[Tom Vaught]

Been a while since I posted on the Holley Carb Sticky.

I was looking at some Hot Rod Magazines I plan to donate to a retired Holley Guy I worked with back in the 1970s. He is putting together a "Library" of information that was printed in all of the old paper magazines, like Car Craft, Popular Hot-Rodding, Hot Rod, etc. I have donated to him about 6 thousand magazines so far. Still have a lot to deliver to him at a later time.

So I ran across a Hot Rod Magazine dated Hot Rod 2013 JULY and I will talk about an article called "The Holley 6 Pack Carbs, on Jim Mooneyhan's '70 Dodge Coronet, 440 are messed up. We are going to fix them.

So without typing the entire article, I will post the Issues that Mr Mooneyhan has with his 6-Pack set-up:

1) The car (engine) idles too fast.
2) The Throttle Response is bad.
3) There is a lean surge at 55 mph.
4) The engine seems rich at idle.
5) Turning the Idle Mixture Screws or Idle Speed (Throttle Blade) Screw has no effect.

Info: The End Carbs are original 440 6 Pack carbs. The Center Carb, He said, was correct for a 440 Six Pack set-up with auto trans. This info is from Marlin Davis, a Hot Rod writer. So they took the car to "Joe's Garage", a shop in California apparently.

It was delivered on a trailer to the shop and when attempting to get it off the trailer it had a 4000-5000 rpm "idle".

Initial Diagnosis showed the following issues, as received:

a) A bent "Divorced Choke" linkage. Choke was not completely allowing Curb Idle speeds.

b) Center Carb had a "Blown Power Valve" Normally this would not be an issue at idle but at 4000 - 5000 engine rpm would be adding fuel to the engine increasing the speed.

c) Center Carbs intake manifold gasket was damaged (leaking), allowing increased idle air into the intake.

d) Center Carb had 90 main jets on the center carb (normally used on only the rear of 4 BBL carbs unless you are racing a Dominator Carb). 6 Pack rear carbs use Metering Plates vs Metering Blocks.

e) A 50cc Accelerator Pump was installed on the Center Carb. In some cases on 850 cfm #4781 carbs for racing this mod works with the large cfm primary barrels. NOT on a small center carb on a 6 Pack set-up (which was later identified as a 340 6 Pack carb, not a 440 center 6 Pack carb).

f) "An Idle Air Bleed on a "end carb" was blocked".
Just for information for the guy who was given the info about the carbs, THE INNER AIR BLEEDS ARE THE HIGH SPEED AIR BLEEDS. THE IDLE AIR BLEEDS ARE THE ONES CLOSEST TO THE OUTSIDE OF THE AIR HORN RING. The blocked air bleed was a high speed air bleed.

g) The End Carbs had "sticky" throttle blades. Not opening and closing smoothly most likely caused by the other issues and a lack of maint by the owner.

h) Two bad plug wires and fouled spark plugs.

i) Idle vacuum at best was 5" of idle vacuum but the engine was pumped and found to be solid internally.

Fixes: Basically fixed all of the issues mentioned above, converted the Holley center carb to a 440 center carb calibration. Not sure what the Holley people told them to do vs just replacing the carb with a proper 1970 Holley 440 center carb which Summit/Holley was selling at the time. I would have put the right center carb on the vehicle immediately. Today 2021 that may not be as easy to do, back then they were available.

(I fixed a Ford Guys Holley Tri-Power Set-up one time (for free) after the guy had a shop Powder Coat the carbs vs (have them dipped properly) and "unplugged" most of the air bleeds in those carbs, along with putting the right calibration in the carbs.)

SO THE POINT OF THIS IS, TAKE YOUR HOLLEY CARBS TO A SHOP THAT ACTUALLY KNOWS HOW TO WORK ON THEM PROPERLY. Especially if they are rare set-ups.

Tom V.