B-carb on A-block

F

Feurst choice

Junior Member
Do You assume that an B-carb with modified A-intake on a standard A-engine will provided lower or higher mileage than an stock A-carb?
 
Feurst choice said:
Do You assume that an B-carb with modified A-intake on a standard A-engine will provided lower or higher mileage than an stock A-carb?
Click to expand...

To answer your question correctly depends on many things. It could make your engine more efficient, -or it could be over-carbureting which would waste fuel. In a nutshell though, the bore size of a typical Zenith supplied on a Model-A engine is 1.000" throttle bore size. The Model-B has that size increase to 1.250". Does that make sense what I am saying??

Also, since this is your first post here, -welcome to Fordbarn! :cool:
 
Are you worried about minute gas mileage difference, or performance differences?
I have a .125” bored,hotter cam, B carb with hogged out intake, electronic ignition, and while I was running a 3:78 differential, depending on speed of course, I got well over twenty mpg. Don’t worry about a small change in mileage, if any. I might add, if your current carb isn’t correct, then you’ll be seeing bad mileage.
 
OK! They guy who sold it said I might not expect more horsepower - maybe just a pony!
I will test and report back…
Thanks for the welcome!
 
I run a B carburettor on an A motor with a bored out manifold. It also has a 5.5:1 head, well, that's where it started but it's more like 7:1 now and I have a small cam in it. Power is up on the original motor by quite a bit but economy is down a bit too. You can't get power without burning fuel. More power - more fuel. Simple.
 
Raising engine efficiency increases power without using more fuel. The stock model a is detuned, raising compression and adding fuel raises the efficiency of the engine, done correctly your fuel ‘mileage’ will increase.
 
jack backer said:
Raising engine efficiency increases power without using more fuel. The stock model a is detuned, raising compression and adding fuel raises the efficiency of the engine, done correctly your fuel ‘mileage’ will increase.
Click to expand...

Some truth in there but I wouldn't consider simply adding a B carburettor doing it correctly. There would have to be other measures taken.
 
Synchro909 said:
Some truth in there but I wouldn't consider simply adding a B carburettor doing it correctly. There would have to be other measures taken.
Click to expand...



Adding a B carb correctly raises efficiency. The B carb flows air at a higher rate than an A carb due to its larger venturi. The A carb flows air at about 80CFM. I would estimate the B at 90 CFM. The Model A engine flows at approximately 160 CFM, Which is why a Stromberg 97/ Holley 94 / Weber 32/36at appx. 170 to 190 CFM maximizes the A engine power and efficiency. So, I would say there is no truth in your B carb statement.
 
jack backer said:
Adding a B carb correctly raises efficiency. The B carb flows air at a higher rate than an A carb due to its larger venturi. The A carb flows air at about 80CFM. I would estimate the B at 90 CFM. The Model A engine flows at approximately 160 CFM, Which is why a Stromberg 97/ Holley 94 / Weber 32/36at appx. 170 to 190 CFM maximizes the A engine power and efficiency. So, I would say there is no truth in your B carb statement.
Click to expand...

Are you saying that simply putting on a Larger carburettor is all that one can do to improve the efficiency of the engine? How about higher compression head and a different cam? For about a century, to get more out of a low efficiency motor, attention to the three "Cs" is what would do it. A small change to Carb, Cam and Compression makes a big difference when done together and correctly - much more than just the larger carburettor on its own.
I stand by my comment. Let's hear from others.
 
More Compression, Lighter flywheel, Better lubricity, better balancing, are all things that will make your car run better without putting more gas in the cylinder. However, The stock Mod A engine layout for gas distribution leaves a lot to be desired. The purpose of boring an A manifold is to create to only a larger (carb) runner to accommodate the two runners, but to create a smoother surface than the original cast surface that the factory sent it out with. This will allow a faster flow of the air/gas mixture in the cylinder. Ditto for cams! Lightened flywheels allow the engine to spool up faster. A stock flywheel weighs 63 lbs, which is not needed on today's roads, with today's gasoline. When I had access to a big lathe, I cut a few down to about 54lbs (plenty heavy) and that was effective for what I wanted. But I was switching engines. I would not do the work of pulling an engine just to hack away at a flywheel. I would suggest you buy a Snyders 5.5 or a 6 to 1 C.R.head to increase the compression. With these simple Mods (Excluding flywheel) your car will 50 to 55 hp and you'll be able to keep up with highway traffic. For more info, go to Piranios, model A Dyno readings. Good Luck!
 
I believe that larger intake valves go along with the 3 C's, carburetor(B), compression(Brumfield), cam(Stipe 340) to get the best performance.
 
jack backer said:
Raising engine efficiency increases power without using more fuel. The stock model a is detuned, raising compression and adding fuel raises the efficiency of the engine, done correctly your fuel ‘mileage’ will increase.
Click to expand...

"...done correctly..." And more important: Driven correctly! When we have more power under our right foot, we tend to use it, thus wasting that new-found efficiency!
 
The original topic was the benefit from adding fuel alone.. to maximize the output of any engine and the A engine particularly all engine functions have to be improved ( cam, fuel, compression, exhaust and ignition) to realize full potential with the L head design.. it basically doubles the power and torque of the stock engine.

40 Deluxe, keeping your hoof out of it is the hardest thing to do.. the A’s low end torque rises as well, it’s a hoot to catch someone driving a Kia and school them for a bit .
 

Attachments

  • CDAE1121-598F-4DB9-92C4-A5D2220F9665.jpg
    CDAE1121-598F-4DB9-92C4-A5D2220F9665.jpg
    89.3 KB · Views: 13
Purists don’t appreciate modifiers.. the model A from the late 30’s was raced and modified, it’s part of its heritage, the clubs came along and focused on restoration, and modifying fell by the wayside with the V8 taking the lead.. today, modifying has seen a resurgence.
 
You must log in or register to reply here.
Back
Top