21 stud bolt pattern - anyone have it?

[Yoyodyne]

I'm going to make a an aluminum honing plate for my 21 stud block. Does anyone have a drawing or locations for the stud holes? If you can help me out you'll save me a tremendous amount of time reverse engineering used parts.

[34PKUP]

Originally Posted by Yoyodyne

I'm going to make a an aluminum honing plate for my 21 stud block. Does anyone have a drawing or locations for the stud holes? If you can help me out you'll save me a tremendous amount of time reverse engineering used parts.

And you don't have a head or head gasket to transfer from? (Doesn't have to be super accurate )

[Yoyodyne]

Because I'm going to use the plates for several things, I'm going to CNC profile the outline of the combustion chamber gasket edges into the plates and I want the bolt holes in the right locations. In this case for what I'm doing yes it does need to be accurate. An old ford drawing or similar to start with would be very helpful.

[JM 35 Sedan]

Originally Posted by Yoyodyne

Because I'm going to use the plates for several things, I'm going to CNC profile the outline of the combustion chamber gasket edges into the plates and I want the bolt holes in the right locations. In this case for what I'm doing yes it does need to be accurate. An old ford drawing or similar to start with would be very helpful.

Maybe if you contacted someone making reproduction 21 stud heads they would send you the type of drawing(s) you need. Kearney Pattern Works in California comes to mind as a company that might be willing to help. Also, maybe the Ford Archives/Benson Research Center in Dearborn, Mi might be of some help.

[51 MERC-CT]

Originally Posted by Yoyodyne

Because I'm going to use the plates for several things, I'm going to CNC profile the outline of the combustion chamber gasket edges into the plates and I want the bolt holes in the right locations. In this case for what I'm doing yes it does need to be accurate. An old ford drawing or similar to start with would be very helpful.

So are you saying that the relationship of the chamber edges on the gasket to the stud holes on the gasket is not accurate?

[Mart]

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FWIW quite a few stud holes are common between the 21 stud and 24 stud patterns. I'm thinking you could make one plate that would fit both.

Can't help with dimensions, I'd transfer them from a genuine ford head.

Mart.

[GOSFAST]

Originally Posted by Yoyodyne

I'm going to make a an aluminum honing plate for my 21 stud block. Does anyone have a drawing or locations for the stud holes? If you can help me out you'll save me a tremendous amount of time reverse engineering used parts.

We've made a number of block-plates, including the Flathead we use here, using the gaskets as a template, has worked really well. The one in the photo below was done on a "Hass" some years ago.

If you have access to a "CNC" you should be able to probe the holes either in a head or a block. Not sure what type CNC mill you are using? Probing all the holes will give you accurate numbers/dimensions.

Thanks, Gary in N.Y.

P.S. We use our block-plate also as a fixture to "pin" the heads and gaskets to all the Flathead units we build. It makes for longer gasket life, keeps everything lined up, same scenario as the SB Chev's!

[Yoyodyne]

Nice work, that's very much what I have in mind. My VMC doesn't have a probe, I'd have to indicate the holes and contours in a sheetmetal gasket which sure seems like a problematic challenge to say the least, plus I'd have to trust the gasket I chose.

Would you be interested in sharing your data? I assume you have only the 24 stud pattern? If so, It would still help as a good starting point.

Originally Posted by GOSFAST

We've made a number of block-plates, including the Flathead we use here, using the gaskets as a template, has worked really well. The one in the photo below was done on a "Hass" some years ago.

If you have access to a "CNC" you should be able to probe the holes either in a head or a block. Not sure what type CNC mill you are using? Probing all the holes will give you accurate numbers/dimensions.

Thanks, Gary in N.Y.

P.S. We use our block-plate also as a fixture to "pin" the heads and gaskets to all the Flathead units we build. It makes for longer gasket life, keeps everything lined up, same scenario as the SB Chev's!