I have searched this site and others regarding information on both the Oldsmobile NASCAR engine block and the HP engine block. I do not recall finding a single article with respect to the NASCAR block, and the threads/discussion of this block are very rare. There are a few very informative articles regarding the HP block and several threads/discussions. I am interested to find out which version of block came first, what the years used were, and why both blocks were made versus just one version - rule changes/cost/manufacturing reasons/etc.?

Regarding the NASCAR block is it known why both a siamese and non siamese version were produced? I'm not asking about advantages/disadvantages in comparing the two styles, but was there a rules change or reason for both styles to be produced?

Any useful information is appreciated.

 

Looked around also. With little info. Posted your question on facebook. And messaged Warren Johnson on a comment from someone on there.

 

I would ask question on Facebook:
RealOldsPower
Oldsmobile Max Performance

 

Too late, done that.

 

Oldsmobile In Action Volumes 1 & 2 are pretty good sources for the history.

 

You can read here, https://classicoldsmobile.com/forums...6/#post1386886

I think 72Supreme4Speed is looking for more.

 

The reference and link to Oldsmobile in Action were extremely helpful.

I looked over those pages of Oldsmobile in Action when they were originally posted last fall with the HP block and assorted parts for sale in the link but did not take in all the details. I have heard the engine block in question referred to as both HP and/or NASCAR, from the articles I have seen they seem to be clear that there was one block officially called an HP block, with many versions inside of one part number for the non-siamesed version and one part number for the siamesed version.They talk about prototypes and reference 1985 or later as an approximate time when the first HP block would be available. The articles have mentioned a progression in design with the HP block, even though it seems they all came with the thicker full main webs and thicker pan rails on the bottom at a minimum. It would seem the main bearing bores could be up to 3" on early versions but then are supposed to be a standard 2.5" on later production, there may be a blocked off, machined away, or properly cast injector pump locating area (gas block design) based on time of production, the casting identification may be the diesel ID with GM5.7L added in the middle or the actual HP part number based on time of production. It would seem the later versions of the HP block or those containing the HP part number cast into them are not as common, almost all that I have seen are the earlier HP with injector pump locating area machined away and the modified diesel casting ID. It would seem that the HP part numbers contain many variations of engine blocks, but at a minimum all have the heaver bottom end webbing and pan rails.

 

There maybe many more of these blocks out there. I was told second hand. At the AJ Foyt auctioned off his Nascar Oldsmobile parts. Guys where loading covered car trailers full of part. Including many of these blocks.

As the gentleman who sold me his AJ Foyt block, Batten heads with intake. He worried than as time goes on. People not knowing what they have. Because the original buyer has past. Will sell the everything for scrap!

As with the D and DX ones I found in a homemade shed in Utah. He had many Ford blocks and others saved with many engine parts. And one step away from being sold for scrap. Who know what else is out there.