I'm replacing the carter 1bbl, with a motorcraft 2150 2bbl...this is going on my 300 I6. what is a good jet size? which power valve would be good? 10.5 in. Hg, 2.5 in. Hg, 3.5 in. Hg, 4.5 in. Hg, 5.5 in. Hg, 6.5 in. Hg, 8.5 in. Hg ...I'm doing the rocker arm swap, and exhaust work
jet size #49, if the carb is a 1.08(venturis) stamp. This should be the jet size in a later 70's 302 truck. Is your intake aftermarket, or are ya using a 1-2 adapter? just the chev rockers? efi mani's, or 1 pc. header? As for a power valve, I can only guess putting a vacuum gauge on the manifold and measuring at various steady cruise speeds, and picking one that measure 2" hg below that. Stockl or slightly modded engines typically have 65, 75, or 85 (6.5 in hg, 7.5 in hg, 8.5 in hg) My 2 cents.
I guess I do this with a old 302 2100 2bbl carb this summer, with an homemade adaptor, if the setup will not too height, cauz My truck is a Van, and with the 1bbl I have already enough space.
My 300 is not modified, 300k original, but I want to try this just for fun to see what changes on running/gas mileage...
What do You think???.
Have a nice Day,
Dom.