Quote:
Originally Posted by 'ol Pinion head
To get the OP's topic back on track, his 78 T/A's 400 engine is the base 400 engine, that means 6X-8 heads & memory serves right the beveled top 400 pistons which also lower static CR. Not the same as a W72 engine.
Back to his asking about a camshaft change, the only camshaft change that will have any benefit with that bone stock YU 400 longblock is one that increases cyl pressure. Im not a fan of the Comp XE line of cams & have no use for them in higher compression builds, but at 7.6-1 compression a smaller Comp XE with its increased ramp speed & fuel charge cyl filling are about it.
Desiring to have the bottom end professionally rebuilt with an over bore & forged pistons, swapping heads to a pair of done up 6X-4's one couldnt go wrong milling them .030-.035 & zero decking the block. Sourcing '70 & earlier D-port big valve 400 heads just to raise C/R will mean going with a much larger cam. Swapping to those "performance" heads will bring up not only the missing accessory bolt hole issue for the long alternator bolt (issue I've solved a few times), but also the Need for a gear swap in the rear, as well as convertor swap for best performance. Is all of this expense what the OP originally asked about???
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OP stated in the 1st post his engine already has 6x-4 heads...