6.1 Head / Carburetor Choice / 600 HP V8

[Model A Ron]

I have the need to get a new Carburetor as my Zenith is striped out and needs a rebuild.

That said would the Zenith Carburetor be a good match for the 6.1 head or should I consider something different.

Thanks
Ron

By the way the 600 HP is Satire for the haters. I am not building a hot rod nor do I want one. I am looking for better drivability between 50 and 60 mph......this is not outside of the Model A's capability.

[CarlG]

1) I have a 5.5 head and am running a Stromberg 97.

2) Because my engine builder suggested it.

[jayvee34]

I run a 5.5 head and a Zenith Carburetor.
Because I do my own mechanical work and believe the 5.5 head is not to much for
my stock engine lower end. I rebuilt the Zenith carburetor and it works great. also
I check my sediment bowl regularly and keep it clean, if not, no carburetor will work
right, regardless of the make or type. Very happy with my set up.

[Herb Concord Ca]

With my 5.9 Brumfield head I run a Marvel. I suppose a Model B carburetor would be also.

[Herb Concord Ca]

Second sentence show read, I suppose a Model B carburetor would be good also.

[BRENT in 10-uh-C]

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I install 6:1 (-when they are available) and typically use a rebuilt Model-A Zenith Carburetor. I sometimes will deviate from that if there will be a camshaft change to something like an IB340 camshaft and 1.750 intake valves with enlarged bowls. In that case, I offer to upgrade to a Model-B carburetor and a modified Model-A intake manifold for a tad more airflow. Even with a 6:1 head, IB330 camshaft, and larger valve work, the stock Zenith carburetor that has had the jets flowed will perform satisfactorily.



The two or three things that I would consider for my car is the plumbing required for other carburetors. If running a downdraft carburetor in the mountains, an electric fuel pump is generally needed. Plumbing the fuel system where it is not dangerous is often difficult and expensive to do it properly. The overall aesthetics of the engine compartment is something to consider. We have all discussed how an alternator looks out of place on a restored Model A. I feel a downdraft carburetor does the same. I embrace (-and favor) modifications that assist performance that don't alter aesthetics. When this happens, it really is no longer a restored original car, -but it meets the qualifications of being a street rod (-and nothing wrong with that if that is your goal.).

The third thing in this is what is right for my car vs. what is right for your car is a touchy subject. My advice is you are way too new at Model-A ownership to know what is right or wrong for your own car. You need to drive the car WAY more than 300 miles or so, -and you need to participate with fellow Model-A enthusiasts for awhile before you start making wholesale changes to your car. As you participate in events, there will be certain vehicles that stand out in performance. You will also likely find modified vehicles that are always breaking down or causing drivability issues for the owner. Discussing those cars with their owners will give you a much better understanding for what is right for your car.

[Gene F]

I agree with comment #3. Unless you have big cam, and or larger valves, the Zenith is still a nice choice.

[BRENT in 10-uh-C]

Originally Posted by Herb Concord Ca

With my 5.9 Brumfield head I run a Marvel. I suppose a Model B carburetor would be also.

Originally Posted by Herb Concord Ca

Second sentence show read, I suppose a Model B carburetor would be good also.

Herb, you are on the right track. The Model-A carburetor bore size is almost 1 inch in diameter, -and the Model-B is 1¼" ...which is a great gain in airflow however a Model-A intake manifold has a 1.000" rough-bore draw tube whereas the Model-B intake manifold is 1.250". Bolting the larger carburetor onto a restricted manifold really does not gain anything. The Model-B intake can be modified for use on a Model-A engine however the better alternative IMO is to bore the inside to at least 1.250" to utilize the air flow gain of the Model-B carburetor.

[burner31]

I have the 6:1 head and run the stock Zenith, I have no problems, no issues.
Go for it, see how it works for you.

[Model A Ron]

Originally Posted by BRENT in 10-uh-C

I install 6:1 (-when they are available) and typically use a rebuilt Model-A Zenith Carburetor. I sometimes will deviate from that if there will be a camshaft change to something like an IB340 camshaft and 1.750 intake valves with enlarged bowls. In that case, I offer to upgrade to a Model-B carburetor and a modified Model-A intake manifold for a tad more airflow. Even with a 6:1 head, IB330 camshaft, and larger valve work, the stock Zenith carburetor that has had the jets flowed will perform satisfactorily.



The two or three things that I would consider for my car is the plumbing required for other carburetors. If running a downdraft carburetor in the mountains, an electric fuel pump is generally needed. Plumbing the fuel system where it is not dangerous is often difficult and expensive to do it properly. The overall aesthetics of the engine compartment is something to consider. We have all discussed how an alternator looks out of place on a restored Model A. I feel a downdraft carburetor does the same. I embrace (-and favor) modifications that assist performance that don't alter aesthetics. When this happens, it really is no longer a restored original car, -but it meets the qualifications of being a street rod (-and nothing wrong with that if that is your goal.).

The third thing in this is what is right for my car vs. what is right for your car is a touchy subject. My advice is you are way too new at Model-A ownership to know what is right or wrong for your own car. You need to drive the car WAY more than 300 miles or so, -and you need to participate with fellow Model-A enthusiasts for awhile before you start making wholesale changes to your car. As you participate in events, there will be certain vehicles that stand out in performance. You will also likely find modified vehicles that are always breaking down or causing drivability issues for the owner. Discussing those cars with their owners will give you a much better understanding for what is right for your car.

Brent
You may be right on me getting more experience with a Model A as I am still in the stage of discovering just how simple the Model A is. That is why I am simply asking questions.


Ron

[SAJ]

We have a Tudor and a Roadster both with 5.5 heads and Zenith model B carbs on drilled out A manifolds, with large K& N air cleaners fitted. Both cars will go well over 70 mph flat out and return 22 to 24 imperial mpg on trips cruising at 50 to 55 mph.
I like the almost standard look and nod to originality that the B Zenith gives.
A pump and downdraft is a move too far for me.
Everyone has a different vision for their car though, and a Model B carb is a move too far for some.
I have drilled out a lot of Model A manifolds, presumably for members that fitted B carbs, so I think there must be a lot of cars running B's in New Zealand. These carbs often came up at swap meets here when I was collecting them, which is surprising to me.
SAJ in NZ

[msmaron]

I run a 6:1 head and a B carb and B Dizzy, as Brent terry states above I had the manifold fully bored out as brent stated "1.250" to utilize the air flow gain of the Model-B carburetor." I also run a couple touring engine. I do see a difference for sure...

[Gene F]

I did not know you can bore out the up tube of the A intake. Do they ever snap after you do that?

[Ranchero50]

FWIW it's pretty easy to make a new intake out of some mandrel bent header tubing. This is a B carb feeding a 6-1 head and wobbly piston A block more to help mock up the rest of the car than anything long term. I have a B block that's going to have a Eaton bolted to the timing cover once the body is finished. It'll have considerably more carburation.





Sometimes being unconventional is fun.

[denis4x4]

Nobody has mentioned the Weber 32/36 two barrel carb downdraft. I have A and B high performance engines and use this set up on both of them. In fact just switched the Solex carbs on my Jag for the 32/36 carbs

[Hitman]

There are so many variables in your question, and suggestions here!

You need to be patient, tour with others, figure your car out! How does it compare to other cars? This takes thousands of miles to figure out. But if your goal is to go as fast as it can with bolt on parts, maybe you need something else.

You could fall behind on a tour with a long hill; if your engine is worn, a high compression head only masks the issue. Who knows, maybe your timing is off?

The modern car mentality of changing parts until the problem is solved doesn’t work here.

I think you’ve asked three years worth of questions within three months! You need to slow down, drive the car, and figure out your end goal.

I drive mine, cross country, and can easily do 60-65 all day long. I’ve climbed to over 11,000 ft in elevation numerous times. If I lift the hood, it appears stock to 95% of the “restorers” out there. I got to this point over several years, but lots of testing mileage.

Get out and drive! It’s driving season in your part of thee country. Do it, and worry later. Compare your car to a Model A, not a mustang!

[CWPASADENA]

I have been running a B Carb on a bored out A manifold on a B engine with a 6.0 head in my Tudor that I use for touring. I have many thousands of miles touring with the car and am very pleased. Simple, straight forward, and good performance. I get 18-20 mpg and will run comfortable all day at 60-65 mph. (with a Mitchell Overdrive)

Before I got around to boring out the intake and installing a B carb, I ran a A carb and it ran just fine. I think it runs a little better with the B carb.

I am the technical director of our club and will always run at the back in case someone has a problem. Most "side of the road" repairs are made on cars that have been modified with lots of "Modern" components. The cars that are simple and in keeping with what Henry originally designed seem to be the most reliable. With a very few modifications, they will run at a decent speed all day and go up the hills with no problems.

Also, like has been previously stated, when I raise the hood, it looks like an original engine and not something that has been all cobbled up with a lot of "Modern" stuff. People we meet along the way seem to enjoy seeing a how simple the cars are, especially the old guys when I raise the hood to show them the engine.

My opinion,

Chris W.

[nkaminar]

My car came with a 5.5 head, cam, and Weber. I switched over to the stock Model A manifold and rebuilt Tillotson carburetor. It ran well with the Tillotson, started easier, and had better throttle response, but lacked the power at the high end that the Weber provided. I went back to the Weber to get the increased power at the high end. I like the look of the stock setup better than the Weber.

[old31]

I have 6.1 and model B carb with a bored out intake. Love it!

[McMimmcs]

Originally Posted by CWPASADENA

I have been running a B Carb on a bored out A manifold on a B engine with a 6.0 head in my Tudor that I use for touring. I have many thousands of miles touring with the car and am very pleased. Simple, straight forward, and good performance. I get 18-20 mpg and will run comfortable all day at 60-65 mph. (with a Mitchell Overdrive)

Before I got around to boring out the intake and installing a B carb, I ran a A carb and it ran just fine. I think it runs a little better with the B carb.

I am the technical director of our club and will always run at the back in case someone has a problem. Most "side of the road" repairs are made on cars that have been modified with lots of "Modern" components. The cars that are simple and in keeping with what Henry originally designed seem to be the most reliable. With a very few modifications, they will run at a decent speed all day and go up the hills with no problems.

Also, like has been previously stated, when I raise the hood, it looks like an original engine and not something that has been all cobbled up with a lot of "Modern" stuff. People we meet along the way seem to enjoy seeing a how simple the cars are, especially the old guys when I raise the hood to show them the engine.

My opinion,

Chris W.

Thanks Chris seems like as soon as many buy a Model A they want something faster and different. Different head, cam, carburetor, tires and whatever. Should have bought a hot rod in the first place. I bought it because it was vintage and simple and will keep it that way ! Wayne