MTFCA Forum

Will a Roof exhaust manifold interchange or work on a Rajo head?

I have what I'm told is a Rajo head but the exhaust manifold has Roof cast in it. Yes it does fit and bolt on to the head I have.
thnx
brasscarguy

Do you have a picture. I have a 2 rajo exhaust manifolds

Sumptin does not sound right , but post a few pictures of the manifold and the head.

I believe the Liberty 8 is the only Roof exhaust manifold that had “ROOF” markings.
The 2 intake port head had a very similar exhaust manifold to a Fronty T/S, but had different bolt spacing and no “ROOF” markings
The 16 valve stuff was waaaay different and couldn’t possibly interchange with any other heads.

All the RAJO heads I can think of;
4 valve —> no exhaust ports
Model 30 (commercial) —> 4 exhaust ports right side
Model C35 —> 3 exhaust ports right side
Model B/BB —> 4 exhaust ports left side

The C35 would be the closest interchange, but the RAJO center exhaust port is a large oval shape and is no doubt much larger than either of the Roof manifold center flanges. The head would have to have been drilled for the Roof bolts as well. However… the C35 also had 2 intake ports on the right side that the Liberty 8 exhaust manifold would have completely obstructed. Could it be a 2 port manifold with markings…? I’m with Dan, need some pics…

I have a roof liberty, maybe the manifold fits?

here are a few pictures of questioned head, as you can see the valve cover says Frontenac, which fits the head perfect, the exhaust manifold says Roof 8, and fits the head perfect, but the head is supposedly a Rajo, so what is the correct item manufacture. I really need a rocker arm for this engine and am having a bit of a issue determining what it really is.

Your overhead is not a Rajo. I believe it is a two port 8 valve Roof head , but I don’t know what model name Roof used for it. The valve rockers you show may or may not be Roof rockers, but if they are Roof it will be very hard to find replacements. You may have to replace all 8 rockers and make new rocker stands. I looks like it is a nice running head.

Definitely a Roof 2 port, same as I have pictured above. The 1/8” pipe plugs above the intake ports and the 3 freeze plugs in the top are dead giveaways. That is an interesting variation of the exhaust manifold as it has the Roof name cast in.

The head that I have pictured above was acquired after many years of searching… only to find that the casting design is poor at best. My advice is to run a good water pump (not just a typical circulator) and keep the power output fairly low. Heat buildup will be its ruin! There is no water between the port floors and combustion chamber, just a thin web of iron that is too thin to take a valve insert. Rebuilding will take some creativity. Also, ditch those exhaust gaskets! Get some high temp silicone and prevent the ear breakage that is sure to come

Yes, definitely a Roof head with a Fronty cover. Good running head with a little added compression. Unfortunately as Kevin mentions above the port / chamber roof design is not very robust and really the only way to salvage a head with bad seats is welding.
Here is a picture of the correct rocker arm cover and the Roof rocker assembly.

Is that a 1:1 rocker ratio Dan?

Andy

good to find out what this thing really is. as for the rocker arms they seem to be not 1:1 but, maybe these are not the right ones.

1.2 isn’t much rocker arm ratio. Makes choosing a cam easier, you don’t have to account for much extra at the valve.

Andy

Here is a photo from the Bill Smith collection of a Roof 8 valve head converted to overhead cam. The front and rear of the head has had holes drilled and plugged for water passages.