MTFCA Forum

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I decided to CC my head today. Even though I used a very primitive procedure, the doctors said Ill be OK (or at least as OK as I ever was)

I have heard that the Rajo 4 valve heads are the same CC or compression ratio as a stock head. But to my eye it just looked to be larger. So to ease my mind I did an old school CC test. I leveled the head, put in the spark plug and filled it as full as I could get it with water from a large syringe marked in CC measurements. The Rajo measured to be 295 CCs and then the stock model T head measured to be 315 CCs. In reality I probably have an error factor of at least 20 CCs so I guess the Rajo and Stock head are the same. I also took some pics of the Rajo intake valve compared to a stock model T intake valve.... A huge difference !!! The old girl should be able to breathe very good ...

have fun and be safe ......

If you take a piece of 1/4" think acrylic big enough to cover the chamber and drill a 1/4" hole in it and glue the plate to the head with some grease you can a fill the chamber thru the hole and get a much more accurate measurement. You might be surprised at the difference in readings if you redo the measurement.

Dan, that is a very good idea. Ill have to remember to do that next time. For my purposes, my test is OK. But I could see where the clear cover would give a very accurate measurement. I know some racers want all the chambers to be exactly the same size. I was just interested in knowing that the Rajo was about the same as a stock head and not larger. Im just building this engine for "bling", its more "show" than "go". Staying close to stock compression is OK with me.

The model A Rajo head can really run. "A" is the model designation of the head, not the car it goes on. These heads benefit from high compression pistons with the domed head. Also, the rocker arm shafts should be replaced with a single piece unit that goes through both rocker assemblies. These heads have a weakness in the area where the rocker towers bolt down, that being the bolts are at right angles to the shaft centerline, so the towers are stressed side to side every time the valves are pushed open. A single rocker arm shaft helps to stabilize the whole thing. I had to repair cracks and mangled rocker arm bolt holes in my four valve head. Watch one of these run and you can see the rocker towers flexing. If you have the rocker cover it will have to be slotted. One cool thing about these heads is any intake manifold for model A's is easy to put on so you have lots of possibilities there.

Eric, Was your head an aluminum head or a cast iron head.? My 4 valve head is cast iron. I have wondered if the rocker tower problem is worse on an aluminum head than it is on a cast iron head. I am planning on the single rocker shaft, but I plan on seeing how it acts with two shafts at first. Im not going to use domed head pistons as Im not trying to build a zoom zoom car. The big issue I have right now is trying to get me a set of push rods made. I can not use the pushrods that came with my 4 valve head. Someone installed 292/312 Y-Block lifters in my engine sometime in the past. So I need solid .312 diameter push rods, 10.531 long, and threaded 5/16 NF on top and also have a radius to fit the Y-Block lifter radius at the bottom. I could have my engines lifter bosses sleeved back to stock and then use adjustable lifters, but since my y-block lifters are in like new condition, I hate to go to all the trouble to have the machine work done. When 4 push rods would solve the problem. The "big" push rod manufacturing guys have said they can do it, but I never hear back from them. So far I have been dealing with Manton push rods, and Smith Brothers pushrods with no results yet. ..... Anyone know of someone who could make me four custom pushrods . ??? That is the last thing I need, before I can start to assemble this engine ...

The Y-block lifters are really the best choice for overheads. We have had pushrods made for the Wild Cherry racer. I will look up who did them for us and let you know. My Rajo 4 valve was original cast iron.

Erick, any help finding someone to make the pushrods will be greatly appreciated. I agree that the y-block lifters are great and a very good idea for the overheads. That is why Im not wanting to change them out. Its also good to know that you had the rocker towers flex problem with the cast iron head. I will be adding the one piece rocker shaft.

Regarding the making of pushrods.....I've made many over the years (for various engines) from unhardened drill rod. The rod can be obtained from any good steel supply store and is available in all the standard fractional sizes and in three foot lengths. Unless they have to be drilled for oil, they make very good replacements as they're made from good quality, tough steel.

Admittedly this might not be the answer for your situation, but drill rod is also great for various pins, control rods, etc.

Donnie, I think your Drs are a bit off.

We need more info on why they think your OK.

You have a mess of Model T’s and are talking about cubic centimeters.
Something has to be wrong.
Please get a second opinion before making any important decisions.
FYI purchasing another Model T is a natural act and is not an important decision

Donnie, Keep us posted. I love your project!

Dobro, see the thread on overhead parts. That's who made our pushrods.

The doctors said I was as good as I ever was... So that leaves a lot of room as to what being OK means.

John, The engine build is going very slowly, but as soon as I get a running engine the speedster project is almost done . Ill try to post some pictures soon.

I did get to talk to Smith Brothers pushrods today. No price estimate yet, but he did say they can build them and should take about two to three weeks, due to them sending them out to be hardened.

As to me doing a "speedster project update" like I used to do, The new forum is playing havock with me doing a long post. Five pictures per post as well as the pics posting in "reverse" order, is really messing with my posting ability.

In the past I have copied and posted entire sales catalogs, sometimes posting as many as 75 pictures in one post. By doing it that way the catalog was one continues string that viewed very well. I see no way of posting entire catalogs, or posting long progress updates.

I like lots of new things on the forum, but some things "not so much"

have fun and be safe ...

Donnie,
I never attempted to share much on my project until the new forum. I on the other hand, I was having trouble posting any of my photos because of having to re-size them. I was able to do it but, it wasn't handy. I never tried to post a string of photos as you have,( and I was impressed how you made it happen )but now I can drop the photos in and it works. Maybe Chris can make it possible to string again? Reading about your build has been so interesting , it inspired me to share my project (some what OT but still should have been interesting to at least some). Looking forward to the final phase of your project, and some day I hope to see it. Thanks again for sharing the build.

John, I will continue posting some updates as I progress on the speedster project. I'm still in the learning stage of the "new forum" Its funny how some folks had so much trouble posting pictures on the old forum, but the new forum picture posting is easy for them. But now Im having problems posting on the new forum. I once posted 153 photos in one single post. For me its easier to convey a build or thought process with a string of photos that I have pre sorted to the right order, than it is to post the same pictures 5 at a time (and in the reverse order of what I need). The new 5 picture limit and backward order is really "cramping my style" But Ill struggle thru it and I may even find myself a "new style"

have fun and be safe ....