Stage 2 block, 197????

750H.P.V6

Brutal 6 Racing
It's a bit of a head scratcher. It appears to have all the same traits of the 153 blocks. It seems to me there were some On Center blocks made that had a raised cam tunnel. I have never seen one personally, I believe Prasad had one at some point. Can you take a rough measurement between the main bearing bore to the cam bearing bore?

Neal
 

WarWagon

Caustic Cacophony
Interesting find, Where do pieces like this come from Thumper?
Side tangent:
I respect your info and comments 750H.P.V6! Neal I seen your name dropped in a magazine over 25 years ago involved with a silver T type. There was great info shared in that before I found this board.
 

rollie

Active Member
Can is a 2.114
 

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Thumper

Active Member
It's a bit of a head scratcher. It appears to have all the same traits of the 153 blocks. It seems to me there were some On Center blocks made that had a raised cam tunnel. I have never seen one personally, I believe Prasad had one at some point. Can you take a rough measurement between the main bearing bore to the cam bearing bore?

Neal
I measured a 109 @ 2.030
A 016 off center and this 197 @ 2.035

I also measured the cam bearing diameter in the block.
109 @ 1.930
016 and 197 @ 1.915
 
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Anthony P

sharing knowledge with those who care to listen
was wondering if that block is a massaged 4X block - have different casting #'s than what rollie posted above in #24.
4X151981 - starter mounting pad and part of bell housing on block removed for upswept headers. pics attached.
cyl bore => 3.90 (pictured); another one was 3.95
cam bore => 1.9175 or 1.9155 (can't read decades old paper notes)
believe cranks were 3.59 stroke
lifter bores bushed/pinned on run blocks

4Xblockred4 copy.jpg 4Xblockred3 copy.jpg 4Xblockred2 copy.jpg 4Xblockred1 copy.jpg 4Xblockred5 copy.jpg 4Xblockred6 copy.jpg
 
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750H.P.V6

Brutal 6 Racing
The 4X designation was used for pre-production castings. I have seen a few different versions. I had a block that had the same 4X casting # as the one you posted. The modifications to the bell housing area and starter pad removal were done after the fact for chassis clearance from what I understand. Here are a couple pics of the one I had.

IMG-20120404-00725.jpg
IMG-20120404-00730.jpg

Neal
 

Anthony P

sharing knowledge with those who care to listen
thanks Neal for taking a moment to post that. twenty some odd years ago, the guys who worked on the program that I could ask questions to were pretty tight lipped. years later, they'd say, "that was a long time ago." some have since passed so not so easy to glean knowledge from the folks who have(had) first hand knowledge. still doesn't get anywhere to finding an answer for Bill and this 0197 block.
 

750H.P.V6

Brutal 6 Racing
I'm not sure I have any more ideas on Bill's specific block other than it would have to be one of the last On Center blocks cast as the casting # is numerically higher than the 153 block.

I do remember having a discussion with Kenny D back in the day circa 1995 about Stage 2 blocks and their availability. He mentioned that GM had cast 50 blocks but he wasn't sure they'd take time to machine them because they didn't feel the demand was there. Maybe this one of the last group?

As a question is there a U followed by 4 digits stamped into the forward face of the block? These numbers are sequential and should give insight into when it was machined. There was a whole discussion on this at some point but I can't find the thread.

Neal
 

Chuck Leeper

Toxic old bastard
Staff member
He mentioned that GM had cast 50 blocks but he wasn't sure they'd take time to machine them because they didn't feel the demand was there
I had 6 unfinished BMS cranks that I took to Kings and had them finished.
May still be some floating around. Would have CODY MSPT etched on the ft cw.
 

Thumper

Active Member
I'm not sure I have any more ideas on Bill's specific block other than it would have to be one of the last On Center blocks cast as the casting # is numerically higher than the 153 block.

I do remember having a discussion with Kenny D back in the day circa 1995 about Stage 2 blocks and their availability. He mentioned that GM had cast 50 blocks but he wasn't sure they'd take time to machine them because they didn't feel the demand was there. Maybe this one of the last group?

As a question is there a U followed by 4 digits stamped into the forward face of the block? These numbers are sequential and should give insight into when it was machined. There was a whole discussion on this at some point but I can't find the thread.

Neal
Ok, getting a idea on these, thanks Neal for your info.
The first block, prototype maybe? As the last casting numbers have been ground off and 197 stamped in its place, this one has no uxxx number on the forward face.
The second block with the raised 197 molded in the block does have a U003 stamped in it
Both blocks appear identical other than
 

750H.P.V6

Brutal 6 Racing
Which of the blocks is the one that has 0198U1283 on the front the one with the cast in 25500197 or the stamped one?

Neal
 

Mike T

Well-Known Member
I believe the last run of the 153's had all 4 mains cross bolted. My guess is that your blocks are from somewhere in the middle of development.

Back when we were trying to figure out if the #s were sequential or not we ask for numbers from guys who had the latest 153's and no one responded.
 
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