Rajo head ID

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Shelbycsx
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Rajo head ID

Post by Shelbycsx » Tue Oct 27, 2020 3:35 pm

I believe this is the BB head. It has eight 18mm plugs no 1/2 threads and a slanted casting by the firewall. The serial number is in the 12000 range.
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Mark Chaffin
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Re: Rajo head ID

Post by Mark Chaffin » Tue Oct 27, 2020 3:50 pm

Yes. Appears to be a late production BB. Someone likely drilled and tapped the head for the second set of plugs as that model head did not come equipped for dual plug. Only the BBR. Nice looking head though.


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Shelbycsx
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Re: Rajo head ID

Post by Shelbycsx » Tue Oct 27, 2020 9:07 pm

What year did rajo stop making heads?

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Mark Gregush
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Re: Rajo head ID

Post by Mark Gregush » Tue Oct 27, 2020 10:14 pm

I know the voices aren't real but damn they have some good ideas! :shock:

1921 Huckster
1925 Cut down pickup

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doodlebugt
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Re: Rajo head ID

Post by doodlebugt » Wed Oct 28, 2020 4:50 am

My BB is similar. It is set up for 8 x 18mm plugs.
It also has the blanking plate on the heater crossover.
I had a repro exhaust manifold and original down pipe, but the exit goes through plug 3.
Bruce
Bruce Csorba
Melbourne, Australia

15 4-spring Rajo racer
17 C-cab van
25 "Dalgety" Tourer


elliott1936
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Re: Rajo head ID

Post by elliott1936 » Wed Oct 28, 2020 1:11 pm

I don't think the head is a BB. It has one set of spark plugs on the exhaust side. This head is the same as mine. I have the same exhaust manifold and I have the intake manifold also which is a unit that has port that connects with the middle inlet for the heat riser. My head is a B Rajo. Tom


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Shelbycsx
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Re: Rajo head ID

Post by Shelbycsx » Wed Oct 28, 2020 2:34 pm

It has eight plugs 18mm you just can't see them in the photo, B's had 1/2 pipe thread. Does yours have the slanted casting by the fire wall.

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Mark Chaffin
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Re: Rajo head ID

Post by Mark Chaffin » Wed Oct 28, 2020 10:07 pm

All Model BB heads have the heating duct between the two intake ports. It was a fuel economy / intake manifold heating feature. The cylinder depth was 1 1/8. They came drilled for one set of plugs on the intake side.

The Model BBR had dual plug capability. 1 inch cylinder depth. No heating port between the intake ports. The rocker assembly was also set up with roller bearings for the rocker arms.

Some BB heads were drilled and tapped for the other set of plugs on the exhaust side and milled by their owner's to increase performance; however, they did not come from the factory that way.

The first cross flow head (Model 31) had a single set of plugs on an angle on the exhaust side only and did not have the recessed plug ports on the intake side. It also did not have the heating port between the intake ports. The Model 31 was produced around 1920 and was used by Knowl Bullock to win the Pike's Peak Hill Climb. The Model 31 is also referred to as the Model B by those that don't know any better.

The Model 30 Commercial Head or "Truck" head. Had four intake ports and one intake port all on the same side (passenger side) and one set of plugs. The rocker arms were stamped and not forged steel. The rocker towers were held in place by one bolt and not two like the Model 31, BB and BBR cylinder heads. This head is the least desirable of all the RAJO cylinder heads.

Lastly, the Model C35 cylinder head had three exhaust ports and two intake ports all on the same side (passenger side) and one set of plugs on the driver's side. I have seen them with 1:1 stamped rocker arms and 1.5:1 forged rocker arms. The rocker towers were held in place by one bolt and not two like the Model 31, BB and BBR. This was the last head designed by Joe for the Model T engine.

In 1926, Joe modified the patterns for the Model BB and BBR to causing a relief at the rear of the cylinder head to allow it to be used on the "improved Ford". This relief was added to clear the gas tank mounted in the cowl.

Hope this helps shed some light on the subject. :)


Topic author
Shelbycsx
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Re: Rajo head ID

Post by Shelbycsx » Wed Oct 28, 2020 10:51 pm

Thanks Mark. I would be interested in buying an ori intake manifold if anyone has one.

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