[zeebo]

hi there..what would it take to install a 70+455 pontiac motor and th400 trans in a 63 catalina? special mounts/fabrication? i know i need a th400 yoke for the driveshaft, and it might need to be shortened. anyone do this swap? thanks

[Stuart]

The engine should bolt right in. There's a pictorial on installing the TH400 over on the full size Pontiac club website: http://www.fullsizepontiacs.com/fsptech.htm You may or may not have clearance issues in the transmission tunnel - some people have said they had no issues, others have had to massage the tunnel with a sledge hammer in some spots to get enough clearance.

[Engine-Ear]

What Stuart said (er, typed)...

[64catdroptop]

If you're installing it into a Bonneville or Star Chief, you should have no clearance issues with the trans. If you're installing in a Catalina or Grand Prix, the top bolts for the tail shaft will hit the trans tunnel, but nothing that a BFH (big...hammer) can't take care of.

Ron

[Blackcat]

I've installed many late model engines and transmissions in 63's over the years.
I've had a 455 HO in my Wagoon years back. Before that I had a 75 400 out of a Bonnie in it. The engine is a bolt in if you have all the mounts on the block. Late 75 engines didn't have them so take care when using later than 74 engines. On cats you will need to use a Precision Adjustment tool on the Trans Tunnel to make clearance for the Transmission if your using a TH 400 or 350 trans. Swapping a 4-speed is easier in certain ways. If your using the 65 up HO exhausts a Mini starter is needed for clearance. Drive shafts will need to be shortened or changed. I recommend taking careful measurements and having a new one made instead of cutting an old rusty one. In reality it costs about the same in the end.

[zeebo]

thanks blackcat..yeah, i know that certain year blocks post 70 have 5 mounting holes, so im glad to know its a bolt in swap. np on the precision adjustment tool..i have a few lying around.. will i have to do anything to the trans xmember/rear mount? prob moving the xmember back some, and a new driveshaft will be in order..no issues there. the rest ill guess.. shouldnt be too tough then.....

[64catdroptop]

Yes, you'll need to make an extention on the crossmember. I use 1/4" steel and it's about a 2" extention. I have the pattern and can send it to you if interested. PM me your address and I'll send you the pattern. That way when you get ready for the swap, you've got a good idea what you need to do.

Ron

[Blackcat]

You can do a couple of different things for a cross-member. Like stated by 64droptop you can weld an extension on the stock cross-member and slide it back and drill a couple of holes to bolt down the clamps. I can't remember the year but you can also find a later cross-member and weld tabs on the ends and use it to attach to the trans. The advantage is the humps for the exhaust that the early cross-member is lacking. I believe one from a 73-4 full size should work.