Crank pulley thread size for 3 holes.

[justhorns]

I want to rotate my engine by hand, and wish to put bolts in two of the three crank pulley holes, and then use a screwdriver to rotate the engine. What is the bolt and thread size of those three bolts. My case is an 81 250-6 but I think all of the non bolted pulleys are the same. My crank pulley is dirty and can't get bolts to go in. Just wish to tap them to the correct size to clean out the holes. I know, dumb question, but, it helps...

 

[drumvirt]

I want to rotate my engine by hand, and wish to put bolts in two of the three crank pulley holes, and then use a screwdriver to rotate the engine. What is the bolt and thread size of those three bolts. My case is an 81 250-6 but I think all of the non bolted pulleys are the same. My crank pulley is dirty and can't get bolts to go in. Just wish to tap them to the correct size to clean out the holes. I know, dumb question, but, it helps...

Don't know the size, but could this work?: Spray WD-40 or such in the holes to loosen gunk. Wear googles and look out for spray back. When you think it's had time to soften the gunk, use compressed air and nozzle to blast crud out of holes and again look out for spray back.

 

[Radiohead]

Pull one bolt and verify this, but for some reason a 40 year old memory has that bolt at 5/16x18.
You don't have a sample bolt to check? Blast out a hole with brake cleaner and try a tap. This isn't rocket surgery.

 

[75gmck25]

Some of the vendors sell a bracket that bolts on the pulley using the three bolts, and then it has a 1/2” socket drive hole in the middle. Supposed to make it easy to turn the crank.

 

[justhorns]

I tapped the three holes to ⅜-16 I'm able to turn crank easily now with 3 temp bolts inserted. Excuse the bother, but between my back and my knees I just have trouble getting down there. I have work to be done before the surgery.