ZENITH ST4B CARB ORIGINAL RAJO C HEAD

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StanHowe
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ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Mon Sep 16, 2019 4:03 pm

Rajo 1926 4 177 Model C Ford racing head Zenith ST4B !!!!!!!!!!

Doesn't get are rarer or harder to find that this one!! And! It is in MINT original condition.

Rajo must have thought this was the best they could get if they sold it along with the C Rajo!!

This was Zenith's successor to the S4BF. They went from bronze construction with the dual ear fuel bowl level regulator to a new design using Cast Iron and a newly designed float system using a removable seat and positive shut off. Also new for this design was an accelerating venturi that was about 7/16 and fit right inside the standard venturi.

This one appears to have virtually no use. The only signs of ever having been used are the lower plugs have been out a bunch of times, probably at least a few times with a pair of pliers. This would have come jetted for the Rajo C but most likely included several slightly smaller and slightly larger jets for tuning the RAJO at the track. Hence, the plugs having been out a bunch. (While I could supply a handful of various sized jets I prefer to replace the standard jet system with my adjustable jet which makes it very easy to dial in the mixture instead of changing jets)

It is actually only slightly larger than an S4BF, the inlet and throat are about the same. The Venturi opening is a little larger. It will get a new Venturi when it goes down the road, same size as the factory one.

Nice thing about this is that even tho it is a racing carb it has a fairly standard choke setup for starting and cold running which also makes it pretty suitable for your daily driving that needs a little waking up and also has an idle mixture adjustment which not all racing carbs have. It should be a great carburetor for any kind of T running and driving whether you have an overhead and a hot cam or just like a good running T!

At this point I have not run this, it is not done and good to go, I got it with a pile of carbs I bought and spent Saturday night cleaning it up and mounting it on this cool manifold. I usually don't work Saturday night but I wanted to see it all cleaned up and mounted on this manifold.

It is for sale, delivery in October, buy it with the manifold shown - $1000; without the manifold $850. I can either leave it cast color or powder coat it black, your choice, no extra charge. You can leave the levers and plugs bronze or I'll powder coat them. You just let me know.

Paypal preferred, please do not respond through the MTFCA relay, call or text 406 949 3448 or email at stanhowemt@aol.com

Go RACE!!!!
2019 9 16 zenith 006.JPG
2019 9 16 zenith 007.JPG
2019 9 16 zenith 008.JPG
2019 9 16 zenith 009.JPG
2019 9 16 zenith 004.JPG


DustySpokes
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by DustySpokes » Mon Sep 16, 2019 7:27 pm

Stan, once again you are Bang-On the Money knowledge wise ! I have a C-35 8 valve head that I bought many years ago. I spent many years researching and finding out what the correct 2 carbs were that RAJO offered with the C-35 head! One was a Schebler 1-1/4 inch updraft and the other is the Zenith ST4B. I have some lovely Scheblers but like the looks of the Zenith better. This carb is indeed a tough one to find.


Topic author
StanHowe
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Mon Sep 16, 2019 9:32 pm

Thanks, Ed. It is the only one I have ever found in all the hundreds and hundreds of carbs I've gone through. I thought it had to be pretty special and it is. Whether that will translate into any money remains to be seen.


Topic author
StanHowe
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Wed Sep 18, 2019 6:56 pm

Little more explanation. This would originally mount to the RAJO C manifold directly. So this manifold is not needed.
To mount it to a stock T motor you would need a manifold with the correct bolt flange.
So I mounted it to this manifold so you could see how it would look. You could mount it to a stock Zenith S4BF manifold so some other accessory manifold as long as the flange is correct.


noelchico
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by noelchico » Thu Sep 19, 2019 11:20 am

Stan, I have a RAJO C-35 head and manifold I got from Mark Chaffin several years ago and am very interested in this carb except that it appears that the manifold carb mounting is 90 degrees rotated from what appears correct for this carb. This would put the carb crossways to the manifold rather than in line with it. Would I need an additional piece. I therefore question if this is the correct carb for this manifold
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Dropacent
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by Dropacent » Thu Sep 19, 2019 11:55 am

One of these may do the trick, Noel. The left one rotates to any degree. Tmorsher@icloud.com if I can help
4EECCAF7-ED2D-4A3F-BD74-010B462D606A.jpeg
E0FEEB41-2C36-4186-9858-501D2A5C3CD5.jpeg


Topic author
StanHowe
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Thu Sep 19, 2019 3:13 pm

I think from what I was told the other day from a guy who has several RAJO C heads is that the flange orientation is correct for the racing intake manifold but depending on which of the combination intake and exhaust manifolds you have for the RAJO C -- not for racing, it is possible you would need the 90 degree flange adapter.

I've heard from several people that have never seen one of these but believe it is the one listed in the original RAJO catalog for the head.

This is the kit listing from Carb Junky, who I have found to be the most accurate information available quickly on the Internet:

Rajo Applications and kits
Make Year Engine Model | - - - - - - - - - - - - Carburetor - - - Kit

Rajo 1925 4 Ford T racing head Stromberg OX-2 1542
Rajo 1926 4 Racing cylinder head Schebler S 204 1683
Rajo 1926 4 177 Model B Ford racing head Zenith U6 4003 1671
Rajo 1926 4 177 Model C Ford racing head Zenith ST4B 3945 2970

Note that the flange orientation is the same on the OX-2 which is listed for the standard head, the Zenith U6 has (without going out to the shop to look) 90 degree orientation from the ST4B and the OX-2.

My thinking is that it probably came with an adapter like the one Tim shows or a similar one for mounting on the standard manifold. Those adapters are very common, I sell quite a few of them so people can mount various carbs on different manifolds. I may or may not have one that fits this Zenith.

The adapters came in a variety of designs with many different "drops" available as well as many different flange sizes.


Topic author
StanHowe
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Thu Sep 19, 2019 3:15 pm

2019 9 19 flange adapter.jpeg
By the way, thanks Tim.


Topic author
StanHowe
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Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Thu Sep 19, 2019 3:29 pm

This is the ad for the original RAJO C head.
2019 9 19 rajo ad.jpg


Topic author
StanHowe
Posts: 310
Joined: Mon Jan 07, 2019 5:42 pm
First Name: Stan
Last Name: Howe
Location: Helena, MT
Board Member Since: 1999

Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Thu Sep 19, 2019 3:30 pm

Pretty grainy but I believe it shows the ST4B mounted directly on the manifold.


Topic author
StanHowe
Posts: 310
Joined: Mon Jan 07, 2019 5:42 pm
First Name: Stan
Last Name: Howe
Location: Helena, MT
Board Member Since: 1999

Re: ZENITH ST4B CARB ORIGINAL RAJO C HEAD

Post by StanHowe » Thu Sep 19, 2019 6:32 pm

Carburetor is sold.
Thanks to MTFCA and the members who support it.

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