Socket size for connecting rod cap bolts on A Engine

[mjr67]

Working on my old Model A block today and got the oil pan removed. Lots of sludge oil... It seems the connecting rod cap nuts is 21/32... Bought a 21/31 12 point socket and it doesn't seem to grab like it should and wants to round off the edges of the nut I tested it on... Looks like I'm gonna have to order a 21/32 6 point socket...Should have known better...

The 1 3/8 socket I bought to remove the crankshaft pully nut doesn't fit either... too tight to go on.. I think its rust build up on the nut...

Any advice is appreciated.
Thanks

 

[ed thibodeau]

I have seen rod nuts in 5/8 21/32 and 11/16, so check them all.

 

[CarlG]

The "rebuilt" engine that was in my PU when I bought it had a mix of sizes. As Mr. Thibodeau says: check them all.

 

[V4F]

if you mean the square nuts , use an 8 sided 9/16

 

[Wm J.]

The 17MM is a perfect fit. Been using one for years.

 

[jetmek]

yeah the original ones were 17mm

 

[C26Pinelake]

yeah the original ones were 17mm

I would very much doubt the original was metric ( 17mm )! Wayne

 

[George Miller]

Original nuts took a 21/32 socket.

 

[CarlG]

17mm = 0.6692913 inches
21/32 = 0.65625 inches

17 mm is oversize

 

[Y-Blockhead]

Ooooo, by .013". Make sure you use a 6 sided socket...