stock 403 w/ #7 heads

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October 1st, 2018, 08:14 AM

Via3d

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stock 403 w/ #7 heads

IF I have a stock 403 and if I put stock #7 heads on the 403, how much horsepower / torque gain is reasonably and roughly expected ? (compression bump?)

All else stock except dual 2.5" exhaust. Qjet is 800cfm.

October 2nd, 2018, 06:14 AM

AZ520

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25 horsper

October 2nd, 2018, 06:17 AM

oddball

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Some? Maybe in the 30-40 range? The stock cam isn't exactly anything to write home about, so it'd definitely be best to do a cam swap while you're in there.

October 2nd, 2018, 09:28 AM

brownbomber77

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Better off cutting .030 off it unless you're using one of Smitty's .011 head gaskets. Otherwise, it's a bit of a lost cause because you're adding .030 of gasket material.