Thread: What Jet size to use on 4bbl Holley on OHC-6 Chevy 250?

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Any Ideas.....



Im rebuilding a second hand Holley 4bbl 600cfm, its gona be placed on a Chevy 250 OHC-6, Exhaust heated manifold, only really want to use it for fast street, but not really sure on what jet size to use??????



Many thanks in advance

trial & error is all I can say..I would think a smaller carb would work better however

A good starting point might be 65 on the primarys and 68 on the secondaries and go from there either up or down as needed.
I agree the 600 seems a little large for that size engine, unless you plan on really turning up some RPM's on it.

Taz; Is that Colchester England? I'm tuning a '55 Chevy with a 235, and I was advised that a Holley 390, or a Weber 38dgas were the best options. Went for a 390 on a Clifford manifold [which I'm still waiting for] Loads of stright six tuning stuff for your engine on American ebay.
Col