Quote:
Originally Posted by Ponchomike57
So I’ve decided to hold off on building a 461 for my 57 chieftain and decide to build a nice street 400 for her. I’m saving the stroker for my next project (66 GTO)
I’m looking to build a 375-400 hp 450lbs torque 400. I’ve spect out a cam with Butler performance but haven’t figured out what pistons to go with yet because I have 2 different sets of heads to choose from.
I have a set of 1977 6X4 heads and a set of 1968 #62 heads. The 6X4 heads have 1.77 exhaust valves in it already, and the #62 still need hardened seats. I’m wanting to hit between 9.0-9.5 compression ratio. Which head is it easier to do that with, and which heads flow better?
Thanks for your opinions!
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We’ve built several 400’s that are primarily for the street, but able to compete legally in the pure stock drags. The 3 that are shown are similar build-wise with forged rotating assemblies for safety, stock heads, mild HFT cams, and exhaust manifolds (both log & RA). As Steve25 suggested, the 6x4 and 62 heads flow equally (with a slight nod to the 6x4’s) and will achieve 375 hp/450 lb-ft torque easily. My choice would be for the 6x4’s to achieve a safe low to mid-9 static compression ratio as Steve calculated. A cam, like the Summit 2801, is a good choice for good torque and power for your relatively heavy ’57 Chieftain. You can see in the comparison that the cams were different specs, but fairly mild, the compression ration varied from 8.75 to 9.95, with log and RA exhaust manifolds; the power output between the three was very close. If you go with the 62 heads, I’d run a cam like the Summit 2802 to lower the cylinder pressure and dynamic compression a bit.
Dennis