[LMSRACER]

[QUOTE=LPI;5335591][QUOTE=LMSRACER;5335556]
As for the Main Webbing Issues, that is more of a 400 Block Issue than a 455 Block Issue. In almost every case, the 455's Main Webbing is much thicker than the 400. Look for a 1970 to 1974 455 Block.

Can you explain how you come to this fact based on two major differences in amount of material in the block casting, a 455 has larger mains and a larger bore. In most cases the 455 blocks where drilled if not drilled and tapped for the outer 4 bolt main bolt holes, again a decrease in material and strength.

What main webbing on a 455 is specifically thicker than a 1967-to 1969 400 block.

I would like to learn what block castings you are specifically referring to and what specific area of the block are you referring to as being thicker. Would you please post a picture or a casting number that you are referring to.

The way that I come to this conclusion is that I have Ten Blocks here. I have '67, '69, '71 and '73 400 Blocks. Casting #'s #9786133, #9790071, #481988 and #481988 in that Order.
I have a Cast #9792968 428 Block.
I have a #9799140, #485428 (1971), #485428 (1972), #485428 (1972) 455 Blocks.
I also have a Cast #488986 350 Block (1974).

When a Say Thicker in the Main Webs I mean Below the Dowel Pin and Outer "Drilled" Bolt Hole Area. I Find that the #485428 455 Blocks aren't "Undercut" in this area at all. EVERY 400 Block that I have is undercut to some extent. This is where they Fail and this is what I'm concerned with.

The other place that Pontiac Blocks tend to Fail is Through the Oiling Hole to the Cam Bearing Tunnel. The 400 is "Theoretically" Stronger Here, of Course Due to the Difference in Main Bearing Journal Diameter and the Greater Amount of Cast Iron between these Two Points. I say Theoretically because often times this area of the Block is Cast "Thinner" in Areas between the Main Bearing Tunnel and Cam Bearing Tunnel.

I can Post Pictures if that won't Suffice.....

Have a good one,
Larry S.