MTFCA Forum

Can someone tell me what the dimension is from center of crank to center of cam on a Model A?

http://www.fordgarage.com/pages/camcrankposition.htm
If you are putting an A cam and/or crankshaft in a T block you will still need to use the 100MM center to center by using the T gears.

The A/B cam crank center distance is 4.156/4.157".

The 1929 factory drawing shown in the link I posted shows 4.154 to 4.156 was that changed?

Thanks for the info. I have a Gene French line boring set up I have used on several T engines but it does not seem to set right on an A block.

Gene makes two different frames. The one that just does T blocks and the other does both. You may have the one that only does T so would not fit the A block. Suggest contact him.

This is the frame for both A and Ts. You slide the frame over into the next hole in the cam spacer. I have talked to Gene about it.

First, if Dan sees this, I was not trying to ask a leading question I would like to know if those measurements were updated.

Was Gene able to help? You don't say. If not, maybe a little more information and maybe someone can also try and help.

I have been trying to learn some of the basics re pouring babbitt and have picked up bits of info here and there. So any suggestions I make were picked up from people ether have done the work or sources that would be found doing a google search (like the link posted above).

Brandon:
the cam to crankshaft center distance is 4.155" - 4.157" on a Model A Ford engine … the center distance on Model T Ford is 3.937 ( 100mm ) … my locator brackets are clearly marked A/B or T … a locator bracket is used at the front and the rear of the engine block … regarding "centering" between the 1/2" mainbearing bolts … this can be effected by the position of the pan rail as related to the camshaft bore … you can add shims under the linebore frame to move the mainbearing bore closer to the bolts opposite the camshaft … to move the bore toward the camshaft you would have to remove material from the pan rail ( not recommended ! )… with the locator brackets your cam to crankshaft center distance will remain the same ...hope this is stated clearly … if you have questions you may call or email … always an optimist ...Gene French 970-581-2808 email gfrench1953@hotmail.com

Dan McEachern wrote: ↑

Tue Feb 25, 2020 10:57 am

The A/B cam crank center distance is 4.156/4.157".

Dan's Model A, Center, to Center distance, is correct. As you can see, it is plus, or minus one thousandths.

The Model T is 3.936-70 to 3.937-80.

Never did I see those Spec's over one thousandths, and I know 4.155-00, has nothing to do with Ford Spec's.

I have never had any luck with boring bars with fixed center distance arms getting a perfect centered crankshaft in a block.

To do that, you have to have to have an independent way to adjust the boring bar side ways, and then up, and down, after that. If not, you have rear main oil leaks, on a model A's, and B's, and others. A model T, rear main, off by .010 thousandths will put the transmission tail shaft off more then that in, the ball cap area.

On Model, A's, and B's, the shaft will hit the Aluminum seal on one side, eating it for more clearance, and the other side will have a .010 thousandths gap for oil. The pilot shaft also will be out of alignment by .010 thousandths, not good.

I have had many different Brands of Align Bores, all had the same problem. It doesn't do much good to get a crankshaft ground on the center line, and then Align bore it off .010 thousandths.

The way I fixed the problem in the Tobin-Arp is I cut 4 plugs, for, front, and rear, main holes. Between each plug, and boring bare there is about a .000-50 thousandths clearance, and they hold the bar in the middle of the main bolt holes, until the set up is done.

The up and down part of the setting is to Mici the out side of the cam bar, and the boring bar. That is center distance, Plus half of cam bar, plus half the boring bar. You can also confirm lash with gears, and a Dial Indicator.

Herm.