[Paul Chapman]

I have a 78 400,I am shooting for 350 to 400 horsepower,the block is .030 over,6x heads,and forged flat tops.This is my first Pontiac motor (usually chevys),I was wondering if anyone knows if the stock rods with arp bolts will be strong enough,and if 6x heads are ok,or go for a set of Edelbrocks

[Paul Chapman]

I have a 78 400,I am shooting for 350 to 400 horsepower,the block is .030 over,6x heads,and forged flat tops.This is my first Pontiac motor (usually chevys),I was wondering if anyone knows if the stock rods with arp bolts will be strong enough,and if 6x heads are ok,or go for a set of Edelbrocks

[Mr Dave]

For that power level, stock rods should be fine. Personally, I prefer the older high compression heads to the 6X. But the money spent on Edelbrocks for a 350-400 HP engine could be better spent on the rest of the car.

[Will]

There are two varieties of 6X heads. The 6X-4, and 6X-8. The 6X-4 are the only ones you'll be able to get any compression out of, and then you'll have to mill them considerably. If you mill the heads .060" on the block and intake sides, and you zero-deck your block, you'll end up with right about 9.2 - 9.3:1 compression. A little less milling on the heads (say .040") will put you at 9:1. Possible to achieve your performance goals with that compression ratio and still run on cheap gas.

See this website for information on identifying which 6X head flavor you have: http://members.tripod.com/futom/id59.htm

Be sure to have your rods resized when you put the ARP bolts in. Having them shot-peened is a good safety measure also.

Good luck!

[SCOTT ESTERLE]

I've used stock rods for years with ARP BOLTS & have them re-sized. I run a 406 & shift at 6500 to 6800 the car runs anywhere from 11.60's to 12 teens. I also use the Trw slugs. My compression is around 9.75 to 1.