I need to know what the bolt size and thread pattern are for the bolt that goes in the middle of the crankshaft gear. I am missing that bolt and Chevy can't seem to tell me what it is.

This is for a 1991 Chevy 4.3L 262 Motor with a Z Engine Code.

They gave me a 7/16" bolt and that seems too fat, but when I try a 3/8" that just slides in and out.

Thanks, James

i do beleive it is a 7/16, its just a fine thread bolt.... if your having prolblems with it goin itn its possible u have someohje messed up the threads in the crank

7/16-20x2 1/4,washer is#14060682 group0.662.Hope that helps.Jon

7/16-20x2 1/4,washer is#14060682 group0.662.Hope that helps.Jon

I could swear when I put a 7/16-20x2 1/4 bolt into that, it looks too fat. I wonder if I should try and find a 7/16-20 tap and try that in it first. Maybe it just needs to be cleaned up a little.

I got the bolt size out of a Chevy parts catalog.I could be wrong.the catalog was dated september 1990.It`s for the 1991 year.I don`t know if this is when they changed over to metric fasteners.I don`t want to mess you up.If the tap dosent start easy I would stop.I called the local dealership and they only had a part number.Might be metric.Sorry Jon

It is 7/16-20x2 1/4, like I thought, and like you guys mentioned. Thanks...

I bought a 7/16-20 tap today and used that to clean it out well and then sure enough the bolt when in.

Thanks, James