392 Holley

C

Chip Nimmons

Member
I bought a nice used 4150 for my 392, its a 600 I think. When I rebuilt it I found plugs where the powervalves should have been. I replaced them with new power valves but I'm thinking that the jets have been modified. I want to replace them, what's a good starting size?
 
If you will post the list number stamped on the airhorn, I'll give you the original equipment data for that carb. Then we can determine exactly what carb you are dealing with and if it's suitable at all for that engine application.

The only time any similar carburetor would have the power valve(s) removed and the core plugged is when used in flat-out dragrace scenarios where the carb goes from an idle of say 2000rpm to wot instantly. I can't think of any situation that would be any worse regarding drivability than any carburetor having it's economizer (power valve) systems deactivated!
 
chip nimmons said:
r 4318 a
Click to expand...

The oem setup on that carb would be #53 jets in both ends.

The primary power valve would be a #65, the secondary power valve would be a #85.

If the list number is 4318a (ihc 379287 c91), then the carb is oem on a 1970 392

if the list is 4318-1a (ihc 443281 c91) it would be for a 1973 model application.
 
As previously mentioned, there is probably little inside that carb that is original.

A 562 jet is simply a "close limit" jet developed for emissions purposes. It's a 56 jet size that has been hand-calibrated and matched to more jets of the same flow rating and then "stamped" with the close tolerance digit.

For use of that carburetor on a 392 using e10 fuel, I'd run it #64 jets in the primary and #66 in the secondary.

I don't have the actual air flow rating for that carb, but I'd suggest it's a nominal 525cfm based upon it's throttle plate diameter.
 
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