Going thru some Model T and A parts that I am selling. I have a bucket of intakes (10-12), so I started looking to see if I had the holly grail, the first cast iron type after aluminum, no I didn't. What I did observe is that there are a heck of lot of differences in their construction. Some are more straight through at the carb mount some are more tapered (funnel like), some have a bit more volume in the manifold to block area. Some are thicker by almost an 1/8" from the face out to pad (they seem to be the ones with larger passage at bend to block). I picked out 3 that might have larger internal passages. When I checked those one weighed over 3oz less then the others. (2 13.X oz, 2 13.X oz and 2 10.X oz) If this make sense, some have a more tapered top inside where they turn to enter the block and some are more rounded.
Some have the casting buttons some don't. The ones with the buttons generally seem larger inside. All kinds of different casting marks.
Would have to do a CC volume check to see if they are really any larger inside.
And one of them (off my touring) has a petcock stuck in the side. Wonder what that's for.
Let more air out! Bet it had a wolf whistle at one time, or priming cup or vacuum wiper and the petcock is just plugging the hole.
Many of the ones I have had small holes drilled in them, about 3/16" dia. I think they may have been for press in vacuum wiper hose fittings. This includes a what looks to be NOS manifold. The small hole may have been a way to take them out of service. ?
I believe that for the most part the petcock in the manifold was an auxiliary air valve. Kits were sold to control them from the dash, too.
I noticed the differences over the years of the intake manifolds also. Always have a lot of them at swap meets it seems like.
Maybe Ford had different manufactures make them. Some have Ford script and some don't.
Have heard that the petcock was installed way back when to make the non-starter T's crank easier with more air???
Makes for good conversation I guess.
Isn't there a book about Engine parts differences about that by Gail Rodda?
Yes but the book does not get into the minor differences between them between 1914/15 and 1927. The other holy grail would be the 1915 center door intake.
How can you tell the first cast iron type after aluminum? This was on my 14 engine (1913 cast date) when I got it, but I don't know if it's original to the engine.
Curiouser and curiouser...
The my understanding from information I have seen, the first cast iron intakes used the same molds as the aluminum ones. If you look at the aluminum intake they are rather larger where they mount to the block as are the tubes and neck. Guessing that the cast iron were shaped the same. If you look at the photo Chris posted in above link you get an idea of what the early cast iron intake might look like. While the photo is of a modern aluminum the outside shape is very similar to original aluminum intakes I have seen.
Corey, yours looks to be the newer style.
If you know what you are looking for it's one of those shapes that just kinda jumps off the page even under a coat of paint.
Rodda's Volume 1 shows a half dozen different ones, but there are more.
Our random thing done this past Sunday was for me and my wife to take the dog for a good long ride in "her" (the dog's) model A. She loved it. Miss Queeny in that big back seat.
A few pictures of my cast iron manifold made with the mold from the aluminum manifold. The priming petcock is, of course, an aftermarket accessory.
The factory number:
Bill thanks for the photos. Do you think it's any bigger on the inside then the later cast iron ones?
Mark, I've got one, too, but I have never found a part number, casting number, or even the casting 'dimples' on the side facing away from the motor. It does have larger passages as compared to a standard T intake. I'll post a picture if I ever get around to taking one.
I looked at Rodda's book here at the shop. Our copy, while an official copy, is one of the reprints of a reprint. It only shows 2 versions of the 14 up cast iron intake and they are shadow images as it is.
I'm no engineer, but I think "high volume intake manifolds" are overrated! At least when used with the most commonly used Model T carburetor,...the NH Holley. I think the diameter of the venturi in the NH Holley carburetor is the limiting factor in the intake system, no matter how "oversize" the passage(s) are in the intake manifold. In fact, I would think that the velocity of the incoming air/fuel mixture would decrease as the size of the intake manifold passage(s) increase. There are those who actually report a "decrease" in engine performance with "high volume intake manifolds", and I think this may be why. Interesting thread though,........harold
The Chaffin's high volume intake manifold I installed years ago along with the twin exhaust manifold had an immediate performance increase for my 26 using an NH carb. Jerry.
My understanding is that longer plenums generate more torque, but that much more performance is gained from reducing exhaust restrictions.
Unfortunately, the dual exhaust manifolds seem overpriced. Is there a good thread on porting exhaust manifolds?
I changed my Grandfather's 27 coupe from the high volume iron intake and a Holley three screw 'puddle' carb, to an regular iron intake and a Holley NH just to see the difference. The loss of performance was noticeable. I've heard people say that Holley three screw 'puddle' carbs don't make power. I differ with them.
I used a Metz intake (larger volume) with a variety of NHs and then changed back to the more typical ford intake (found one with good script) and noticed no seat of the pants difference. I wonder if the statements above regarding flow speed of the mixture may be right on. As long as the carb is the smallest part of the intake passage, no gain from slowing down the fuel air mix with a larger volume intake?
Here is the metz intake next to a typical ford
That Metz looks like a cast iron version of Ford early dog leg aluminum intake.
This is just a top of the head idea, no scientific study involved, but I would think that the larger intake manifold would give better high speed with wide open throttle, but with partially closed throttle, make no difference.
I had an 1913 style original aluminum intake with my Kingston L4 on the car but only for a short time. I was not overly impressed with the low end speeds I drive, under 40. I went back to the stock intake. The best combo I have had on the car was a Zenith intake with a Stromberg, think it was an L1, it was a little too harry for my taste! I am running a Schebler now, need a bit more out of it but not as much as the Zenith/Stromberg. That is partly why I was look at the different intakes I have.
For better exhaust breathing you could use a Model A exhaust and intake. There have been a number of guys that use them without the adapter plate. You could make a longer tube to fit between the carb and manifold to eliminate needing a fuel pump.
I went through my pile of manifolds (60) and found no early style; however, I have about five with Ford script. When was the Ford script added or discontinued? They are not very common.
I was told, by an old T guy, that the letters found on some intakes mean something. He was on the lookout for certain letters. Maybe a Secrets of Speed thing?
I have been using an aluminum manifold designed for an up draft model A carburetor. It is larger compared to other original manifolds that I have seen. Tried the model A Zenith, model B, square body-no name and Tillotson carburetors with this manifold and found the Tillotson performs the best on my car. Very happy with how the Tillotson performs and the MPG is normally over 20.
Verne, the intake manifold 'letters' were designations for different castings. A few years ago, someone ran a flow bench test on T manifolds and carburetors and the results were printed in an article published in The Model T Ford Times (MTFCI)
Thanks Terry. I will look it up.
Do you know what issue that was in? I have a small collection of The Model T Ford Times. The only related thing I could find was the Carb flow test in the March-April 2014 issue.
I had my 1914 iron manifold handy, but not a later 1915-26 manifold, but as you look at the pictures and see the weight and the diameter of the ports and carburetor opening, you can compare it to your later manifold. The ports and carburetor intake bores are constant. They do not taper down inside the intake manifold. Because of picture size, even though I resized them, they will be on three posts.
Carburetor opening is 1.250" and a standard T carburetor has a 1" throat. Also shown in pictures above, are the port opening size at the block mounting.
Mark and Verne, I may be mistaken. I thought the article tested intake manifolds and carburetors. I know that I've seen intakes tested somewhere because I remember the article talking about the different letters marking the manifolds.
Mark, I found it again. November-December 2009 issue The Vintage Ford MTFCI