This is a feeler to see if anyone has solved the big block Autolite 4100 callibration issues with a Y block, or non big block.  I have tried in the past & finally chalked it off to air bleed incompatibilities for the smaller motor.  I read a posting on here that was reminisent of everything I tried to get the carb to meter properly below 2000 to no avail. 

Has anyone ever successfully done it?

I know Pony Carbs makes a 1.08 that they fit the larger butterflies to the secondary side.  I unfortunatly am without a machine shop, or I would.  I have successfully bored the secondary ventury slightly, as well as slimmed both shafts for significant improvements. 

Thoughts?

The Autolite 4100 was original equip on 65/66 Mustangs with a 289 and 4BBL and was a great carburetor. What kind of issues are you speaking of? It worked on both A/T C4 grocery getters and 271 Hipo 4 speed equipped cars.

It was actually used from 58 through 67, possibly even 68.  I'm pretty sure it was on some 312's, quite a few 289's 352's, 390's, & possibly a few others.  They stopped using it around 67, or 68 to use the 4300 series.  The 289 Hi'Po engines had a 1.12 carb that was correctly metered for a small block... I just don't know what exactly they did to achieve that.  That's what I am trying to solve, then I can make use of the BB carbs I have.

Kevin

I have a 1.12 card that was originally on a 66 7 Litre(428).I've tried to get it to work on my 272,but haven't been able to lean it down enough.I'm in the process of making a restrictor plate with holes the same size as the holes in a 55 teapot carb.It will be on a stock 272 with a late intake.

 

Paul,

Boonville,MO

Since most of the fuel metering in a 4100 occurs in the venturi cluster, has anyone tried using a 1.08 cluster on a 1.12 body?

I Tried using the 1.08 booster venturies from my reman carb. I also tried a variety of different boosters that had different size pressure bleeds & siphoning tubes.  None produced a correct combo.  I tried using different jet sizes, & changed each part in a scientific manner so as not to change too much at once.. Other than weart out gakets I couldn't get it to meter. 

It was a lean running condition from Idle through cruise.  I could obviously offset this some by putting fat jets in & putting the accelerator pump on generous settings. But even when I did this you could tell that it wasn't right.  It was  over compensating for a lean condition. I tried an entirely different 1.12.  Repeated the process, same basic problem.  The second I put my 1.08 on with it's correct boosters, back to a smooth transition. Idle, cruise, wot.

I tried to use a big block 2bbl years ago, 1993?? (autolite 2100), & ran it for about a month & almost burned valves! I was younger & still learning alot about carbs & was exstatic to get such great mileage & have a healthy carb moan on my then stock 292.  What I soon realized after lean fouling plugs(yes it is possible) was that it was trying to run at something like a lean burn chrysler would.(around 18:1+-)  Remember Stoich is 14.7. So after having my Dad & his master tech chew my A** for tinkering too much I returned it to the stock 2100 small block carb with slight mods to the throttle shaft & a carefully tuned powervalve.

I would love to be able to figure this out, especially since 1.12's are still in fair supply.

Kevin

Red Stake:

With your knowledge of carburetor design, I'm surprised you did not see the problem.  The carb is too big.  It takes very little throttle opening to maintain rpm above idle, but the main fuel system is not delivering enough fuel because the venturi vacuum is nearly non-existant, and the idle system is not big enough to flow enough fuel at that rpm.  That's why your 108 works better, it is better sized to your engine.

John

John - "The Hoosier Hurricane"

Well John, as long as your up this AM. I've have most of the bugs worked out of my 650 Holley for now but am getting really bad gas mileage (10 mpg or less). Other than the heavy right foot any ideas?

Chuck

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Thanks John.  I guess I didn't think of it like that way. 

Ok, so I guess the large primary's of the 1.12 could be my obstical. I wonder if I could find early carter venturi that could be made to fit the primary side of the 1.12?  I did once try an early Q-Jet on my y block, but couldn't get the vac. adv to run, & then I had to get it ready for a move cross country, so I went back to the 1.08.  The throttle response was ausome! Even without proper Vac. adv.

I did find an interesting tid bit on the Pony Carb site: I think this applies to the Y block as well, so hope no one minds my posting it. The link should bring up a FAQ section on the 4100 1.12 "spreadbore".

http://www.ponycarburetors.com/default.asp?page=faqdetail&id=19

Chuck:

My first thought is a power valve issue.  Bad diaphragm, bad gasket, or vacuum rating too high.

John

John - "The Hoosier Hurricane"