Model A cam ground to "B" profile

[Bruce of MN]

Would your C cam or a Burtz cam and a 6:1 head need more carb than a Tilly? I like the stock carb linkage.

[nkaminar]

If you like the original linkage, try two Tilly's with a double updraft manifold. One stock carburetor and manifold really restricts airflow at anything above 1,500 rpm.

[Jim Brierley]

Originally Posted by jeepguy1948

I think that perhaps Jim you meant raise the CR (Compression Ratio) rather than HP

The two fastest and easiest way to get power out of am A/B engine is to raise HP and install a bigger carb.

Should have been "to raise compression and install a bigger carb".

Thanks jeepguy, My mind isn't as sharp as it used to be.

[Jim Brierley]

Originally Posted by Bruce of MN

Would your C cam or a Burtz cam and a 6:1 head need more carb than a Tilly? I like the stock carb linkage.

The tilly would be the limiting factor in HP. Either of the above cams would perform better with a bigger carb. One Stromberg 97 will produce 100 HP with an appropriate cam and head. e-mail me at [email protected] and I'll send you a dyno report on this matter.

[jeepguy1948]

Mine (memory) isn’t so great either, what were we talking about?

[Bruce of MN]

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I didn't want to go off buying a new hotter cam and have my carb making the HP gains not worth the work and money.

[jeepguy1948]

Here is a cam question that is not exactly what started this thread but I think it is close enough: I recently bought a B motor that was rebuilt some years back that has a “High Lift” cam in it. Unfortunately all paperwork has been lost and the seller (elderly, grumpy) has no idea what it really is. Nobody needs to tell me what “High Lift” means but I know it doesn’t mean much. I know how I can measure lift but not duration. Is there a way to determine what this cam really is? I’m tempted to just yank it out and put in one of Jim’s. I don’t like not knowing what I have. The engine has not been fired yet and probably won’t be for while.

[ModelA29]

Originally Posted by jeepguy1948

s there a way to determine what this cam really is?

https://www.motortrend.com/how-to/md...ee-a-camshaft/

[johnneilson]

Hmmm
So I just had this conversation this week with a friend
He sent me some timing specs that he measured
Of the timing specs only the 050 numbers made any sense
Even after discussing the duration at 050 I asked him what vehicle it was going in
He said nothing right now but wanted to know
Ok so this information is only a small component in the overall motor and performance
Yes it is nice to know but without actually running the motor on a dyno or in a car it is insignificant
Something that really impacts the motor characteristics is the cam timing and lobe cl
One can be changed pretty easily the other not so much
If you need a name and grind number buy a cam from Jim

J

[Jim Brierley]

You can get an idea by putting a degree wheel on the crank and marking the degrees when the valve starts to lift, and when it hits the seat after going thru it's cycle. This is fairly accurate but not as much as when done in a cam doctor or in a lathe with a degreed chuck.

[Pete]

Originally Posted by Jim Brierley

You can get an idea by putting a degree wheel on the crank and marking the degrees when the valve starts to lift, and when it hits the seat after going thru it's cycle. This is fairly accurate but not as much as when done in a cam doctor or in a lathe with a degreed chuck.

Don't forget a cam grinder.

[jeepguy1948]

John, I have purchased 2 cylinder heads and 1 cam from Jim and am not adverse to buying another but I don’t have enough money to be stupid with it. Also, half the questions I ask on the forum are because I am curious and trying to learn.

[johnneilson]

Jeep

Let me ask you a question
Do you salt and pepper a steak at a restaurant before tasting?

Don’t get me wrong asking questions is great, the secret to racing is to ask questions
The secret to going fast is to ask the right questions

I have made a few cams and worked with a few grinders over the years
I can make some pretty good estimations of where to start with a cam but I use data and run the motors to make decisions about the package

I also use some pretty extensive software in comparison to determine where to start

So to ask, what is the measured lift of the existing cam?
And is it a large journal cam?

J

[Jim Brierley]

Originally Posted by Pete

Don't forget a cam grinder.

Pete, I don't know any good cam grinders, do you???

[Pete]

Originally Posted by Jim Brierley

Pete, I don't know any good cam grinders, do you???

Yup, I know a half dozen or so and they are some of my best friends.

[Jim Brierley]

- Me too!

[Dan McEachern]

ok you guys! knock it off!

[ModelA29]

MARC has the stock spec for the A & B cam on their site: https://model-a-ford.org/top-page-1/...pecifications/

[gdmn852]

Hello, doesn’t the B cam have different cam followers, lifters than Model A , thought the base of B cam followers, have a larger diameter?

[alexiskai]

Originally Posted by gdmn852

Hello, doesn’t the B cam have different cam followers, lifters than Model A , thought the base of B cam followers, have a larger diameter?

This got covered fairly exhaustively here:
https://www.fordbarn.com/forum/showthread.php?t=331692