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 Holley 4180 four barrel 
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Joined: Fri Apr 10, 2015 6:59 pm
Posts: 1
:=D I have been following this site for a while, and finally registered. First, let me say this is a great site, and I have learned a lot just by reviewing the old posts. Lots of knowledge being shared here, and old myths debunked.

I have acquired a couple of swap meet 4180 Holley/Motorcraft 4 barrels, that had factory rebuild stickers on them. and are pretty clean As I have almost nothing investing in them, and enough gaskets & miscellaneous parts to rebuild them, I want to experiment a little bit. Everyone says "get a performance Holley", but I am time rich/money poor (or maybe just too cheap). I am familiar with Holley carbs and have rebuilt quite a few over the years, I want to figure out how the 4180 is different from the 4160, and see if it can be modified for more of a performance engine.

Here is the current set-up:

#E5HE-9516-EB
LIST - 50260-1, date code 3175.
As the base plate only has primary idle screws, I am guessing this is off a truck. (edit - off of a 1985 truck 460)

Primary metering block - 10647, 3
Secondary plate - #2

PRIMARY:
MJ ................................. #612
PV ................................. generic, will start with a 6.5"hg single stage
PVCR ............................. .0785"
IFR's ............................. .029"
IAB's ............................. inner - .082", outer - .025"
MAB's ............................ .043"
T-slot restrict................... .0935" (I have read this is actually a tube of some sort? It is pressed in the bottom of the main body)
Emulsion:
?? - tube type in main well, not removed
Kill ............................. .none

SECONDARY:
MJ (plate)...................... 00635
PV ................................. n/a
PVCR ............................. n/a
IAB's ............................. .042"
MAB's ............................ .0225"
IFR's ............................. .plate has a lower 0.025" and upper 0.029", in series. Anyone know the reason for this?

Emulsion:
n/a

Questions:
1) what is the purpose of two PIABs, with one outside the choke housing? All I can come up with is to lean out the mixture on initial startup when the choke is fully closed - is this correct?
2) The PIAB inside the choke housing is huge. Seems like this carb is calibrated very lean, with the primary main boosters starting very late. Would 0.070" be a good place to start?
3) Pri IFR - no change for now.
4) The primary booster (annular) feed passage in the booster is 0.166" but only 0.157" in the metering block. Is this a restriction?
5) The secondary booster (straight leg) passage is only 0.136". Should this be increased somewhat to be closer to the primary size?
6) The primary idle passage in the main body is only 0.0935", vs 0.120" in the metering block, and 0.120" for all the other primary and secondary passages. This seems like a built in TSR - should the diameter be increased?
7) At the baseplate mating surface, the main body primary idle passage has either an 0.0935" restriction, or a tube. Which is it, and what is the purpose?
8) PVCR - I am sure this is too large, and will convert to screw in type using brass screws.

Sorry for the long post, and thanks in advance for your advice and comments. Carb will eventuall be going on a SBF in an F150 or Ranchero.

James


Sat Apr 11, 2015 6:20 pm
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