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Old 11-27-2020, 08:15 PM   #1
chain drive
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Default 4100 carb

anyone ever run a 4100 carb on a flathead?
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Old 11-27-2020, 08:43 PM   #2
scicala
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Default Re: 4100 carb

I'm sure it would work well, but would need an adaptor to fit on the small 4 barrel pattern on flathead intakes. They were made in a few different sizes from about 400 to 600 CFM.

Sal
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Old 11-27-2020, 10:25 PM   #3
1948F-1Pickup
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Default Re: 4100 carb

Haven't run a 4100 on a flathead but you'd use a Navarro or Offy or other purpose built 4-bbl manifold.
From Autolite the 4100's range from around a 1" venturi to a 1.19....
a bit over 300 cfm to about 600 cfm at the other extreme. The SAE standard would be to flow automotive stuff at inches of mercury, Autolite may have done it at inches of water because the 4100 numbers aren't quite as impressive as Holley's.
Here's an experimental "blower" 4100 with 1.23 venturis-
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Old 11-28-2020, 11:55 AM   #4
rotorwrench
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Default Re: 4100 carb

When I had an old 64 T-bird, I had problems with the vacuum diaphragm that operated the secondary throttle plates. I ran the car mostly on the primaries due to that. I replaced that diaphragm multiple times and they just didn't want to last. Maybe I was too heavy on the throttle or the parts were just crap I don't know.
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Old 11-28-2020, 05:57 PM   #5
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Default Re: 4100 carb

You just needed one of these nifty vacuum secondary override kits.....
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Old 11-29-2020, 11:34 AM   #6
rotorwrench
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Default Re: 4100 carb

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Making it mechanical would certainly solve that problem.
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Old 11-29-2020, 11:53 AM   #7
scicala
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Default Re: 4100 carb

Quote:
Originally Posted by 1948F-1Pickup View Post
You just needed one of these nifty vacuum secondary override kits.....
Or fix the carburetor so it works as designed. Should be simple. The manual over ride secondaries is also a guaranteed hesitation/lag/backfire if you nail the throttle without a secondary squirter. That's a teenager trick.

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Old 11-29-2020, 12:06 PM   #8
1948F-1Pickup
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Default Re: 4100 carb

Has been working just fine since 1981, but then again I don't try to
open all 4 bores at 15 mph....
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Old 11-30-2020, 01:28 PM   #9
rotorwrench
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Default Re: 4100 carb

It would take some venturi vacuum to open the secondaries. It always takes a bit to get enough flow from the primaries to get the secondaries to open up. My problem wasn't that the diaphragm would be damaged by a back fire. It's that the way the diaphragm is made, it just has slots to clear the retainer screws that hold it in place. It eventually just pulls the diaphragm into the chamber. Holley's design for vacuum secondaries is better. I'd get on the old bird to pass someone but it was no drag racer off the line. I think a person would be better served by two 2100s with a progressive linkage or simply use a Holley 4V instead. Ford used the Holley for performance applications for a reason.

I don't think those Eelco kits are available anymore.

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