Gentlemen I am using a Holley 1850 450 CFM on a 90 H.O. roller block with a Ford manifold and stock cam. Any suggestions on initial jetting and power valve no.? The vehicle is used mainly at a 600 ft. altitude. Thanx John
List 1850 is a Model 4160 600 cfm Holley 4V...it has jets in the primary metering block and a metering plate with non-modifiable orifices on the secondary side.
The primary jets should be a 65 to start...testing at WOT and reading the spark plugs afterwards will indicate if leaner or richer jetting is necessary. Stock accelerator pump squirter should be .025". If some lean stumble off-idle is noted, after verifying proper pump arm adjustment, a .028" squirter can be installed.
View this Holley Page as your gateway to general technical information.