The Stovebolt Site Forums The Shop Area Engine Shop 52 AD front motor mount bolts

Why the front motor mount bolts are like carriage bolts instead of hex bolt. Do you guys put hex bolt. I am in the process of putting the motor and I didnot get bolts with the new motor mounts. Do you guys know what size and which bolts I should buy.

Thanks as always

Ganesh

The mounting plate bolts are carriage bolts because the plate is stamped with a square hole to accept the carriage bolt because it prevents the bolt from spinning while tightening.With the fan and radiator in place space is limited for an open end or box wrench to fit the hex bolt head. If the radiator is removed, you'll have plenty of room for hex head wrenches. The original carriage bolt size is 3/8"- 24 x 1 3/4" and drilled for a cotter pin. Replacement carriage bolts don't have to be exactly that unless you're going for a pure restoration. Just use a 3/8" carriage bolt of the same size with a course thread and a nylock nut.

Thanks Drew, I went and bought 3/8" carriage bolt but the new motor mount plate doesnot have stamped square hole. It is chore always when removing those bolts for me, they keep spinning

Ganesh

I'm pretty sure the original carraige bolts are 7/16"-20 NF threads. You can make square holes by drilling the corners with a small drill, then drilling the center and finishing with a file as seen here:

http://s176.photobucket.com/albums/w186/curt160/mods/?action=view&current=frontplateholes.jpg

See the tech tips for a template.

Just ran into this myself, try getting the carriage bolts from a John Deere dealer, they had the bolts, some thick washers as well. Proper grade too. I know it sounds off, but they had the goods. Some old school guys have the stuff, but they want way to much $$ for automotive grade bolts in my opinion.

Hank

Curt,It's possible they are 7/16. I admit I was using a Master Parts Catalog that only went to 1951. By the way, I liked how you remade your shift box for manifold clearance.Very nice.