Q: I have a Mustang Foxbody that will get a 1970 460 big block.
So far, the engine has been bored .030 over, has TRW 10.5:1 forged pistons, ported and polished 1970 429 heads with 2.245/1.725 inch valves, and an Edelbrock Victor 460 intake port matched to the heads. The car has an 8.8-inch rear axle with 4.10 gears and a C-6 transmission with a TCI 3,500 rpm-stall converter with a B&M shift kit.
I want to know what size cam I should use. The Mustang will be a street/strip car, and I would like the engine to have a bit of a rough idle. Also, if I use an 850 cfm Holley double pumper, could I jet it so it acts like a 925 cfm carburetor? Is my rear axle gear too much?
A: We will recommend, not just a cam, but a cam with a matched set of lifters and valve springs.
This Crane PowerMax Cam and Lifter Kit features a hydraulic cam with 236/240 degrees of duration at .050, .556/.565 inches of lift, the lifters, and springs with retainers.
This is a good kit for a dual-purpose car like yours.
As for the carburetor, you can’t “jet it up” to a larger cfm. Jets don’t affect air and fuel flow, so all you would have is an 850 cfm car with jets that are way too big. The 850 will be fine for your 460. More gas will actually make you slower because the air/fuel mixture would be too rich.
Your rear axle gear is okay depending on tire size.
Ideally, you want your cruise rpm (at 60 mph) to be at or above the stall speed of the torque converter to prevent converter heat buildup. For example, using a 29-inch tall tire on your Mustang will produce a cruise rpm of 3,095 at 60 mph.
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