Rajo B carburetor selection

Reno Speedster · Post by **Reno Speedster** » Wed Mar 02, 2022 7:53 pm

I did a search of the forum for this but didn’t really get an answer. So here goes.

Now that my Rajo B head is at the shop getting rebuilt (they confirmed yesterday that it had no cracks and are getting to work on it), I need to figure out what carb(s) to run on it.

I will need to make the intake and want to stick with 1927 and earlier equipment. I have some Zenith 04 carbs around that would need to be rebuilt and I have thought it might be cool to run a pair of them with a foot throttle. But, I don’t know if that would be a good approach.

What I am interested in finding is a setup that will run well, will not cost a fortune, or take a years long quest to find. I know this may be an impossible set of conditions but living in Alaska, it’s hard for me to find the exotic bits.

What are people running and does anyone have a solution that might fit my bill?

Thanks

Kevin Pharis · Post by **Kevin Pharis** » Wed Mar 02, 2022 8:05 pm

Here’s another nice Zenith O4 with a parts carb...

viewtopic.php?f=5&t=27030

Reno Speedster · Post by **Reno Speedster** » Wed Mar 02, 2022 8:13 pm

I have one of the zeniths that was built for use on the T with the throttle body turned 90 degrees from standard, along with a cast iron zenith manifold. It’s a nice setup, but won’t work on the B. I have a couple of normal 04s that would look good as a pair (if the would fit).

Kevin Pharis · Post by **Kevin Pharis** » Wed Mar 02, 2022 8:22 pm

Here is a shot of a ‘25 Winfield catalog showing a 1-1/4” (5V) carb for use on a B RAJO. Or if racing and want 2 carbs, you get a pair of 1-1/2” (6V) carbs

Reno Speedster · Post by **Reno Speedster** » Wed Mar 02, 2022 9:17 pm

Very cool, but thin on the ground.

Mike Lebsack-Iowa · Post by **Mike Lebsack-Iowa** » Wed Mar 02, 2022 9:27 pm

Have heard that a Carter BB1 with an adjustable main jet is no slouch either.

babychadwick · Post by **babychadwick** » Wed Mar 02, 2022 10:45 pm

Might look for a winfield model M, not as hard to find as the V or H, typically they are cracked due to the weight of the choke but that just gives you the option to use a simpler choke. You are probably going to want a larger single but it might be easier to find a pair of smaller.

Reno Speedster · Post by **Reno Speedster** » Wed Mar 02, 2022 11:04 pm

Mike Lebsack-Iowa wrote: ↑
Wed Mar 02, 2022 9:27 pm
Have heard that a Carter BB1 with an adjustable main jet is no slouch either.

Interesting idea. They appear to be cheaper than others. There are a number of different versions. I wonder which one would be best.

Kevin Pharis · Post by **Kevin Pharis** » Wed Mar 02, 2022 11:22 pm

Cheap, available, and many variations in size. Authentic to the 50’s era too...

babychadwick · Post by **babychadwick** » Wed Mar 02, 2022 11:23 pm

Kevin Pharis wrote: ↑
Wed Mar 02, 2022 11:22 pm
Cheap, available, and many variations in size. Authentic to the 50’s era too...

But not pre '28 as he had requested

Reno Speedster · Post by **Reno Speedster** » Wed Mar 02, 2022 11:40 pm

That is a rub.

Post by **pete eastwood** » Thu Mar 03, 2022 12:23 am

Carter BB 1 was available in the early 1930's

jmemjr · Post by **jmemjr** » Thu Mar 03, 2022 8:25 am

Carter BB1, I ran it on two set-ups and it was a good fit. Call Gene Tesch from NJ he rebuilds them

Post by **Craig Leach** » Thu Mar 03, 2022 10:21 am

I prefer a Marval Shebler for a model A. We took a BB1 & BB2 off a freinds A crank/cam & T-GO head engine and installed one on it. Lost a little performance but gained adjustability and driveability. I have the BB1 & BB2 available if anyone is interested.
Craig.

Post by **rnkugel** » Thu Mar 03, 2022 10:56 am

I have a RAJO C head on my speedster and run a Rayfield UF. Fits standard T intake and supplies plenty of fuel. Good luck on your search.

Tracer · Post by **Tracer** » Thu Mar 03, 2022 9:03 pm

I run a Model S size B winfield on my BB rajo

Mike Lebsack-Iowa · Post by **Mike Lebsack-Iowa** » Thu Mar 03, 2022 9:49 pm

Rayfield UF, beautiful carburetor, yep, they can still be found.

Wayne Sheldon · Post by **Wayne Sheldon** » Thu Mar 03, 2022 11:58 pm

I am not sure exactly what you are looking for? But, it does sound like you want actual era correct items. To my way of thinking? That is the best way!

One of the things I have really missed in this hobby for the past twenty plus years, is talking with the people that actually built and raced model Ts back in the 1920s and early 1930s. They all moved on some time ago. But when I was first getting into this hobby? A lot of them were still around. Several of them became good friends, even my mentors when I was in high school and for several years after. I often drove my first model T speedster to almost anywhere. And people would come up to me and tell me about the one they raced back in 1920-something! I really miss that.

One thing I heard from several old-timers back then. But I haven't seen mentioned here yet, is that one of the favorite carburetors for racing model Ts back in the 1920s? Was the common Chevrolet Carter updraft carburetor! They were common back then, still are. And they were cheap back then for young men on a budget.
One of my early mentors raced a model T in the late 1920s. He loved to talk about those days, and I loved to listen to his stories. He and his buddy built a good car, eight valve overhead, and a bunch of other good stuff. They had two manifold and carburetor setups for the car. One had a pair of updraft Winfields (this was before the downdrafts were introduced in 1929!). The other manifold had two Carter updrafts.
They would prep the car days before a race. And they would usually begin adjusting the Winfields. But, the Winfields were finicky. Sometimes they would set up and work great! If so, the car would do a bit better than it could with the Carters. Sometimes, the Winfields simply did not cooperate. But the Carters always worked fine. Sometimes they would have it all set up the day before a race and the Winfields were just singing a beautiful tune! But the day of the race? Nothing but sour notes. Literally minutes before the race would start, they might have to swap the manifolds and run the Carters. The Carters always worked fine.

I never have run an OHV on a model T. But one of my cars was a resurrected racing car with a highly modified T block with four cylinder Dodge valves that touched the edge of the cylinders, and ground oversize passageways taken as big and smooth as one could dare attempt! On that car, I ran a single Chevrolet Carter updraft carburetor.
One time. Just to see if it could do it. I "spun a donut" on dry pavement. It did it.

So it depends a bit on what all you want to have and accomplish? I always try to be very close to era correct. But that is me. If you want to impress people and have the budget to allow it? Can't really beat the Winfields, or a Claudel if you can find one? If on a bit of a budget, or just want to have reliable fun? A single or well set up pair of Carters is a good (and era correct!) way to go?

David Greenlees · Post by **David Greenlees** » Fri Mar 04, 2022 8:29 am

Wayne Sheldon wrote: ↑
Thu Mar 03, 2022 11:58 pm
So it depends a bit on what all you want to have and accomplish? I always try to be very close to era correct. But that is me. If you want to impress people and have the budget to allow it? Can't really beat the Winfields, or a Claudel if you can find one? If on a bit of a budget, or just want to have reliable fun? A single or well set up pair of Carters is a good (and era correct!) way to go?

Wayne, I agree with you. I used to use a single 1928 Chevrolet Carter on a Winfield manifold on my 1924 T York-bodied depot hack and it worked very well. It only issue I had with it was these carbs were setup to run on hot air and in my experience didn't run well without it. Although, that was back in the 1980s when we had good gas. Too much hot air with today's fuel might cause vapor lock in hot weather.

Mike Lebsack-Iowa · Post by **Mike Lebsack-Iowa** » Fri Mar 04, 2022 9:00 am

When looking for a Carter BB-1 be sure to find the one that has the adjustable main jet. Some versions do not, and I was told by a gentleman who really knew a lot about running Rajo overheads (John Rogne), that for optimal performance the adjustable main jet is required.

Reno Speedster · Post by **Reno Speedster** » Fri Mar 04, 2022 11:16 am

Thanks for all the input. I am trying to keep the car period. Not everything on the car is original period, but everything was available before 1928.

My goal is to find a period carb for the Rajo that runs well, is reliable, and is not super rare.

David Greenlees · Post by **David Greenlees** » Fri Mar 04, 2022 12:37 pm

Reno Speedster wrote: ↑
Fri Mar 04, 2022 11:16 am
Thanks for all the input. I am trying to keep the car period. Not everything on the car is original period, but everything was available before 1928.

My goal is to find a period carb for the Rajo that runs well, is reliable, and is not super rare.

Are you using an original Rajo manifold?

The Carter carbs both Wayne and myself mentioned earlier doesn't look like the Carter BB1 that looks somewhat modern. The carbs we mentioned have a cast iron body and the float bowl is brass and look like they are from the early '20s. The 28' Chevy Carter is the most advanced 4-cyl. carb model that the Co. made. There are also other versions of this carb for other applications that have a larger throat. They used to sell quite cheap because there are a lot of them that have survived and there are not many cars left to put them on. You could use a pair of them as well for more power.

Follow the link and scroll to the engine photos to see what one looks like.

https://www.vintagecarcollector.com/veh ... ndow-coupe

Reno Speedster · Post by **Reno Speedster** » Fri Mar 04, 2022 1:12 pm

Sadly, I don’t have the original manifolds. But that means I can make them to fit whatever I use.

Dan McEachern · Post by **Dan McEachern** » Fri Mar 04, 2022 1:43 pm

I do have intake and exhaust flanges available so you can make your own manifolds if you wish. You can send me an e-mail at dmcgearsatyahoodotcom
if you would like more information.

Post by **YellowTRacer** » Fri Mar 04, 2022 5:40 pm

We have had excellent performance from the Zenith L-6 bronze carb that is on #2. The carb and manifold was on one of the Rajo racing engines on display at the Harrah's auto museum back in the 1960s. Somehow I ended up with that engine and as we were constructing #2 it had a B head on it and so I robbed the manifold and Zenith carb off of that engine and it has performed flawlessly with probably 7 to 10,000 miles on it. And speeds up to 100 MPH (tall gear ratio) The only hitch is starting on a warm engine, sometimes you have to crank multiple times (no starter) to get it started. Could be the design of the manifold. Zenith manual states " no Y type manifold you need a log type", and this has an aluminum Y type.
Ed aka #4

Reno Speedster · Post by **Reno Speedster** » Fri Mar 04, 2022 6:46 pm

Thanks. I have a couple Zeniths on hand. Good advice about the log style intake.

David Greenlees · Post by **David Greenlees** » Sat Mar 05, 2022 1:41 pm

Reno Speedster wrote: ↑
Fri Mar 04, 2022 6:46 pm
Thanks. I have a couple Zeniths on hand. Good advice about the log style intake.

Zenith's are very good carbs and if you have the right one I'd use it. Have worked with quite a few of them on client's cars over the years and once you get them jetted correctly they work great.

I have an aluminum Zenith with a bolt on aluminum velocity stack, no choke, and a bronze float bowl cover that the Co. made in low production runs for racing cars in the teens. Will share photos of it here in the future.

Reno Speedster · Post by **Reno Speedster** » Sat Mar 05, 2022 2:41 pm

David, any recommendations on which zenith would be the best choice?

David Greenlees · Post by **David Greenlees** » Sat Mar 05, 2022 3:01 pm

Reno Speedster wrote: ↑
Sat Mar 05, 2022 2:41 pm
David, any recommendations on which zenith would be the best choice?

Your typical model M or possibly an L ? Zenith bronze updraft carb as pictured on the #2 Car above. I don't know much about the model letters or sizes offered but typically are IE: 1 2 3 4 and larger.

They were made with various different flange and throttle orientations so with some searching you can find one that will work for your setup.

Scott_Conger · Post by **Scott_Conger** » Sat Mar 05, 2022 3:50 pm

The four considerations in setting up a Zenith of this vintage are these: Choke tube diameter, main jet, compensating jet, idle jet

The primary factor in determining any or all, is the bore and stroke of the engine. From those two known values, the 4 items listed above are selected within a specific matrix developed by Zenith. Practical considerations for our cars limit us to established choke, compensating and idle jets. The only real wildcard is the main jet, which can be fitted with an adjustable jet which avoids the guessing, fiddling and expense of manufacturing custom main jets while trying to get things to work. If it is of utmost importance to you, the choke can be messed with, too. You can increase it's size for more top end, but may wear yourself out getting it started, and it won't idle well, or you can reduce the choke size for easy starting and an idle that purrs, but top end speed will be lost. Everything is a trade off and compromise.

In most instances, probably 70% or so, the pot-metal venturi has swollen or deteriorated to some extent. When purchasing Zeniths be exceptionally wary of cast iron carbs as the swollen venturi's almost always crack them, rendering them useless. The bronze carbs will swell some and not tend to crack, but the venturi's can be a bear to get out and need to be replaced with a custom fabrication with the correct dimensions/features.

David Greenlees · Post by **David Greenlees** » Sat Mar 05, 2022 4:04 pm

Scott_Conger wrote: ↑
Sat Mar 05, 2022 3:50 pm
The four considerations in setting up a Zenith of this vintage are these: Choke tube diameter, main jet, compensating jet, idle jet

Scott, do you know of an online source for Zenith's tuning specs you mentioned before or the name of the publication?

Speedsterguy2 · Post by **Speedsterguy2** » Sat Mar 05, 2022 4:47 pm

I am interested that Ed Archer indicates he runs a Zenith L-6 on his #2 car. I have checked out a couple of L-6's, and the main throat diameter measures 1.660". I have thought that likely is too much for most Model T motors, though I also recall reading somewhere that the Indianapolis car in 1923(?) ran a pair of L-6 carbs. I have also checked out several L-5 Zeniths, which have throat diameter of 1.440", and O-4's which have throat diameter of 1.180".

Certainly it depends on an bunch of other factors as to how the particular engine breathes, but wouldn't a smaller carb be easier to manage for street use? I am intrigued with how a pair of O-4's would work on a custom manifold. I am sure they would LOOK great!

Reno Speedster · Post by **Reno Speedster** » Sat Mar 05, 2022 4:56 pm

I made a bronze venturi to replace the swollen and cracked one that came in the Zenith that I have that was built for the model T. I did my best to copy the original, but it was hard given the amount of swelling. It would be great to have some specs to follow.

I like the idea of an adjustable main jet. Do you know where they can be purchased?

Reno Speedster · Post by **Reno Speedster** » Sat Mar 05, 2022 5:01 pm

Speedsterguy2 wrote: ↑
Sat Mar 05, 2022 4:47 pm
I am interested that Ed Archer indicates he runs a Zenith L-6 on his #2 car. I have checked out a couple of L-6's, and the main throat diameter measures 1.660". I have thought that likely is too much for most Model T motors, though I also recall reading somewhere that the Indianapolis car in 1923(?) ran a pair of L-6 carbs. I have also checked out several L-5 Zeniths, which have throat diameter of 1.440", and O-4's which have throat diameter of 1.180".

Certainly it depends on an bunch of other factors as to how the particular engine breathes, but wouldn't a smaller carb be easier to manage for street use? I am intrigued with how a pair of O-4's would work on a custom manifold. I am sure they would LOOK great!

Good info. Yeah, a pair of the smaller carbs on a dual Mansfield would look awesome, but would double the adjustments. I need to measure the one I have on hand.

David Greenlees · Post by **David Greenlees** » Sat Mar 05, 2022 8:09 pm

While we are talking about Zenith's this is a very rare aluminum Zenith L6 carb on the engine in the photo. I purchased it from friend Josh Houlton in 2009 for use on a T racing engine I was planning to build with a Rajo BB head I took off a client's Mercury Speedster engine and later bought the head from him in 1986.

After quite a bit of research it was found to be a racing car carb, as it is different than bronze L's, and never had any provision for a choke or hot air tube and has its original large bolt-on velocity stack, and a 1.625" throat. There was a similar aviation version that had a choke flap and a provision for a hot air tube.

It was taken apart and inspected and cleaned and found not to need any other work. I'm now planning on using it on a racing engine in an un-restored 1913 "T" racing car. That engine has Fronty S-R head and a Fronty DOHC crankshaft.

Reno Speedster · Post by **Reno Speedster** » Sat Mar 05, 2022 8:12 pm

Here are the two I have. The one in the top with the manifold is an S4BF, which is for a T. It has a bore of 1.175. You might notice some parts are not in it. I have them all in a bag.

The one on the bottom is a 04 with a bore of 1.165. This seems a bit small. But if I could find another….

Post by **Craig Leach** » Sat Mar 05, 2022 10:56 pm

Tim I think Ed was refering to the #2 car running a L-6. If I remember correctly that car used to run twin side draft linkert Or shebler carbs with a
1 1/4" or so bore. All I know is it realy runs well.
Craig.

Post by **GGZ** » Sun Mar 06, 2022 2:11 pm

That #2 racer has always been a favorite of mine. Is it still being run?

If it were me, I would go with a barrel valve, Miller Master carburetor, probably 1 1/2" size. These were designed by THE Harry Miller. NO diecast, zinc or lead parts, NO cork parts, and everything is machined with such precision, there are NO gaskets. Everything is machined brass/bronze with the exception spray bar (Miller's version of separate jets) which is machined steel. Super simple and super powerful. The only adjustment is the rich-lean control which is controlled from a dash cable. I am currently running three of these in various sizes on Ford and Brand X brass car applications. The exhaust notes created by these carburetors are are like no other. Ed Winfield used this carburetor design for his own barrel valve carburetors which is not surprising as Winfield began working at Miller's shop when he was a teenager.

My second choice would be the aluminum barrel valve Winfields described above. Also great carburetors.

David Greenlees · Post by **David Greenlees** » Sun Mar 06, 2022 4:10 pm

An earlier carb thread worth looking at @ http://www.mtfca.com/discus/messages/17 ... 1324780912

Reno Speedster · Post by **Reno Speedster** » Sun Mar 06, 2022 9:21 pm

The Miller master is an interesting carb and from what I understand, was ahead of it’s time. But, they are rare and from the prices asked for the few I have seen for sale on line, very spendy. Something to aspire to, but probably not the first choice.

Living in Alaska, I don’t get to go to shows and look for things.