i have a 1971 340 engine. It skips at idle. how can i fix it?

Question

i have a 1971 340 engine. It skips at idle. I've put in new wires, plugs, cap, & converted it from points to electronic ignition. The motor has 30 over pistons, a mild cam, a carter abf competition carburator (4 barrel). It skips from idle to about 2000 rpms. If you hit the throttle hard there's no skip & the engine produces tons of power. I've done a compression test and have 135 lbs per cylinder. I've also replaced the intake gasket thinking I might have an internal leak, but it didn't cure the problem. Does anybody have any answers or suggestions? Thanks - Ross

Answer 1

By skips I assume you mean it does not stay at an idle. Check that the choke is operating correctly & all vacumm lines are secured. Check the carb low speed idle screws are set correctly. They are located on the front base of AFB carb. Clip a hand held tach on the coil. Turn each screw in one at time until you achieve the highest idle reading. If this doesn't help, check that the brake booster is working, depress the brake pedal, it should not be hard to push. If it is, then check your manifold vacuum. Should be 15 - 20 inches at an idle. If there is very low vacuum then the cam duration may be too much for your engine.

Good Luck. . .

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