Big,
That would be me.
I am putting a 472 Cadillac and THM-400 into my '65 Tempest Wagon.
The car is being built as a drag racer; S&W back-half, Dana 60, full roll cage.
The big Cadillac presents several problems for a swap into a '65 Tempest. It is not a big block Chevy (BBC), shares nothing with it. The Cadillac distributor is in front, leaning over on the drivers side. Think mirror image of a big block Mopar, external oil pump and all.
Three major issues to deal with:
1) Motor mounts. As mentioned above, you will need to weld horns to the front of the crossmember to put the mounts out where the Cadillac has them, at the very front of the block.
2) The bore spacing is 5.0 inches on the Cadillac (the only thing stock on a Pro Stock motor is the bore spacing and it is a Cadillac number, not Chevy). That means the headers do not bolt up. I have heard on people bending the tubes to fit, but realistically you will have to cut the headers up and reweld them. 3-D spacial geometry comes in handy.
3) The cylinder banks are offset opposite of the BBC, meaning that the passenger side is slightly ahead of the drivers side. This messes up the header build-up two ways. The passenger header downpipes have to be run way aft before they can go down and they go down right at the starter. An aftermarket geared starter is a must. The second thing is the suspension. Upper A-arms, the pivots, and the pivot mounting bolts are all in the way of the first two pipes. Major tweaking is required here to get everything packaged with clearance.
Definitely doable, but not a weekend project. I spent seven months of weekends building header flanges (you are better offer buying flanges from one of the cadillac forum vendors), cutting off the collectors and repiping the headers for my car.
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JB 472
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