Can I use double hump heads on a 400 sbc?

Yes, If you drill them for 400 steam holes.

Sure, you can drill the steam holes and it will run. If you want them to last you'll need to have hard seats installed and chrome stem or better valves for them to last with unleaded gas. It's a safe bet that they'll need new guides unless they've just been done. Throw in magnafluxing, tanking and surfacing and the by the time you've paid the machine shop you could have bought a set of Dart or World Products heads that are ready to go on unleaded and much less likely to crack.

Good advice from tresi.

Another thing to think about is compression. A lot of the double-hump heads with the 1.94" intake valves have chambers with 60cc volume or less. Makes for a LOT of compression with a flat-top pisotn. Make sure your combination figures in the chamber and have the heads cc'd to be sure.

tom

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Ya cain't fix stoopid, but ya kin TAX it!

I always recommend aftermarket heads. It is not cost effective to run stockers. If you are going to use a stock head, go for the Vortec heads. You will need a Vortec style intake to match, but at least that combo would be worth it a little.