I am at the stage of starting to get all my ducks in a row for the speedster project engine. I am really considering using a Rajo. I think I understand the different models, correct me if Im wrong on any of this: Model A has four valves in head, 2 valve covers, intake on passenger side and exhaust on driver side. Model B has one valve cover 8 valves in head, intake on passenger side and exhaust on driver side. Model C has 8 valves in head, one valve cover, intake and exhaust on passenger side and came with a combination intake/exhaust manifold. Then the Chaffin head has 8 valves in head, intake on passenger side and exhaust on driver side. and one valve cover. It has the Hi-rise intake manifold. Some of my questions are, does the Chaffin head have another intake option. I will be contacting them soon, but maybe someone knows if there is a "more standard" style intake. My Speedster has a low steel firewall in the stock Ford location. Will any of the heads or valve covers hit the firewall. I do not want to modify my firewall. I will be running a basically stock engine, with a 250 or 280 cam (I can go either way) It will have a DU-4 mag setup on the driver side of the engine. Will there be anyway to keep the exhaust under the hood with the exhaust on the driver side. Im not totally against using a side pipe, but the style of car Im trying to build has a full hood. I have not chosen the carb yet, but was leaning toward a U&J single carb or a Stromberg OF.. I am not after speed. I want it as reliable as possible and enough power for the Arkansas Ozark Mountains. and the "WOW look at that" factor.... The only other thing is that I also plan on using one of my "Chicago" auxillary transmissions. My budget will barely handle a new Chaffin head (it will hurt and I will just have to sell more stuff, and everyone will have to listen to me whine about it ) but Im more about being period correct and reliable ... Any input is appreciated ...
Don't know OHV heads at all, but seems an exhaust on the driver's side (steering column) would have to exit out the hood for clearance.
The 1923 ad for the Model A RAJO seems neat, stock exhaust manifold, and opportunity to add nifty intake with a big carb.
The ad states this one can add 8hp-14hp to the Ford, that is nice.
Donnie I think they will all hit the firewall. I know your using a mag so coil box is not an issue. Valve covers interfere with coil boxes mounted on the firewall. I would guess that applies to Mark Chaffins head also. Maybe he will see this and chime in.
Did everybody who used a Rajo "in the day" need to use distributor or external magneto? I'd like to put together an engine with my C-35 head. I'd like to run either stock magneto and coils or possibly (gasp) an e-timer or similar system for more timer variability if needed. I also don't really want to have to cut the firewall on the 26 unless necessary.
Model A (4-valve) would be your best bet to clear the firewall. I believe they will clear most if not all original T firewalls.
Intake and exhaust are both on passenger side. Intake valves are in the head, exhaust valves are in the block in their stock location, and uses the stock exhaust ports in the block as well.
Donnie, check out the pics here for how you can do driver's side exhaust without using side pipes.
Donnie, Because the 4 valve F head uses the exhaust valves in the block, I'm going to have to rethink my throttle linkage if the intake is on the driver's side. I haven't set the head on a block, but I wasn't aware that the intake and exhaust weren't on the same side!
As for cam selection, when you talk to Mark Chaffin, he more than likely will tell you the same thing that he told me; that he recommends a stock .250 lift cam because of the additional lift that you get from the rocker arm ratio. He recommends this, regardless of Rajo head. Of course, if you were running a 4 valve F head like me, you could always have a stock cam custom reground with .250 lift on the intakes and .280 lift on the exhaust.
Terry the intake and exhaust for the 4 valve F head are on the passenger side.
Seth, your link shows a BB head and the firewall is cut out. I see the exhaust can be made to work under a hood. Im hoping that the firewall does not need to be cut. If it does I probably will not use a Rajo. It seems strange that if the Rajos were marketed to the general car market, that such a major modification to the firewall was needed ... ??? Terry I could be wrong about the A head ... and the intake/ exhaust locations. I am very far from anyone who knows anything about Rajo heads.
Noel it's the valve cover that gets in the way of the coil box. RAJO had a valve cover that the back was open. It was not a straight cut on the back( actually cast). I have an early cover somewhere but haven't seen it for a while.
I think the Rajo model A will clear the metal firewall, but in my experience interferes with the wood firewall. The model As I have seen have the rear of the valve cover open. It is all very close.
(Message edited by Tony_bowker on January 17, 2016)
There are two Rajo heads that will clear a stock firewall. The 4 valve will clear all firewalls because the back of the head is pretty much the same height as a stock head. The two piece valve covers you see most of the time on a 4 valve are not the original cover. As Tony stated, the original 4 valve cover was a one piece flat cover ( almost the same shape as the 8 valve covers) except the back was open to clear the firewall and the top rear surface had notches in it to provide clearance around the lower porcelain insulators on the coil box. Of the 8 valve heads, the later B heads had a flat slope back that was implemented to provide clearance when used on an improved car. In my experience, these heads are pretty rare.
Dan M , So it sounds to me like the A head with either the stock open back valve cover or using the 2 individual valve covers, may be my only choice. Is the only interference with the other heads the coil porcelains or is the steel firewall in the way also. I will not have coils, but I do not want to cut my firewall. My car has a low steel firewall and is not an Improved firewall. Thanks for all the input ..
Here are a couple pictures of my firewall. It will clear a stock head very well. Even the indent I made for the steering column lowering block leaves a lot of clearance to the side of a stock head. I do not mind trimming something, but I do not want to cut out the entire coil box area. Thanks again ...
Donnie, Why not plug the insulator holes in your firewall and use a 26-27 engine mounted coil box?
He's gonna use a Bosch DU-4 mag. I think he mainly just doesn't want to cut the firewall.
Donnie you could always move the firewall back - but you may have too much of the body completed to feel like fooling with that. I think the easiest thing I've heard of is using the frame-to-firewall brackets and just putting the front hole on the bracket in the rear hole on the frame, then drilling a new rear hole.
Donnie, One of the big selling points of the RAJO "A" head was with the original one piece valve cover, they were the only overhead that could be put in without changing the firewall, as depicted in Dan Treace's advertisement.
Both intake and exhaust are on the passenger side as Seth mentioned and this is one Helluva OHV Head. You must be using a cross drive for your Mag, and if so your Mag will be close to the end of your steering column so your advance and retard spark will be quite easy to rig. I have some extra Valve Covers made that even allow the coil box to stay in the firewall. Good Luck, Bill
Seth, I am too far along to change any of the body layout. Moving the body will also change all my steering geometry, that I like to never got right. I guess Ill start looking for a Rajo Model A head. I like the looks of the two separate valve covers, or the stock single cover will be OK if that is what I can find. The intake and exhaust on the same side also fits my car well. I was thinking the intake and exhaust were on opposite sides on the A head. I was looking at a photo that I thought showed the exhaust on the right side. But looking closely I guess the holes were the spark plug holes ... my mistake Are the two separate valve covers still available for the A head, or are they some more of the unobtanium type of item ... I had always planned on using some type of aftermarket flat head. I have several to choose from, but Im having a urge for a Rajo... as I get closer to time to do the engine ... Is there some form of medicine I can take to lessen those urges ... or am I doomed ... Thanks again for all the help...
Pictures of an Australian built, Speedway Engineering Rajo Model A four valve head. Because the head is cast slightly different than an original head,; it requires the special twin valve covers. A repo single valve cover could be modified to fit, but would allow any excess oil from the felt pads over the rocker arms, to leak, creating a mess.
These photos were furnished by the Gent that I bought the setup from. Because of their poor quality, they don't do the setup justice. In reality, its pretty than a Red Headed Woodpecker.
I installed a B RAJO in my T. It would not clear the wood or metal firewall. I found a low radiator metal firewall that was easily modified by a local sheet metal shop. They welded in a 2 inch deep box in the area used by the old coil box - the area defined by the two outside vertical beads and below the horizontal one. It looks like the cars was made that way - no one had ever noticed it! From the inside it looks like a coil box.