Patience with Autolite 4300 growing thin

JC Mustang

Founding Member
Nov 1, 2000
Layton, UT
Finally got my new fuel sending unit squared away and could put on the "new" 4300 my buddy gave me. Once the fuel bowl finally got some gas in it, the engine fired up instantly with the classic one pump start. However, it quickly dies unless the gas is further pumped. After a while of working with it, I noticed that it has the (also classic) leak at the front of the fuel bowl. Since there is at least one stripped screw on this carb, I am becoming reluctant to bother rebuilding it, as I may just find it to be too much trouble.

I am considering ditching this carb and getting a 4100, my familiarity with the 2100 and the general good praise I have heard of the 4100 (and the denigration of the 4300) being the key factors. I am not concerned with "code correctness" (indeed there was no 4100 for 1968 Mustangs), but I do want a carb that actually works. In the picture of the bottom of the throttle body here, there seems to be a little vacuum fitting at the "front" of the carb below the thermostat housing. Is this for distributor vacuum advance? Do all the 4100s have vacuum advance? I need it. Also, are the 4100s from the Thunderbirds, Galaxies and such interchangeable here, at least functionality wise? I notice that the choke hot air fitting is pointing a different way on the Thunderbird pics at

I am reluctant to "lose" all the carb info in my 68 shop manual, would I set up my carb to specs in, say, the '66 manual? Any thoughts of any kind? 4300 defenders?
  • Sponsors(?)


Well-Known Member
Apr 25, 2009
Southeastern Pennsylvania
Well, the 4300 can be retuned to work well, but the 1.08 4100 is somewhat larger, and IMHO, superior in any respect. A 1.08 from a 289 will work perfectly on your 302, If you have upgraded the cam, get a 1.12 that's been adjusted to work on the 289/302. Put your 4300 in a box for the day you want to show the car.


Founding Member
Aug 21, 2002
lubbock, texas
Visit site
the 4100 is a great carb, no doubt about it. i think for your application a 1.12 4100 from a 352 would work well. there was also a 4100 made in 68 and 69 for the 428 police interceptor engines and a few early 68 shelby's got it as well since they used the PI engine until the CJ came out later in 68. it also appears that the venturi clusters from one of the new Summit versions of the old holley 4010 carb will work on the 4100 as the spacing is all the same and they attach exactly the same as the 4100's venturi clusters, which could be a great tuning aid. i plan on trying this myself at some point.
Thread starter Similar threads Forum Replies Date
1978Cobra2 Engine Worn Pushrods, Loose Rockers. Little Patience 1974 - 1978 Mustang II Talk & Tech 19
allcarfan patience..... 2010 - 2014 Specific Tech 21
thomsonc patience please... SN95 4.6L Mustang Tech 1
E Patience Pays Off 2005 - 2014 S-197 Mustang -General/Talk- 5
B Very Close To Loosing My Mind And Patience!!! Fox 5.0 Mustang Tech 4
H rusted bolts...losing patience 1994 - 1995 Specific Tech 13
V Autolite 4100 Secondary Diaphragm Lever replacement 1965 - 1973 Classic Mustangs -General/Talk- 2
T Plugs - NGK or Autolite? 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 10
S Progress Thread C6AF F 6A F 4bbl Autolite 1965 - 1973 Classic Mustangs -General/Talk- 2
M Autolite 1100 1965 - 1973 Classic Mustangs -General/Talk- 4
Sweetmarie66 2100 Autolite Carb Classic Mustang Specific Tech 8
M Autolite 4100 Trouble 1965 - 1973 Classic Mustangs -General/Talk- 2
Steve491 Expired Autolite Ht1 Plugs, Oil Filters, And Fuel Filter Engine and Power Adder 0
billison Had To Get Autolite 2546 For A 88. 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 18
Nick Bos 1970 Mustang 302-2v Carb? Classic Mustang Specific Tech 1
sen2two Autolite 25 Plugs 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 8
THEUNDERCOATER Gap For Autolite 25 Fox 5.0 Mustang Tech 5
A Need Autolite 4100 Help Asap.. 1965 - 1973 Classic Mustangs -General/Talk- 1
R Expired Rare Autolite 4 Barrel In Line Carburertor Engine and Power Adder 0
M Autolite 4100 Secondaries Driving Me Nuts 1965 - 1973 Classic Mustangs -General/Talk- 5
skiwesser11 Questions About Autolite Spark Plugs Fox 5.0 Mustang Tech 2
cptawesome 66 I6 Autolite 1100 Install Won't Start The Welcome Wagon 4
Davidx9x Expired Autolites Ht1, Valve/tb Covers, Towr Brace, Cams, Gears, Steeda Ud Pulleys, Tails, Saleen Axleback Engine and Power Adder 1
65-Fstbk Autolite 4100 1.08 Vs 1.12 Classic Mustang Specific Tech 4
ZachMartin68 SOLD Autolite 4100 4 Barrel Carburetor VERY lightly used!!! Engine and Power Adder 4
B Any difference in Motorcraft SP498 and Autolite AP5143 spark plugs? 2005 - 2014 Specific V6 Tech 1
phendyr Options For Salvaging An Autolite 2100 Carburetor Classic Mustang Specific Tech 3
E Autolite Battery Cover - Need Battery Rec Classic Mustang Specific Tech 0
O Flooded Autolite 1100??? Classic Mustang Specific Tech 11
BlackVert Autolite 4100 troubleshooting Classic Mustang Specific Tech 3
Dougsters For Sale Autolite 2100 1.23 Vent. 354 CFM Engine and Power Adder 1
Dougsters Rebuilt my Autolite 2100 but have a float level question ? Classic Mustang Specific Tech 4
BlackVert Rebuilding an Autolite 4100 carb Classic Mustang Specific Tech 16
J Autolite 4100 4V question Classic Mustang Specific Tech 4
G Eight New Autolite HT0 Spark Plugs for Sale Engine and Power Adder 2
madspeed Autolite Sparkplugs....REBATE!! Fox 5.0 Mustang Tech 2
G 4100 autolite carb Engine and Power Adder 0
JC Mustang Autolite 4100 float height, adjustments Classic Mustang Specific Tech 5
JC Mustang Autolite 4100 fuel filter Classic Mustang Specific Tech 4
1 Autolite stater part # Classic Mustang Specific Tech 0
R Autolite 4100 Choke Stuck off Classic Mustang Specific Tech 1
hollywoodstang Nitrous and 24 autolite plugs? 1994 - 1995 Specific Tech 6
H autolite 4100 carbs Engine and Power Adder 2
M Anyone use Autolite XP-103 spark plugs? SN95 4.6L Mustang Tech 5
JC Mustang Autolite 4100 Cal emissions difference? Classic Mustang Specific Tech 3
sldghmr Male terminal dist cap for Autolite dizzy?? Classic Mustang Specific Tech 2
JC Mustang Motorcraft/Autolite 4300? Classic Mustang Specific Tech 5
B Autolite 2100 with stock 87 HO !?! Fox 5.0 Mustang Tech 3
Platonic Solid 2100 Autolite/Motorcraft Rebuild Classic Mustang Specific Tech 3
P Anyone get a bunch of misfires from autolite copper cores? 1994 - 1995 Specific Tech 5
Similar threads