unusal bolt on fuel pump

[bmohan55]

Wife was out shopping last night so I thought Ii could steal some time wrenching on my truck. Went to replace the fuel pump when I came across this type of bolt securing it to the engine. I only have hex sockets, so what do I need to buy now??? Is this a typical bolt used or a P.O.S.T?

[Jeff Aronson]

I've never seen one like that on either of my II-A's, Bob. I have a couple of star sockets in my toolkit that might fit over that odd nut.

Anyone else ever seen one like Bob's photo?

Jeff

[SafeAirOne]

I've never seen one like that on either of my II-A's, Bob. I have a couple of star sockets in my toolkit that might fit over that odd nut.

Anyone else ever seen one like Bob's photo?

Jeff

I've seen tons of them--On F-18 fighter-jets. It's a spline nut. It should come out with a regular 12-point socket. Maybe even a 6-point, but it is designed for a spline wrench or socket. See:

http://www.mytoolstore.com/sk/sk89200.html

and http://www.fastenerdimensions.com/bolts_spline.html

[greenmeanie]

That looks like a high strength 12 point shoulder nut or what he said above. I know they are used on the big end studs on the Rover V8 at least but it's been so long since I opened up my 2 1/4 that I can't remember what's used on it. My bet is that someone dipped his hand into the jar of fasteners and chose the fancy nut by chance.

[scott]

i've just completed a rebuild of my 2.25 and there ain't no nuts like that anywhere on it. the fuel pump is secure with 2 studs 5/16-24 about 1 1/4" long and 2 5/16-24 nuts that go on with 1/2" socket/wrench. the studs have 1/2" of thread on one end and 3/4" on the other. the shorter end goes into the plate that's bolted to the block

[bmohan55]

that was it! Jeff's mention of "star" socket got me thinking so when I went home for lunch I rummaged around some of my old tool chests (I frequent a lot of flea markets) and found a 12-point 1/2 socket that fit it exactly. Before this I never really knew why those sockets exsisted except to strip Hex-heads. Best believe those won't be re-used.

thanks guys

[bmohan55]

BTW, the former owner of my truck was an aircraft mechanic for TWA...now it makes sense

[jp-]

I love those damn things! I'd put em all over if I had enough to go around.


I also like the 5 pointed (pentagonal) nuts. You ever see those?

[Terrys]

I love those damn things! I'd put em all over if I had enough to go around.


I also like the 5 pointed (pentagonal) nuts. You ever see those?

12 points are about the only thing GM ever came out with that made sense. I thought 5 point was only waterworks, or one of those funky gascocks.