Flywheel pressure plate bolt size

[Model A Bill]

I have what I believe to be a 49 to 53 flywheel.Truck or car I'm not sure.It has 3 sets of 2 holes ( not the evenly spaced holes around the flywheel) I'm attempting to mount my 10 1/2 pressure plate to the flywheel the bolt pattern on the pp is correct to the flywheel,but the thread size in the flywheel is 1/2 coarse thread? I looked through all the post that I could find and only saw where most flywheels were either 5/16 or 3/8 thread.Is this a stock bolt size or has the flywheel possibly been modified for some reason? Thanks in advance, Bill

 

[Fordors]

You could use these inserts, all on the page are 1/2"-13 external thread, available in 5/16"-18 and 3/8"-16.
http://www.grainger.com/Grainger/ke...g/N-8nyZ1z0jv1l?Ndr=basedimid10071&sst=subset

I would verify that the bolt circle for the pp is concentric with the flywheel, no telling what might have been done previously.

To see the intended page you will need to look at the column on the left, it reads "Refine by", scroll down to External Thread Size, and click on 1/2"-13.

 

[Walt Dupont--Me.]

I've never seen a wheel with 1/2in. thread. Are you sure you don't mean 5/16 course thread with a bolt head 1/2in. socket size? Walt

 

[rotorwrench]

The only guess I could venture is maybe an industrial application of some sort.

 

[Model A Bill]

Walt Nope its excatly as I described.1/2 thread put a 3/4 wrench on the bolt and tighted it up.I will post pics of it later Bill

 

[rotorwrench]

Quite a few flatheads ended up doing duty as power generators, welders, saw mills, and compressors. These applications didn't use a clutch but may have needed the weight of the flywheel to keep rpm changes more controllable. Plus they needed a starter ring. You could have it redrilled as long as the other holes don't get in the way.

 

[Model A Bill]

Here are some pictures of the mystery flathead flywheel.I was in the process of getting my stuff together last night to take to the machine shop today after work when I noticed the thread size was larger.The guy doing my work is going to redrill my flywheel to the correct size thread. I said I would post Pics so here they are Bill