I am pulling apart a 260 ci Ford small block v8 and I just found that the crank bearing cap bolts are a strange size hex. They seem to be somewhere in the range of 18.5mm or 23/32 of an inch. Has anyone come across these before? I need to buy the correct fit socket. Does anyone know the correct size?
Thanks for the reply Crazy Steve and good pickup with potential differences between US and Oz versions of the motor. The 3/4 inch socket is just too loose to consider, even if I go for a 6 point. With the torque on it there would be issues. The size is def strange and sits between the 16th sizes and half way between metric sizes too. I have seen a mix of metric and imperial fastners come out if it so I dont know which way to go for these. Anyone else come across this?
In the past, there existed X/32nd sizes, as my (very) old Craftsman socket set will attest. Possibly?? I just don't know. Only other guess - A British size, Whitworth, perhaps?? Good luck.
I've never seen a 23/32" socket. I've got a 19/32" and 21/32" but I can count on my fingers how many times I've used either one in the last 35 years (and they're both at least that old. By the way, the only thing they fit was exhaust nuts). Here's the deal; a 23/32" head calculates out to .7188". A six-point 3/4" socket is .7650 inside across the flats. A 19mm socket is .7550" inside, or .010" tighter (good choice on a worn 3/4" bolt). A 18mm calculates out to .7088", but a 18mm socket measures .7188", or exactly the size of a 23/32" bolt head. So you may be able to beat an 18mm socket onto the bolts; a 12 point socket may be the best choice for this. While these '32 nd' sizes were available way back when, I haven't seen new ones in forever. Before you try this, you should probably verify the actual head size to see what you have....
I think even the British had given up on Whitworth thread in automobiles back in the '50's and the first Windsor small block (the 221) came out in late '61 and was soon followed by the 260.
I tried a 3/8 Whitworth (can't believe I have it) too small by the smallest amount. Regular 11/16 too small, 3/4 too big. 18mm doesnt get on, 19mm seems the closest. I put a feeler gauge in the side of the 19mm open ender and the gap is less than .25mm. I am going to go for the 19mm and replace the bolts once they are out. What a mystery but thank you for the suggestions.
I see sockets sold that are marked 23/32-18mm. So they are out there. I have only a 19/32 socket. Which was for Ford rod bolts, I think, when I was a kid.
Yes, Ford rod bolt nuts. It was a WTF moment when I was taking a 427 apart but I had an ancient 19/32..
.25mm is .010", and that's the usual 'clearance' allowed on a socket or wrench so it will fit easily. You've got 19mm bolt heads....
Here are the bolts. The 19mm multi hex ring spanner got them out ok still it was way looser than I was happy with.
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