@oi81b4uu812b4 .....So whats the inside scoop on the core numbers? The smoother resto 340 castings used the new sand and the production motors got the ****? Sound about right to me. Seems they would be sifting out the crap with every recycle. Wonder if the lower production numbers of the IH cast 318's had any better surface finish. That would be a great field trip, to a casting plant.
Amazing that there is some knowledge of the “IH cast 318’s”
That brought back memories.
Chrysler’s main block and head foundry was in Indianapolis. Was known as the Tibbs Avenue Foundry. Back in the early 70’s Chrysler outsourced some of its 318 engine block foundry work to the International Harvester Foundry that also was in Indianapolis. I have visited the Chrysler Foundry many times, but was an employee of the IH/Navistar foundry from 1971 to 1997. IH cast 318 blocks for Chrysler from 1971 to about 1973. The IH portion of the 318 production was always only only a portion of the total 318 annual cast, and only for about 3 years. That is why the IH 318 block is rare,compared to a Chrysler 318 block. As the IH and the Chrysler foundries were contemporaries of each other, both used tooling and processes from that era, I doubt that one was much better than the other quality wise. The IH / Navistar Indianapolis Foundry from time to time did a lot of block and head casting for other companies. Sadly both the Chrysler and the IH/Navistar foundries in Indy have been leveled. One thing killed both of them, NAFTA.
In the mid 90’s the Navistar Indy Foundry cast nearly 50% of all of Cummins 6B blocks and heads as well as 4B and 6C blocks.
Those Indy cast Cummins blocks and heads did have a higher hardness than the blocks and heads that Cummins was getting out of South America.
To the extent that the Cummins machining plants did not like the Indy cast blocks and heads, but the Cummins Engineering folks loved them.
And back on the original topic. The numbers after the part numbers on blocks and heads have absolutely nothing to do with the iron poured out of the ladle. The numbers are ‘pattern’ numbers. With the patten being the hard tooling required to make the mold shape.
Typically blocks are poured two at a time,
so the first set of pattern produced would be 1 and 2, the next set would be 3 and 4. Each set of patterns could produce maybe 50,000 to 75,000 castings before they would need a major refurbish. After maybe 100,000 to 150,000 uses or molds the pattern is worn to the extent that it is cheaper to replace than refurbish, so pattern sets 3 & 4 and 5 & 6 and so forth are made and used in production.
Concerning quality, all the patterns would be updated nearly constantly to incorporate changes that would reduce rejects and improve quality.
Major reductions in defects like core shift would happen with casting technology and capitol equipment improvements, that happen over decades, not with pattern replacements.
