408 Build

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Apr 15, 2026 | 08:53 AM

Carp

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408 Build

Sent my 6.0 LY6 short block to the machine shop for a basic rebuild and they said it’s .003 too far out of round. I then decided to pick up a 408 Stroker kit from Jegs for 2k. 4032 pistons and scat crank and rods. Only issue is the 706 heads I planed on using on the 6.0 is a no go as compression would be around 12.5. With 243 in at 12:1 but with 823 or 317 heads I’ll be around 11-11.3.

This is going into a 96 C1500 for a cruiser and don’t plan on racing it so sticking with a smaller cam. But before I spec the cam I have to make a decision on the heads.

Will stock 317 heads perform bad if I plan to stay under 6500? Currently have new set of PAC 1219 springs. I also looked at the AFR 238 LS3 heads but not sure I want to put down that much on them as they aren’t much better than factory.

Anyone have a similar build they can share advice on?
Will run a 4l80 3200 stall and 3.42 gears for now.

Apr 17, 2026 | 12:21 AM

KCFormula

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317's are the same port as a 243 just larger CC. I wouldn't hesitate to run them. But more ci = more $$. So if you want large HP gain you will need to bump to a LS3 or even LS7 head.