Autolite 4100 Info

earl3820

New Member
Dec 22, 2008
2
0
0
Just a quick note for those wanting to install an Autolite 4100. I recently removed a Holley 4160 in favor of an accurate 4100 I re-built. Had numerous problems trying to tune and adjust. The idle mixture screws had to be 4 turns out to idle properly when warmed up. Could not keep running when choke was on and cold.

I am using it on a 289 with a factory Ford dual plane manifold and a 1" spacer. After numerous tries I finally discovered that every gasket sold by two Mustang suppliers and other auto parts stores were not sized properly. It appears that the individual bore holes are not correct in any gasket purchased.

Finally, cut my own gaskets using the spacer as a template. Did not change anything with the carb and now she works perfectly at two turns out on the mixture screws.

I wanted to share this since I see a number of articles about trouble with 4100 carbs when purchased from Pony Carbs or at swap meets. I would strongly suggest making your own gaskets to eliminate any potential for vacuum leaks.
 
  • Sponsors(?)


bnickel

Founding Member
Aug 21, 2002
5,640
1
77
51
lubbock, texas
Visit site
good info to have. fortunately i find myself in posession of 4 or 5 VERY OLD (asin pre 70) 4100 kits or just gasket sets. please do not ask me how much these kits cost though. i wouldn't even begin to answer if you did....LOL. let's just say my wallet hates me, my wife WOULD hate if she knew how much i spent on each kit BUT my credit card company loves me, at least as long as i continue to pay the minimum monthly payment anyway.
 

Kman

Founding Member
Nov 29, 2000
620
0
17
Connecticut
Visit site
The gasket from Pony Carbs works fine. Had the 4100 for my HiPo rebuilt by them last year and the gasket included is correct. They also sell the gasket individually.
 

l1k2gadd

New Member
Oct 27, 2007
53
0
0
Summerfield, Florida
Every gasket I have purchased from Napa for my carburetors has worked fine (so far), rebuild kits included, but I don't have any 4V cars, just 289-2V cars and 170 and 200 6 Cylinder cars. I have a "J"-Code '68 Cougar XR-7 but the engine is a later model 5.0 with a 2V setup I grabbed off of a 70 to 72 F100 because it had an aftermarket 4V setup on it too that was junk. I have a parts pickup with an older 352-4V that I have yet to get running again because it has a P.O.C. Holley 4V on it. I hope to find an Autolite 4V carb some day to put on it. I will know more about Napa's 4V gaskets when that time comes.
 

Edster

Founding Member
Aug 13, 2000
500
1
19
League City, Texas
Due to an article in one the mustang mags larely supported by Pony carbs the 4100 has become highly desirable. This my be because once set up right you can forget about as it seems to hold its tune. I'm not really sure why its desirable its just my guess. The point is that this desirability has driven the price up on these once thrown away carbs.
 

bnickel

Founding Member
Aug 21, 2002
5,640
1
77
51
lubbock, texas
Visit site
Due to an article in one the mustang mags larely supported by Pony carbs the 4100 has become highly desirable. This my be because once set up right you can forget about as it seems to hold its tune. I'm not really sure why its desirable its just my guess. The point is that this desirability has driven the price up on these once thrown away carbs.


i used to run 4100 carbs almost exclusively on my stock engines but i ran into a problem with a couple of them where i broke off the mounting ears either due to warped carbs or a warped intake spacer, never figured out which because i bought a brand new 600 holley instead, i always wished i had just bought another 4100 instead. later i started building less stock engines and started using carter AFB carbs and Demon carbs instead.

when i start working on the 69 cougar i'm going to swap on a ford muscle parts c90x aluminum intake and tricked out 4100 carb. i found an old article from the 70's about how to super tune a 4100 so i'll build the carb to those specs and i also plan on epoxying the underside of the mounting ears on the carb to hopefully prevent any more broken ears as well. i'm also going to experiment with opening up the throttle bores on the carb a bit as well to increase the CFM some which will be kind of tricky since the throttle bores are barrel shaped but i'll make it work
 

Edster

Founding Member
Aug 13, 2000
500
1
19
League City, Texas
i'm also going to experiment with opening up the throttle bores on the carb a bit as well to increase the CFM some which will be kind of tricky since the throttle bores are barrel shaped but i'll make it work

Its amazing how much CFM you get from a few millimeters (yeah I know its metric but its easier for my hard head to figure out). I used to ream out venturis on Rochester 2jet carbs for my VW bug, it was way cheaper than Webers and worked almost as good.

All in all I wouldn't mind using a 4100 if they were still cheap.
 

bnickel

Founding Member
Aug 21, 2002
5,640
1
77
51
lubbock, texas
Visit site
Its amazing how much CFM you get from a few millimeters (yeah I know its metric but its easier for my hard head to figure out). I used to ream out venturis on Rochester 2jet carbs for my VW bug, it was way cheaper than Webers and worked almost as good.

All in all I wouldn't mind using a 4100 if they were still cheap.


i haven't paid more than 40 bucks for the ones i've bought recently off of ebay, hell i paid more for the kits than i did for the carbs themselves.
 

johndean66

New Member
Jul 6, 2005
3
0
0
I rebuilt my 4100 3 years ago and two turns out and she runs great. Had a float go bad last year, but that's a quick change. I like the carb. I have a 1.08 and due to rebuilding my Mexican 302 and going with performance heads and magnum cam, I will be looking for a 1.12 to rebuild.

John