The NCMTC fastener list shows the pan arm side bolt as 21/4" long, so that's what I got.
But it's obvious a castle nut won't go on here far enough to get a cotter pin through the hole. Either I'm missing something, or the bolt should be 21/2".
All the sources I have consulted say 2 1/4". Could your frame have spread a little and along with it the crankcase arms? If someone can provide a measurement between the inside frame channels you might be able to determine this. Jim Patrick
Well, we know the frame rail block is 1 1/2" thick. It should just touch the inside of the frame rail and pan arm. If the pan arm is 1/8" thick and the frame 1/4" (I think less), then that's 1 7/8". That leaves 3/8" for the nut and cotter pin out of a 2 1/4" bolt. That's not enough so the 2 1/4" bolt can't be correct.
The higher math confuses me so someone may want to verify it.
Ken is correct. The frame and the arm have not separated. Both are against the block. The bolt is simply too short.
The 2 1/4" bolt should be good. The frame is 5/32" think, the block should be 1 3/8" and the pan support is 5/32" think. Add it up and you get 1 11/16" and that leaves 9/16" for the nut.
Maybe your block is too thick, just shave it down to 1 3/8". Mine came as 1 3/8" from the supplier.
I was just looking at the block drawing going around. It shows 1 1/2" thick but it wouldn't be the first time a drawing was incorrect.
Yikes! That came out huge.
Yes, I see that the drawing does show 1 1/2" thick. Mine seemed to be thinner and some reported NOS blocks to be 1 7/16" thick.
However, even with a 1 1/2" thick block, the 2 1/4" bolt should work. That would make the total thickness of 1 13/16"
The wood block needs to be 1-1/2" thick to keep the crankcase arm from rubbing against the edge of the frame. The frame's edge can rub a notch in the arm, weakening it.
I'm glad you pointed that out. I'm keeping my blocks 11/2". If I can't get a pin in the bolt, I'll use a longer bolt.
It's the same bolt as the steering bracket bolt. Check it against one of those.
Steve - You might try a different style nut. I've always called the type shown in Jim's picture above a Castle Nut. The other style I call a Slotted Nut. The location of cotter pin is much closer to the base on a slotted nut.