I've read some buzz on stock 4bbl carbs.

[Edster]

Seems like Pony Carbs and others have boasted the advantage of the stock 480 cfm carb over other brands. Albeit an excellent design but doesn't total airflow have an effect on this? Common sense would seem to apply here. Maybe putting the larger 600cfm on a mild small block that had the 480 would seem a whole lot better. I'm not sure if these folks are trying to make money on an old design or what. One would think that a Demon or and Edelbrock would bre better as they appear to have been re-engineered from the original design.

 

[rbohm]

remember that carbs operate on vacuum, and that smaller carbs have a stronger signal at the venturi's for better fuel atomization, and thus a more consistent fuel mixture. most small engines dont need 600cfm to perform well, in fact many prefer a smaller carb. if you are going to turn the rpms up, then is where the larger carbs shine as the extra airflow that is available comes into play. i have used the small autolite carbs on mildly built but otherwise healthy engines, and have not lost any performance in the normal driving regime, but i did gain a fair amount in fuel economy, on average about 2-3mpg over a holley or edelbrock carb.

 

[D.Hearne]

The only thing better about the Holley/Demon or the Carter/Edelbrock is they're more "tunable" over the Autolite 4100. Like rbohm says, larger isn't always better when it comes to carbs. It depends on how you're going to use it. If you're looking to use it primarily on the street, smaller is better. If you're looking for all out performance, a larger carb may be what you want-------up to a point. That point is when the vacuum pull drops off to zero at WOT. There has to be some vaccum at WOT for it to function.

 

[bnickel]

if you were to use a pre-64 autolite 4100 you could use standard holley jets to tune it (or so i've read on quite a few 4100 boards, haven't got one to try it myself yet) also any ford 2v carb can be a wealth of tunig parts for the 4100 as well, you can swap the primary boosters from a 2v onto the 4100, the electric choke will swap over and you can even use a later 2v electric AC idle compensater on the 4100 as well. if you get real luckey and find one of the ultra-rare 650cfm 1.19 venturi 4100 from a 58 mercury 352 even better, but good luck on that one, i've only ever seen one of them. that would be an awesome carb to find and use on a healthy big inch small block. i think it would be the ultimate sleeper carb on a stock looking stealth motor.

 

[BornInAFord]

I think Pony Carbs is now building a hybrid of the 4100 series, using the 1.08 for the primaries and the 1.12 for the secondaries. This seems like a good compromise between the 480 and 600CFM carburetors.

I use the original 480CFM 4100 myself on my 66 coupe and really like it. Excellent throttle response, and with the annular venturies (really ahead of their time), excellent fuel mileage, even after over 400,000 miles worth of fuel and 40 years of wear. The T5z I have (and driving style) really helps with the mileage, but 25+ MPG on the highway is pretty good fuel efficiency for an old carbureted car. After I rebuild and tune the carburetor and dial in the engine, I expect even better. My build is a roller 5.0L with Weiand Stealth intake, Performer heads, HO cam, 1.7 roller rockers, 0.63:1 overdrive and 3.40 track-loc rear. I don't baby the car, either.
Daniel

 

[bnickel]

yes, they will use a 1.12 venturi carb and sleeve the primary bore down to a 1.08 size. your build sounds awesome. if you'll run at least 10-10.5:1 comrpession with those aluminum heads you'll get even better mileage

 

[Gud T.B. Blown]

What about the Predator/Kendig carb? Single variable venturi, what are the pros and cons of this design? Supposedly they are good for just about any driving condition. If I understand how this type of carb works (any maybe I don't) this would seem to be an ideal product, yet hardly anybody uses them compared to Holley, Demon, or Edelbrock carbs.
http://www.predatorcarb.com/performance/carburetor.html

 

[rbohm]

the predator is an interesting carb, and is an easy carb to tune. the problem with the predator though is that it is a bit slow to react to changes in air flow, especially compared to other carbs that you listed. it was used on a few race cars in the late 70's and early 80's with mixed results. most guys that ran them did so for a short period of time, and then switched back to the holleys they were running before. in fact there was only one guy that i know of that stayed with the carb for more than a few races, and he eventually switched back.

 

[bnickel]

yeah the only "racers" i know of that still use the predator are the monster truck guys.

 

[D.Hearne]

I think the Predator's down fall is it's so butt ugly. Doesn't even look like a carb. A styling change would do it wonders.

 

[BornInAFord]

yes, they will use a 1.12 venturi carb and sleeve the primary bore down to a 1.08 size. your build sounds awesome. if you'll run at least 10-10.5:1 comrpession with those aluminum heads you'll get even better mileage

The heads are milled so I'm at around 9.7:1 compression right now. Maybe if I ever need a rebuild I'll bump the compression up with domed pistons. I've found the stock HO cam is pretty decent--really wide torque band and it still pulls strong past 6K, something I didn't expect with a factory grind designed for the street. I was going to have it dyno tuned this week, but with the snow/rain here right now I'll have to wait until early next year. Besides, I have to pull the intake and reseal the front intake gasket seal before I really get serious. I still have under $1K in the engine/heads/intake and under $2K counting the tranny and rear.

I really like the 4100... I wish some new ones were made or at least an updated one based on it, but I suppose we'll have to make do with the 40 year old ones that are left. The carb is very efficient and makes decent power.

Daniel

 

[BornInAFord]

IIRC, one of Pony's secrets is to bore the venturis out a bit and polish the inside to increase air flow past the annular venturis and remove any casting flash. I'm not sure what all their secrets are but they do have some expertise/experience in getting these carbs tuned well. Their "set timing/tune by ear" bit has not worked for me, though.

 

[D.Hearne]

If you think the H.O. cam is great, you ought to try the 94-2001 F4TE roller. Best cam I've ever used with a carb. I've got it in my 89 Ranger's 5.0 with 1.7 rockers, a Ford A321 intake and a Holley 570SA carb. If you drove it and I didn't tell you it had a carb, you'd never guess. Pulls from idle to 6000. No pump shot to prime it for starting. No choke either. This cam has slightly less duration & and .030 less lift on the intake side but with a little wider LSA---116*. Advertised duration is 256/266, lift with 1.7's is .445/.473

 

[Helmantel]

The 2100/4100 Autolite carbs are good, although Pony Carbs tends to exaggerate a bit, IMHO.

Came to think of an interesting experiment, similar to what Pony Carbs does: use one large and one small sized 2100 carb (they came with .98, 1.01, 1.02, 1.08, 1.14, 1.21, 1.23, and the hard to find 1.33 venturis), cut out the venturis and make them into sleeves that you then fit into a 4100 body with drilled out the venturis. The boosters of the 2 barrels and thottle blades + shafts can be used, to ensure a good match with the venturis.

The result will be the "best spread bore carb ever made"

Probably not very realistic though.....

 

[bnickel]

i'm fairly certain that's how pony carbs does it, or something very similar anyway. you could always make a silicone mold of the venturi you want to use and sand cast it in aluminum (might even be able to use a silicone cast rather sand as well) then machine the carb to accept the new sleeve and just melt down that 2v carb to make the venturi.