MTFCA Forum

Any comments are appreciated about installing Model A B camshaft in a Model T. My biggest question is the offset in the end cylinders, just like if you install a Model A crank. The offset is about .090. Do you use a different lifter, A and T have the same size foot. There is not alot of room for bigger foot at the front. It is certainly better for the center of the lifter to be centered with the valve instead of offsetting the lifter bore.
Lobes when they are new have a slight offset crown, this causes the lifter to rotate, which puts this twisting motion into the valve. This keeps the valve from coming down in the same location every time. Am I overthinking this?
B cam has .310 lift, is that a problem sliding through the bores?
I can deal with the machining and welding.

I think Dan McEachern can chime in on this one, I hear he modifys A cams for the T block.

Tim.

I’ve done a couple of them. No problem with the lifters.
I’ve done BIG aggressive cam grinds. Had to file notches in the front and center cam bearing bores (2 in the front and 1 in the centre)
Removed the rear cam bearing.
I actually have one in process right now.

Definitely interested in learning more about this.

Sean
I will try to take some pictures and post them. Probably tomorrow.

Les Schubert wrote: ↑

Wed Dec 23, 2020 1:09 pm

Sean
I will try to take some pictures and post them. Probably tomorrow.

That would be great. Look forward to seeing them.

Finally got enough snow cleared to get to the shop (we had 15” here Monday Tuesday)

My question is why?? Far from a expert but i think there are several profiles of Model T cams so would it be worth the effort to use a Model A cam?? Bud.

Bud
The bigger camshaft allows for a MUCH more aggressive cam profile. The cam pictured is about.320 lift. The engine requires 4 separate intake runners to get a decent lower end torque but pulls strong to 5,000 rpm!!

Les, are you machining the main bearing surface of the cam to run on the block like a Model A? Also the thrust surface at the front of the block is only rearward like a Model A? Did you weld on a blank at the front of the cam for the timer and then machine, or ?

Seeing that you fella's are talking cam shafts, maybe someone can tell me what I've got here. I removed it from a T engine that was to be a speedster that was built a long time ago and never started, the lift is maxed out to bearing height and as well has a very long duration. cam is next to a stock one to compare.

Kerry, I dont know anything about your cam, but i wish it was mine.

Steve
You can buy a kit from some of the usual suppliers that is designed to “fix” excessive end float of the camshaft. It uses the front cover to control this. When I did this 45 years ago I brazed up some spots on the front cover and ground them to fit. That solution is still working on that engine and I will probably do that again.
With the oil pump drive on the back of the camshaft there may be little tendency for it to “bounce” forward (but I will do something anyway)

I bought a 3/4th race cam about 30 years ago from a guy in New Hampshire.

I have no idea what that means or is different, but the T would easily do 55 mph on the level and could gain speed on most hills.

The cam pictured installed in a A cranked T engine is capable of cruising easily at 75 mph and is capable of 100 mph. It pulls strongly to 5,000 rpm. Here is a picture of me sitting in it about 1985 as the body is progressing

Les, the bearing surfaces you machined to fit in the T block without a bushing correct? Or are you line boring the block to install bushings?

I didn’t rebore the cam bores. Machined the camshaft bearing surfaces to fit with about.001-.0015 clearance. Removed the rear cam bushing. No wear problems

How about the cam gear, do to the different CtoC of the locating pins. Did you redrill the gear or the cam?

Another way to get 4 intake runners is reverse engine rotation. A whole new can of worms, but can be done.

I hope these pictures help

Cam gear;
Several options. As pictured the front of a T cam has been added to the A cam. The first time I did this I refitted the T gear to the front of the A cam

bud delong wrote: ↑

Sat Dec 26, 2020 8:33 am

My question is why?? Far from a expert but i think there are several profiles of Model T cams so would it be worth the effort to use a Model A cam?? Bud.

I had the same question as Bud, but Les' answer that followed, answered Bud's question and mine. To someone with machine shop equipment and expertise to use it, an awful lot of modification is possible to a T engine; even enough modification to make the engine fast at the possible expense of reliability. Most T owners don't have the machine shop equipment or the knowledge to use it and have to resort to using parts made for a Model T. Two examples of this are the Stipe Machine Company .290 lift cam and the reground race cam from Antique Auto Ranch with .300 lift. If I wanted to modify anymore than that, I'd probably be looking at an OHV head, instead of a flathead.

Terry
The engine that I built in the ‘70’s has been totally reliable. No bearing or piston or valve issues! I am AMATEUR machinest with no formal training and the majority of the work I did myself. Yes I am a very skilled mechanical engineer with a long career manufacturing and inventing rotating machinery. But I am more than willing to share my experience with those that WANT to LEARN!!
All the best

Les, I appreciate your advice.Thanks for responding. Steve

Les Schubert wrote: ↑

Mon Dec 28, 2020 6:26 pm

Terry
The engine that I built in the ‘70’s has been totally reliable. No bearing or piston or valve issues! I am AMATEUR machinest with no formal training and the majority of the work I did myself. Yes I am a very skilled mechanical engineer with a long career manufacturing and inventing rotating machinery. But I am more than willing to share my experience with those that WANT to LEARN!!
All the best

Les, I am appreciative of your willingness to share your knowledge with all T enthusiasts, and I envy you, and if I had the machine shop tools, I would try some of your modifications, but I don't have the machine shop tools and have to stick to what I can bolt on "out of the box". I didn't mean to insinuate that your modifications weren't reliable, but there are many of us who don't have the equipment, knowledge, and skills that you do and many of us would fail trying to do, what you have succeeded to do.

Love your modifications Les. Thanks for sharing,jw

I was told that a "3/4 cam" was halfway between an "RV" cam and a "Full Race" cam...

I have NO idea exactly what that means in real world numbers for lift (.275" lift? .300 lift? .340 lift?) and the whole x degrees thing - How do you change a cam profile without totally screwing up a motor, what makes a cam more powerful vs more faster, etc?... It's one of those "secrets of speed" that was going to come up with my guru at the college but for this nasty thing called Covid which shut everything down. And I know it has to do with grinding a camshaft in ways to make it smaller yet make it bigger... What are the limits of "change" in what direction and how does what affect what?

Right now it all seems like black magic, and some of these secrets are still unknown to a neophyte like me (with a wrinkled magicians hat and too-long robes) but someday... someday...