Hi all,

I recently ran across the following statement, regarding 413 blocks, from an anonymous user on a different forum. I am wondering if anyone can verify this information, specifically boring it out to a stock 440 bore:

"These engines were produced up until about 1973. I have always found them to have standard 440 LY rods (1851535), and 6-bolt cranks. The blocks in these engines were actually originally supposed to be 426's, (you can find the casting number 2658836 on the top rear of the block, near the oil pressure sending unit) and they were, in fact, "under-bored" .070 to 413 size (4.180). I have sonic-checked many of these blocks, and the cylinder walls are much thicker. So much, in fact, that you can bore these to a stock 440 bore (4.320) and still end up with the same cylinder wall thickness as a regular factory 440. There is considerable additional webbing along the outside of the block walls (where the freeze plugs go). The main saddles, supports, and main caps, however, are completely identical to a standard 440."

As always, I appreciate any information.

Roger