Seeking Opinions of High Compression and OHV owners

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Model T Ford Forum: Forum 2016: Seeking Opinions of High Compression and OHV owners
Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, January 11, 2016 - 12:17 pm:

Everyone has heard that fordor sedans are the heaviest T body style. I use my 26 fordor for a driver and on short tours. It has .040 over aluminum flat top pistons, counterbalanced crank, ,280 Stipe cam, 12 volt pointless distributor ignition, Model B intake and exhaust manifolds and B Zenith carb.

Currently, I have an iron Simmons Hi Power head on it. I have immediate access and availability to a stock high head, a Waukeshaw Ricardo head, a 'Z' head, and a repo Rajo 4 valve head, made in Australia years ago. The Rajo has huge 1.94" Chevy SB intake valves. Chaffin's recommends that a stock cam be used with Rajo heads and I can swap the Stipe back for a stock cam. A knowledgeable T engine rebuilder told me that a Rajo 4 valve isn't much, if any, faster than a 'Z' head, but that it will get you to full power, a lot faster.

Knowing all this (high compression and OHV head owners), what would be your choice for maximum streetable and touring power? The only other option would be to sell some parts and buy a Pruis head if it would be any better. I know this post may seem like a duplication of other recent similar posts, but the other discussions don't consider all the options that I have at hand.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Jerry VanOoteghem - SE Michigan on Monday, January 11, 2016 - 12:24 pm:

Aside from "touring power", the biggest WOW factor is the Rajo for sure.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Constantine in Australia on Monday, January 11, 2016 - 01:09 pm:

What's wrong with the Simmons head that's on the car now? I would not change that for either a P or Z head. If anything, perhaps you could mill the Simmons for more compression? Does your Fordor really need a Rajo since you only use the car "for a driver and on short tours"?

Maybe look elsewhere...do you have a 11 or 10 tooth? A Ruckstell or Warford?

I'll buy the Simmons from you if you decide you don't want it.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, January 11, 2016 - 01:39 pm:

Constantine, I failed to mention that it has a Ruxtell and 3.63 gears and it driven mostly on flat and, rarely, hilly terrain. Nothing is "wrong" with the Simmons Super power head on the car, now. I never have seen the advertised or actual compression ratio for a Simmons head, but it doesn't look to be any more than a "Z", or Pruis head, if even that much. It, like the Waukesha and other aftermarket heads does have more cooling capacity. Personally, since the car isn't judged, I just want power if I need it; not that that is a frequent thing. I'm not going to be racing any speedsters.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Walt Berdan, Bellevue, WA on Monday, January 11, 2016 - 01:54 pm:

The 4 valve Rajo is a nice head for this type of application. I ran one on my speedster for several years and it worked just fine. My motor had a T crank, distributor, and a Stipe 280 cam along with Model A intake, exhaust and carburetor. I'm not sure why Chaffins recommends the stock cam for this combination, I was certainly happy with the higher lift and different profile from the Stipe 280. Possibly they feel the bottom end torque is better from the stock profile when in a heavy car. I currently use a Stipe 280 with a Fronty in my speedster but it's a very different application.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, January 11, 2016 - 02:05 pm:

Walt, they explained to me that with the additional lift created by the rocker arm ratio, that a higher lift cam was not necessary.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Monday, January 11, 2016 - 02:14 pm:

The Simmons, Haibe and Giant power heads from back in the day has almost identical combustion chambers and it seems like the Z head is a copy of one of them. The Tulsa Model T club has done some measuring and determined the compression to just about 4.3:1 for one of those old iron heads, while the modern Z and Prus can go a little higher (to 5:1) since we have better gas nowadays.

http://mtfctulsa.com/Tech/head_design.htm

There are differences between old and new 4v Rajos too - I think the old ones had 1:1 rockers, while the modern repros may have 1:1.5? Thus an old head may take more cam lift than a modern, too much lift with 1:1.5 may break something?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Constantine in Australia on Monday, January 11, 2016 - 02:24 pm:

Terry, one option could be changing to a 10 tooth and either milling the Simmons for more compression or replacing it with a alloy Z or P head. The P head would look correct on your 26.

IMHO adding a Rajo for your stated needs is overkill plus more power tends to lead to more speed. Stopping a Fordor in an emergency while cruising at 50mph would "interesting". Adding a overdrive KC Warford (and using a 10 tooth) would be a better option than a Rajo since you drive on mainly flat roads.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, January 11, 2016 - 03:15 pm:

Constantine, The Ruxtell in my fordor had a 10 tooth pinion when I got it. I had it rebuilt with an 11 tooth to get just a little more speed and less stress on the engine. If I added a Warford, I'd have driveshaft shortening to do. I don't want to go there.

I have a new in the box Z head. Getting a new Pruis head, wouldn't be a problem. The car is equipped with Texas T hydraulic rear disc brakes, so I don't worry about stopping, plus I am a cautious driver, I don't tailgate. As Jerry and Walt said above, the Rajo would add to the WOW factor. The setup is very sweet looking with polished aluminum valve covers on the head and one for the side of the block.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Monday, January 11, 2016 - 03:48 pm:

Eventually I'll get my hands a 4 valve Rajo for my speedster. The head will be black and I'll have the valve covers brass plated to match the rest of the car. I want to get another Zenith S4BF to match the one I already have and run those as a pair. I think those carbs will look pretty sweet hanging out the side.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Constantine in Australia on Monday, January 11, 2016 - 06:19 pm:

Terry, fair enough, as they say there's more than one way to skin a cat. If your car already has disc brakes and you have a Rajo sitting on a shelf in your garage, it makes sense to go that way. It certainly will give the car a huge WOW factor, especially being a Fordor.

I don't the answer to this, but you might want to look into the weight difference between your Rajo including rockers etc. and a alloy P head...and what this difference will mean for handling on an already heavy car.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Monday, January 11, 2016 - 07:25 pm:

Constantine, The Rajo is heavy; so much so that it is a strain for me to lift it, Maybe I'll change the front spring out with a TT front spring or just add a leaf to the existing spring. Ha.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Eric Hylen- Central Minnesota on Tuesday, January 12, 2016 - 09:08 am:

Sounds like it's time to box the frame and drop a small block Chevy in it. :-)


Top of pagePrevious messageNext messageBottom of page Link to this message  By Norman T. Kling on Tuesday, January 12, 2016 - 09:19 am:

If you do anything like this to your car, be sure to put brakes on the wheels. The increased speed will require more stopping power, and the possibility of breaking something between the U joint and the wheels increase. If you do break the drivetrain, you will have ONLY the wheel brakes to stop you.
Norm


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Tuesday, January 12, 2016 - 12:30 pm:

Thanks everyone, the Rajo installation is intriguing. If I do so, I already have rear disk brakes, and I am not just 'hopping up' the motor to race speedsters, with. I think I drive my t sensibly enough to stay out of trouble.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Tuesday, January 12, 2016 - 05:58 pm:

I uh, *cough cough* I think the Rajo sounds super lame and you should just sell it and be rid of that silly thing. =P


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Tuesday, January 12, 2016 - 08:32 pm:

Seth, if a 4 valve Rajo, (which I know is on your Christmas gift list) is "lame", then all other heads: Pruis, Z, Sherman, Simmons, Ricaro, ETC, must be plain DEAD. If you quit getting those lumps of coal for Christmas, maybe one would appear some day.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Barrett in Auburn Ca. on Tuesday, January 12, 2016 - 10:11 pm:

Terry, a few thoughts on the 4 valve Rajo. It is a model "A" head. The model of the head, not the car. They will run well but have some drawbacks. One of the good things is they can be installed on 26-27 cars without notching the gas tank. I don't think that is an issue with your 4 door anyway.
In 2000 I bought a 26 Tudor on the net and drove it home from Seattle 1000 miles in five days. Had a four valve Rajo with model A Ford intake and exhaust manifolds. When we had to get on the freeway, It would roll at better than 60 in Warford overdrive. Conversation in the car was nearly impossible at that point. So from personal experience I can tell you that these heads will run in a heavy car. (There were three big guys and all our luggage in the car on our trip. We flew up there on one way tickets.) The four valve Rajo is low compression and benefits from high compression pistons. Also, there is an inherent weakness in the rocker arm mounting that is fairly easily corrected by using one shaft instead of two, but this means the covers must be slotted if you have them. Also, some of the repro composition head gaskets have no fire ring and are prone to failure. Maybe a real copper gasket is available now.
All this being said, a well built flathead will keep up with most any overhead up till maybe 40 or 50 MPH, when the more efficient and higher compression overheads begin to really breathe. The reliability and simplicity of the flathead counts for a lot, but overheads just look bitchin'. Pardon the language, but that's just how it is.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Erik Barrett in Auburn Ca. on Tuesday, January 12, 2016 - 10:13 pm:

My comments pertained to the original heads, it is likely that the Aussie repros may have had some improvements.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Terry Woods, Richmond, Texas on Tuesday, January 12, 2016 - 11:13 pm:

Erik, It is one of the Australian made reproductions made in the late eighties or early nineties. It has two separate valve covers with two separate rocker arm shafts, so I might have to change that. The thing that amazes me is the huge 1.94" valves. I wish this engines block was ported and had 1,543 Ford Windsor valves in the exhaust.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Seth in Alabama on Tuesday, January 12, 2016 - 11:36 pm:

Lol Terry, apparently I just need to be a better boy this year.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Les VonNordheim on Wednesday, January 13, 2016 - 12:39 am:

Terry,
I tried an Australia reproduction aluminum RAJO 4 valve head on my model T and had problems with blowing head gaskets. I also did not like how several of the rockers lined up with the valve stems. There was less than half the valve stem under two rockers. Also, took a lot of grinding to get inside rocker arm clearance in the Repro aluminum valve covers. Rockers depend on oil soaked felts to provide lube. The head came with an aluminum intake manifold which was larger than a model A or B.
Have been using a Giant power head for the last 10 years. The Giant head performs better compared to a low head milled .060". Have not tried milling the Giant head for more compression. I also have a Z head and have not tried it.
It would be interesting to CC a Z and Giant head for comparison. The Giant head is cast iron vice aluminum which I like better....less corrosion.

My 2 cents.


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