Holley 4180 Observations, Tidbits, & A Vacuum Secondary Tip

[Walking-Tall]

Finally got an opportunity to rebuild a ('84) Fox Mustang 4180 Holley 4 barrel. The Mustang it came off of now has a 460 in it, and no, this carburetor is not going back on that car, but another on the 302 that came out of it. He's got a 750 I built on the 460.



Observations and tidbits, pretty much in the order of execution:
1. Owner provided a (unopened) NAPA rebuild kit. All the parts'n'pieces. No air cleaner gasket. Unfriendly black gaskets.
2. Ford liked wicked adhesive and gaskets, and to pinch-peen the accelerator pump shooter and screw. (neither is necessary)
3. Nearly took an axe to remove the primary metering block and secondary metering plate. (small flat screw driver, hammer)
4. I'd yet to meet remnant gasket material and adhesive that stood a chance against the carb cleaner. Now I have.
5. Count on ample time for manual gasket material and adhesive removal.
6. The correct stem length vacuum secondary diaphragm is within the NAPA kit. (kit part # 2-5363A)
7. Kit came with new needles and seats, but also nice new adjusting nuts and lock screws.
8. Primary anti-tamper idle mixture screw plugs already knocked out.
9. Removed secondary anti-tamper idle mixture screw plugs. Details not pretty, but effective. Don't even think about drilling these unless you've got carbide tipped drill bits or the equivalent, because these thick hardened plugs will laugh out loud at anything less for drill bits.
10. Mixture screw settings, including the ones Ford buried out back, uneven/all over the place...

11. The secondary transition slots are quite long. Set secondary idle screw to 1/4 turn from fully closed, for no sticking in the bores at idle and for zero secondary transfer slot exposure. Set secondary idle mixture screws to 1/2 turn out (3/32" allen wrench), approximating the 0.025" secondary constant idle feeds in most Holleys.




12. Drilled and tapped for a customary primary idle speed screw location, eliminating idle solenoid from the already crowded area.




13. Primary idle mixture screws set to 2 turns out. All of them to be final adjusted on the warmed up idling vehicle (3/32" allen wrench) .
14. Set the primary idle speed screw for approximate square exposure of the primary transition slots.




16. Reassembled the rest of it like any other, with a light layer of "chap stick" on the gaskets in the absence of non-stick gaskets.


A tip on how I install vacuum secondary diaphragms for no tears or mishaps:

Upturn the diaphragm as shown (which positions it's passage and voids accurately onto the housing), set it into/onto the housing, clamp the stem from below so the housing bottom sits on the vice grips (I don't presently have one, but a bench vise works nice for doing this) and the stem stays put. This accurately aligns the screw holes for lid and spring installation without movement/distortion of the diaphragm by the pressure of the opening rate lid spring as the lid is pressed down to install it. Don't forget the check ball if it requires one. Lightly oil the four screws' threads so they don't catch/tear the diaphragm. Set the lid (with it's opening rate spring) on top, slowly/lightly lower it, aligning diaphragm and lid with the screw holes, install the screws.







Test the unit and your diaphragm installation by holding it upside-down, compress the stem in, hold a thumb over the vacuum passage to block it, release your hold on the stem and verify that the stem stays put. If so, she's good to go.