Posted by Clint Dixon [172.68.58.86] on Sunday, May 06, 2018 at 08:42:01 :
In Reply to: Re: Cylinder Head posted by Vaughn [172.69.22.239] on Sunday, May 06, 2018 at 00:10:40 :
My '48 list shows block #1120 427 and head #1120 795. This would be a non-bypass head.
The next list in line (1951) shows only a new block #1326 828 but two heads: old head #1120 795 and new head #1326 311. I assume this new block and head would both have the bypass.
The next list in line (1953) shows only the new block #1326 828. The old head #1120 795 is still shown along with the new head #1326 311 being shown.
No indication of when the changes took place other than the 1953 list shows the oldest head being used for WDX through B2PW models and the newest head used for B3PW and B4PW models.
I had not yet consulted the newer 1956 list. It is interesting that it shows the "new" head being replaced again at engine number T137-33131. This replacement was probably a higher compression head.
In any case, my engine being a 1951 is much older at #T137-21440. And, typical of a lot of parts shown, they call our a change right between B2PW and B3PW. A few places mention that some of those changes actually took place several serial numbers into the B3PW run. The more I research, the more I am convinced the cylinder head was one of those items that did not change at the introduction of the B3PW model, but took place several serial numbers into the run.
Thanks for bring my attention to the 1956 pats list.
I was about to end this post when I ran across another thing I had not thought to look for - the water pump.
The 1951 list shows that the water pump changed from the old one with external bypass to a new one without external bypass at engine number T137-21560, a mear 120 engines after mine. The list shows that the water pump body cover plate, thermostat, thermostat housing (elbow), and a host of other related parts all changed at the same engine number.
This tells me (according to the parts list anyway) that I have the correct waterpump, head, thermostat, and thermostat housing -all designed with external bypass. I know the engine bock is original to the truck because of the title. It appears that the rebuilt pump I put in the truck several years ago came assembled with a newer cover plate. I caught it at the time and installed the correct plate. Otherwise, I would have not gotten far before coolant would have started coming out of that partially uncovered internal bypass port in the block.
Thanks everyone,
Junior
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