

[Keith Seymore]

Originally Posted by rosconz

I got a slim jim(free) from a guy in Wellington as a spare for my 63 Cat, he fitted a TH400 to his 63 using the original cross member and NO hammering on the tunnel. You'll need an adapter plate to mount the starter if you use the original engine.

Agree.

I put a TH400 in my 63 GP and it's a tight fit. A TH350 should be no problem.

Also agree - a starter mount plate will be required if using a 63 engine, even with a BOP trans.

K

[RocktimusPryme]

My 62 has a (poorly) fitted olds 455 and longtail TH400. The 400 is at much more of an angle than I would like. Im assuming because someone didn't want to massage the floor. Which is funny considering the bad job they did with the engine mounts. But I agree the 350 should go pretty easy based on mine having a 400 stuffed into it with no hammering.

[455-4+1]

Thanks for the replies, the Slimmy Jimmy is out at the moment so I will see if I can pick up a TH350 locally, even just to try.
Realise the starter issue, sowill go with a plate.
I am going to do a new cross member anyway to give more clearance for 2.5" Exh and X pipe so will hopefully incorporate with that.
Cheers

[Goatracer1]

I have a T350 in my 1964 GP and it fits very well.

[455-4+1]

Yeah I think the GP has a bigger trans tunnel than the Cat.
I picked up a BOP TH350 locally to try, I only had to massage the tunnel a little using a round bar as a dolly, doubt it would even be noticeable form underside, and definitely not from the top.
The only clearance issue was the modulator (just) and the top 2x bolts / bosses that hold the tailshaft on at the rear.

Which got me to thinking.....

If that fits how far off is the TH400 ???

I put one up in place and it looks like its only the top 2x rear bolts for the tailhousing, about 1.5" back from where the TH350 was clearanced. Everything else looks fine.

It was just popped in place using a jack stand at this stage, but I will confirm if everything is OK once bolted in place. Will surely make the kick down provision easier with the Th400 than the 431x rods, cranks, brackets and levels with the Roto 10 setup LOl !!!!

[Keith Seymore]

Other way round: Cat has a bigger tunnel than GP.

K

[Goatracer1]

You are BOTH Wrong. The Cat and GP are the same car just different trim. The Bonneville and StarChief have the better transmission hence the bigger trans tunnel.

[455-4+1]

Originally Posted by Goatracer1

You are BOTH Wrong. The Cat and GP are the same car just different trim. The Bonneville and StarChief have the better transmission hence the bigger trans tunnel.

Yeah, I said "I think" LOL.

On mine (63 Cat) neither TH350 or TH400 would fit without some small modification to the tunnel. Looks like the TH400 will go, it just needs the tunnel massaged a bit further back than the TH350 needed. Its only a small amount, so will get onto it and post results (with pics)

[Yellow Banana]

Goat Racer is correct about tunnel sizes. I put a BOP TH 350 in my 64 GP. I was fortunate to find one with a lock up torque converter. There is a controller available to automatically lock and unlock the converter, but they were not available during COVID and I just utilize a lighted under dash switch to control it. Locking the converter on the highway is a nice option.

I did use a modified transmission mount