|
|
|
Supreme Being
Group:
Last Login: Friday, July 24, 2009 7:25 AM
Posts: 158,
Visits: 1,076
|
|
| I just acquired a Holley 490cfm model 4160 and want to try it on my '55 272 with B intake manifold, ECZ-G heads, 1.54 rockers, late distributor and dual exhaust. Can anyone recommend ballpark primary and secondary jetting and power valve value? Thanks
BrodieSavannah, GA
|
|
|
|
|
Supreme Being
Group:
Last Login: Friday, July 24, 2009 7:25 AM
Posts: 158,
Visits: 1,076
|
|
| Correction... it's a 450cfm (list 4548-S; DOPF9510U)
BrodieSavannah, GA
|
|
|
|
|
Forum Member
Group: Forum Members
Last Login: Thursday, October 01, 2009 9:38 PM
Posts: 41,
Visits: 321
|
|
| The stock factory (Holley, that is) primary jetting is 57s which is probably as good a place to start as any; maybe a little fat. If the cam is stock, a 8.5 valve or, better, 10.5 would be a good place to start. There are dual-level valves still available with even higher openings but they are pricey. Some 390/450 4160-style carbs didn't even come with primary power valves from Holley, though they can be installed. The secondary side should have a metering plate, which I'd leave alone for the moment, until you sort everything else out first. There are only a few plates available from Holley now, & if you need to go up, most people drill the existing plate one drill size at a time, to be honest. My $.02.
|
|
|
|
|
Supreme Being
Group:
Last Login: Friday, July 24, 2009 7:25 AM
Posts: 158,
Visits: 1,076
|
|
| Thanks for the reply Homey. The carb indeed has a power valve and 57 primary jets. According to my 55 shop manual, 292's with 4bbls. and auto trans were jetted with 52's on the primary side, so me thinks I will need to lean this Holley out before installing. According to info on the Holley website, this carb didn't have a power valve, but I sure removed one. I have the 37-119 renew kit and it comes with a 8.5 valve, so that's what's going back in for now. I'll post an update in about a week...parts are soaking in carb cleaner now!
BrodieSavannah, GA
|
|
|
|
|
Supreme Being
Group: Moderators
Last Login: Yesterday @ 2:44 PM
Posts: 2,557,
Visits: 6,860
|
|
| Brodie: I'm not sure I'd go to the 52 jets. The '55 four barrels were teapots, with smaller primary venturi than the the 4160. Bigger the venturi, bigger the jets. Just remember, carburetors measure air flow through them and supply the proportionate amount of fuel. They have no idea what engine is under them with what components. All they know is throttle position and air flow. Stock jets are always a good place to start, and tweak slightly from there. John
John - "The Hoosier Hurricane"
|
|
|
|
|
Forum Member
Group: Forum Members
Last Login: Thursday, October 01, 2009 9:38 PM
Posts: 41,
Visits: 321
|
|
My philosophy on carb initial jetting is pretty conservative. You can't really hurt an engine by being a little too rich, at least in the short term. (Note that the operative phrase there is "a little too rich", not "rich to the point of having fuel wash or hydro-lock.")  You can, however, have all sorts of interesting problems by being too lean. 57s are probably a touch fat, as I mentioned, but it makes a good starting point which won't hurt anything while you sort it all out. Might also think about installing a PV blowout protection kit while yer at it- I don't think that model originally had one from Holley, could be wrong though.
|
|
|
|
|
Co-Administrator
Group: Administrators
Last Login: Friday, February 03, 2012 5:43 PM
Posts: 3,130,
Visits: 2,148
|
|
| I'll add that the Holley and Ford numbering system on the jets also differed throughout the years which means the jets may physically fit, but the numbering between the two brands do not parallel each other. As John said, the original jetting for the carb being used provides a good baseline from where to start from. Even on carbs of the same size but have different list or part numbers, it's not unusual to have original jet sizes that are different and that's typically where air bleeds and emulsion tubes are varied within the carbs themselves creating a different feed requirement. You may find certain 600 cfm Holleys coming equipped with #62 primary jets while others come with #66 primary jets. The 4548 carb by my book is 450 cfm and came stock with 57 primary jetting. and is actually listed as being for automatic transmission equipped Ford vehicles. The rear jet plate should be a number 30 while the stock power valve for that carb was an 85 (8½ in/Hg or lower causing it to open). The #30 rear jet plate incorporates a 0.064" main feed hole while the idle feed restriction is 0.029". The 0.064" feed hole actually equates back to a #64 Holley jet size in this case.
  Lorena, Texas (South of Waco)
|
|
|
|
|
Supreme Being
Group:
Last Login: Friday, July 24, 2009 7:25 AM
Posts: 158,
Visits: 1,076
|
|
Thanks for everyone's replies. Ted, you're on the money with the info on what's in the carb now. I have purchased a set of 53 and 55 jets to play with and will post results. Right now, I have to locate my clutch head screw drivers left over from my old scrub truck days in order to finish dismantling the Holley.
BrodieSavannah, GA
|
|
|
|