I'm curious about an apparent inconsistency in the size stamped onto the Holley main jets that came out of a Holley two-barrel 6280 feedback carb designed for the Chrysler 3.9L engine that went into the 1987 Dakota V6.
The jet is stamped "175", but the hole appears slightly less than 1 mm in diameter so the 175 cannot be in reference to the hole size, which would normally indicate a 1.75 mm opening.
Could this be in reference to flow rate that was used by the 124-XXX series of Holley main jets? I couldn't find anything that referred to a Holley 124-175 main jet anywhere on the web and Holley wants an incredible amount of info before they will accept an email inquiry. The following site has a table of equivalence between the 124-XXX jets that are flow rated and the older 22R-103-XXX that are size rated.
"Note that not all available jets may be listed as they might not flow an equivalent volume between old and new jets."
A flow rate of 175 cc per minute seems low but these main jets were augmented by the jet that was controlled by the mixture control solenoid, so maybe the 175 *does* refer to flow rate.
Anyone know for sure? Holley website was no help. The Holley Tech Service Request Form was like a final exam and I guess was put up to deter people like me looking for info on arcane, abandoned technology.
Jack