4 Barrel Carb

[jeepguy1948]

Wondering if anybody has tried a 4 barrel on their banger engine? Mostly this question is simply curiosity I doubt I would do it but who knows. How about some 2 barrel carb (other than Webber) with progressive linkage?

[nkaminar]

No doubt someone has tried it. If all the throttle plates open at the same time the air flow through the venturis will not be enough to suck in the required fuel. You would have to use a progressive arrangement where the second set of throttle plates are opened with vacuum in the intake manifold. That way the second set of throttle plates only open up when there is sufficient air flow.

In my opinion, the 4 barrel carburetor would only be valuable if the engine was tricked out and capable of turning over 4,000 rpm. Maybe a race engine with an overhead valve conversion. And, in that case, I would like to see 4 separate side draft carburetors, or two two-throat side draft carburetors, perhaps Webbers.

My down draft Webber has progressive linkage, like you suggested. The second throat only opens up when you put the pedal to the metal. It works great and you can really feel the second barrel coming on.

[Pete]

Originally Posted by jeepguy1948

Wondering if anybody has tried a 4 barrel on their banger engine? Mostly this question is simply curiosity I doubt I would do it but who knows. How about some 2 barrel carb (other than Webber) with progressive linkage?

I ran a 750 Holley on a 215 ci flathead "B" engine on av gas.

It won most of the races it was in.(vintage circle track) Won it's class (M2) in the nationals hill climb at Riverside in 02. Drove it all over LA while we were there. It had a very lopey idle but was very easy to drive on the street. The average daytime temperature was 104 while were there. No overheating. The engine was in a 30 2 door at Riverside. Normally it was in a vintage track roadster.

So, yes, actually several have tried a 4 barrel on a flathead 4 banger A/B engine.
You will probably need about a 20K investment under the carb to make it work really well though.

[updraught]

A Holly 350 would be heaps, but probably similar to a Weber.
A 350 works well on our Holden GM six cyl 186 or 202 cubes, but has more revs.

[BRENT in 10-uh-C]

In essence, the two-deuce manifold with 2 Holley 97s or 94s is the same as one four-barrel 350 CFM carb.

Maybe Pete, Jim, and others will chime in with their thoughts too, but as I understand this, the biggest issue that a typical A/B flathead banger faces is something that using a larger carburetor really does not cure which is the the siamesed intake ports and the back-to-back firing order. Using the front intake port as the example, as the #1 intake valve opens, the vacuum of the lowering piston draws air & fuel into the #1 cylinder with a level of velocity. Then when that piston is at BDC, the valve closes causing the need for the rushing air & fuel to change directions which is not good for air flow nor keeping the fuel in suspension. One of the biggest ways to circumvent this have a large enough plenum to temporarily store enough fuel & air to fill the #2 cylinder too. I listened to Dick McKee and Dan Price get into a debate about this one evening after races and this is evidently why long runners or log manifolds were so popular.

[Flathead]

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Originally Posted by Pete

I ran a 750 Holley on a 215 ci flathead "B" engine on av gas.

It won most of the races it was in.(vintage circle track) Won it's class (M2) in the nationals hill climb at Riverside in 02. Drove it all over LA while we were there. It had a very lopey idle but was vey easy to drive on the street. The average daytime temperature was 104 while were there. No overheating. The engine was in a 30 2 door at Riverside. Normally it was in a vintage track roadster.

So, yes, actually several have tried a 4 barrel on a flathead 4 banger A/B engine.
You will probably need about a 20K investment under the carb to make it work really well though.

I expected to see an overhead but no, all that with a Flathead! I can understand the 20K commitment to make it happen.

[johnneilson]

Originally Posted by Pete

I ran a 750 Holley on a 215 ci flathead "B" engine on av gas.

It won most of the races it was in.(vintage circle track) Won it's class (M2) in the nationals hill climb at Riverside in 02. Drove it all over LA while we were there. It had a very lopey idle but was vey easy to drive on the street. The average daytime temperature was 104 while were there. No overheating. The engine was in a 30 2 door at Riverside. Normally it was in a vintage track roadster.

So, yes, actually several have tried a 4 barrel on a flathead 4 banger A/B engine.
You will probably need about a 20K investment under the carb to make it work really well though.

Pete,

That manifold looks to be a 4 port setup, did you dig out the siamese port and split it into 4 seperate ports? or did you reverse the ports?

John

[Jim Brierley]

I've run a 350 Holley 4 bbl on the dyno on the new Serr/Miller 4-port, 225 HP at 5300 RPM. Manifold was a plenum type, the engine was built for touring, not all-out racing. We tried a 600 Holley and the power went down a bit. I've run 1,2, and 3 Strombergs on flathead bangers, none with progressive linkage, all ran great thru all RPM ranges, as tested on hill climbs. All ran best with stock jets although with 3 carbs I only ran 2 power valves. Last January we dynoed my Winfield 6:1 with 3 carbs, 96 HP, stock size valves, mild performance cam. We then swapped the Winfield for my 7:1 BRIERLEY head, HP went to 107. Then by changing only the throttle linkage we ran two 81 carbs, 106 HP, then one 97, 102 HP. I've also run a 38/38 Weber and a 45 DCOE (#34 chokes) Weber on my Riley 4-port, with minor jet changes both ran great. I prefer the DCOE because it looks very cool!

[jeepguy1948]

My interest is more about driveability than outright performance. I’m primarily thinking about the benefits of progressive linkage without getting into multiple carburetors. A 2 barrel with progressive linkage would be good I think but I am unaware of any other than the Webber. Also, I don’t know what the smallest 4 barrel (that is readily available) is. I do know this, the banger is a 200 CI motor, I think it can use more air than can get through a 1” carburetor (that being why the B carb provides some performance improvement). In reality, the Webber is probably the best but they are simply too complicated with too many circuits for me.

[Pete]

Originally Posted by johnneilson

Pete,

That manifold looks to be a 4 port setup, did you dig out the siamese port and split it into 4 seperate ports? or did you reverse the ports?

John

I machined away the area around the ports and welded in 2 seperate ones.
A clone of this engine won the vintage 4 banger dragster class at the Antique Nationals,2 years. Beat all the overheads.

[David in San Antonio]

I wonder if anyone on here (maybe from UK?) ever experimented with SU constant velocity carbs? As the name suggests they maintain the air velocity through the Venturi. Their lineup begins with very small throat size which Little British Cars (LBCs) used for decades. I would imagine 1 or more of these could work well on an A.

[Jim Brierley]

I've run two 97's and three 81's all opening at the same time with no problems. These engines will take a lot of air. From what you are saying, I would suggest one Stromberg 97, with all stock jets.

[jeepguy1948]

Thanks Jim I think that that’s what I’m going to do, I have a manifold on it’s way.

[walls]

Originally Posted by jeepguy1948

In reality, the Webber is probably the best but they are simply too complicated with too many circuits for me.

I wouldn’t fear the Weber. I setup duals on a Chevy 250 once and they worked great. I’m no genius when it comes to this stuff.

I’ve recently been emailing with Jim a few questions on one of his heads that I purchased. He’s probably forgotten more than I know, but I would tend to agree with him. A single 97 works very well.
43 main jet 71 PV is what I used on a stock model A with 6.0 Snyder head and it ran great. Start with stock jets.

[jeepguy1948]

Just curious, what are the results when using a single 81? I know nothing about those carbs

[Jim Brierley]

Originally Posted by jeepguy1948

Just curious, what are the results when using a single 81? I know nothing about those carbs

Years ago I ran a hill climb in Auburn, CA. I first ran it with stock manifold and carb. A few months later I ran the same hill with a 6:1 Winfield head, it was a full second quicker on the 1/10 mile course. That same day I switched to a single 81, times were nearly another second quicker. Later I switched to a 97 and gained another 3/10s of a second.

I have done some dyno work on a different engine out of my speedster. Engine specs are 6:1 Winfield head, mild performance cam, stock size valves, two 81 carbs and one 97. Results were 96 HP @ 3200 RPM. I then swapped the head for one of my heads which are 7:1, so not a perfect comparison but that's all I had. HP went up to 107 @ 3400 RPM. I then changed carbs by merely changing the linkage. With two 81's the power only went down about 1 1/2 HP. With the single 97 it dropped to 101, not as much as I thought it would.

[A model Thom]

I know its slightly off topic for the thread but have many people run a 94 on their banger, I swapped from a 97 to a 94 (the larger version from a 55 272) on my warmed up banger (7:1 lionspeed head, ported block, reground b cam, burns intake, home made 4 into 1 header and an fsi electronic distributor) in my otherwise stock 30 town sedan and have been quite impressed with the improvement over the 97, while it seems to make similar power it has definitely improved economy and is much more responsive than the 97, I'm curious to see if many people have tried a 94 on their banger

[Bruce of MN]

beautiful!

[johnneilson]

I have been running 94’s for some time
Personally my street cars have single setups
They are really reliable and I don’t have to monkey with them
I do enough monkey business on the racers

[Dale'45]

If I remember right the pre injection 2.4 liter Toyota pickup engines ran a progressive two barrel carburetor. Dale