Thread: Chevy 350 rebuilding tips

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If the light springs are enough to close the valves at your target rpm, you will have no deficet in power.

Since you've got the engine assembled, now you need to focus on the things on the outside, like spark plugs. Don't worry about running any fancy platinum plugs or anything. Try and get a stock type non-resistor plug. File back the tip until it covers only half of the center electrode, and then round the corners off. Open up the gaps on the plugs until the engine starts to misfire under full power close them up a little. Stock gaps are too conservative. If you open them up too far, though, t's harder to light a cylinder under higher pressure and pressures increase as you open the throttle so you may be ok with a big gap at idle but it will hurt you under power.

Find yourself a vacuum guage. In order to hold a certain rpm, you have to open the butterflies on the carburetor to a certain opening. The more you open the butterflies, the less vacuum you make. So, if you increase the efficiency of the engine, you don't have to open the butterflies as much to make the power required to run a certain rpm and you'll pull more vacuum at that rpm. Tune the engine to make as much vacuum as possible under light load at the rpm near where you expect peak power to be.