Thread: How much lift can stock Vortec heads handle?

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Welcome to CHR!
The article referenced by Tech is really spot on. The stock Vortec is limited to .420 lift. You will find people that claim to have the stock heads with more lift but one of three things exists with a claim of a stock head running with greater than .420 lift; a) damage is being done (or has already been done) to the head, b) the measurement was done incorrectly (actually .420 or less) or most likely, c) the individual doesn’t really know what the net lift is. The most a stock Vortec head with stock components will safely accommodate is .420. Anything more requires machining the valve guide boss and the valve guide as well as new seals.

With proper machine work as outlined in the article, it is possible to have up to .600 lift on a Vortec head which is more than sufficient for all but the most radical valve train combinations. The pushrod holes should also be enlarged to 1/2" if you'll be using other than stock 1.5:1 rockers. As to the valve seals, see the pictures below.

Best of luck and let us know what you're building.

Again, welcome to CHR
Glenn