Thread: Getting more power out of a 307

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Originally Posted by gte436e

I am also building on a 307, what aluminum head would work best??

Depends on what duty you have planned for the motor. A rule of thumb for a street/strip motor is to use heads with intake runner size at 1/2 cubic inches. 307 cubic inches X 1/2 equals choosing a runner size of 153.5 cc's. Moving up to the first commercially available aluminum cylinder head, if I were tasked with choosing heads for you, I'd choose the Edelbrock #60879 fully assembled units. These heads have the early manifold bolt pattern so you can use any of the standard early Gen I manifolds, although you'll have to use centerbolt valve covers. The small 165cc intake runners and 60cc chambers will be an excellent match for a "stroked 283" motor such as the 307. Springs are rated for max valve lift of 0.575", so you can run just about any cam you want to with them, within reason.

Cutting the block decks for 9.000" block deck height, using an Edelbrock #7310 head gasket and flat top pistons with a 1.675" compression height will put the static compression ratio at 9.74:1 and the squish at 0.038". I'd choose a cam with duration around 225-230 degrees at 0.050" tappet lift and use a 2800-3000 stall converter.

If you want, I'll put all the info into my DynoSim and choose a cam that will be tailored to your application. You may have to change the rear gear though, you can't run this compression ratio and a bigger cam using a stock 2.73 rear gear (for instance).

If I were not going to go to the trouble of building the motor and just wanted some aluminum heads on it, I might choose an Edelbrock with a larger chamber (64cc's), even though the runners would be larger and port velocity would be down some over the 60879 heads.