Need help swapping in TH400

[CMars45000]

I have a 1970 4x4 K5 that had a BBC 454 in it that was kinda shoe-horned in. The th350 that was behind it is dead. I am putting in a th400 to replace the th350. Now, is there a simple, straight-forward method of accommodating the extra length of the th400 while providing some extra clearance for the valve covers that are oh-so close to the firewall in the current condition?

Will the factory big block motor mounts from the 72s move the motor forward enough to compensate fot eh longer th400? Will the factory BBC mounts help at all with the valve cover clearance issue??


We were considering moving the factory cross member forward 3-1/4" to help with VC clearance and compensate for the extra length of the th400. Has anybody attempted this??


Thanks for the help

[turp mcspray]

I put a 454/th400 in my 72 4x4 blazer. I moved the trans/transfercase mount rearward 1 inch. this put the transfercase shift lever back in the stock location. I also moved the engine crossmember forward the other 2" or 2 1/4". This gave me plenty of room for an hei. If you want to run tall valve covers you may need to "massage " the firewall. I ran a 2wd bb fan shroud, and everything looks like it was installed by the general himself. There is only one v8 frame mount crossmember, since no 4wd ever came with a bb.

[CMars45000]

After it was all said and done, how much room did you end up having between the fan and the radiator?

[turp mcspray]

I have it tore apart to paint at the moment. From looking at pictures, my best guess is in the 4" ballpark. My clutchfan fit half in, and half out, of a 2wd bb shroud.