Reference Manual

Chapter 1: Engines: Oldsmobile V8s: 13-second 307 recipe


A low 13-second recipe would be a stock short block 307 with the following mods:

Be careful about wanting to use too much cam for a street 307. Especially with those sad 7A heads. No matter how long you hold those valves open, it's still sipping through a straw.

Since the computer only controls the primary side of the electronic carb, as well as the ignition advance, there's no reason to discard it. If the 307's intake manifold is being replaced with one with larger runners, you'd probably have to change the size of the jetting on the primary side. You might also want to use a non-computer carb on the car, and see if this makes a difference.

A high-stall converter is a good idea, but the real gains would come from swapping in some 5A heads with a Performer intake. No matter how much you open up the induction or exhaust system, with the small-port heads you're really being held back.

To realize any significant power gain, you'll have to open up the motor. Try a K&N filter, perhaps an aftermarket exhaust, and fine-tuning the secondaries on your carb.

The problem is not that the carb or exhaust is too small; the restrictions lie in the valve/port size, the lift and duration of the camshaft, and most significantly, the highway rear gears that keep your engine revving much lower than any speed at which you can take advantage of those modifications. (4)


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