[sprechs69firebird]

I was looking at the mains in my 455 and noticed there were a second set of threads outside the main cap dowel. What's the deal with this? Does this mean I can put 4 bolt caps in? Or do they belong to something I don't remember disassembling?

[P@blo]

The block is drilled for the 4 bolt caps but came with 2 bolt mains. The two bolt use different dowel pin sizes and will need to be changed before the 4 bolt caps can be used.

[Hillard]

I have personally put 4 bolts on a 2 bolt block and the dowels were the same. You will need to line bore the block and don't forget to machine the thrust faces on the number 4 cap.

[P@blo]

I stand corrected

[Hillard]

Pablo, If you've seen something different let me know. I'm just telling you about my block. I've never heard of an issue with the dowel pins but ???????????

[RAIV55]

Originally Posted by 1050goat

I have personally put 4 bolts on a 2 bolt block and the dowels were the same. You will need to line bore the block and don't forget to machine the thrust faces on the number 4 cap.

this is correct.

FWIW, to cure loose dowel in the cap issues I've started using 8mm hardened dowels. They are enough larger to remove the loose area in the cap without removing too much material in the web. Ground a .314 chucking reamer to cut cap and web holes on size up to the last 1/8" in depth. Use a Sunnen guide hone to open the cap holes for a tight slip fit.

Works well for me.