1971 LT-1 Engine C11S106394 V1228CGZ

[John H.]

Re: 1971 LT-1 Engine C11S106394 V1228CGZ

John,

If GM experimented with this modification, and testing and warranty was involved in this experiment, how did GM track the evaluation blocks? If Terry M. is watching, I think he knows where I'm going with this, and I'm asking kinda tongue in cheek.

Ken -

Do you have the 2005 GM letters from Bill Nichols and Roger Wilson on this subject?

[Terry M.]

Re: 1971 LT-1 Engine C11S106394 V1228CGZ

Terry,

You mentioned member Mark Gorney in your post. Was he involved in the testing that John mentioned above, or is he someone who might have additional info on the "M" coded blocks?

Thanks.

Not that Mark has told me, and back when I explored the 0014 cases and the M code cases he didn't know anything more than what we have revealed to the membership in the stories in The Restorer and the TIM&JG --- however he used to work at what is now called Saginaw Metal Castings, and may still work there. I have not seen or talked to him since the Novi National last Summer. If any new information has come to light he would know.

Now you have the clues -- grab your mouse and click your way to the membership list and have at it.

[Terry M.]

Re: 1971 LT-1 Engine C11S106394 V1228CGZ

Ken -

Do you have the 2005 GM letters from Bill Nichols and Roger Wilson on this subject?

I am pretty sure Ken has them. To the best of my recollection I got the copies I have from Ken. But Ken shoudl speak for himself.

[Kenneth H.]

Re: 1971 LT-1 Engine C11S106394 V1228CGZ

John, yes I have them. I just reread them and, not being knowledgeable in metals or engineering, the Wilson document is mostly Greek to me. However, it appears, from what I can discern, that unless this experimental modification that we're discussing fits into the "Engineering changes" category, I'm probably barking up the wrong tree. According to the Wilson memo, it seems that the "M" code designation was used primarily to identify changes to the process of manufacturing the blocks, as opposed to the actual metals use in their manufacture. But who knows.

I just reread Gene Gamache's Restorer article "M WAS FOR MYSTERY", and it also confirms that the "M" code designation was used to identify a block "which was being tested for "process improvement"". However, Gene's article also alludes to not being able to find the records that would tell us about "the particular improvement to that block", which implies that maybe the "M" code designation might also have been used to identify blocks with composition improvements as well.

So, based on the above, and without additional historic information, even if the "M" code designation was used to identify "high nickel content blocks", we know that it was also used to identify all other "special" blocks as well, and I doubt that we could figure out which was which.

One last thought, as you already know, the "M" code designation blocks were not only found in Corvettes but were used in all Chevy models during this period. As a matter of fact, when I first purchased my LT1 and noticed the "M" date code, I googled M code and was taken first to a Chevelle site, and then a Camaro site both of which had "M" code threads. I guess this is a good thing since that means there are probably others out there that are seeking the same info on "M" code blocks.

Terry, thanks for your advice. I normally don't like to impose on others, but I'll contact Mark and see if maybe he can shed some light on the situation. I appreciate your guidance in this.