CRG Discussion Forum

Camaro Research Group Discussion => General Discussion => Topic started by: maroman on January 30, 2018, 11:45:16 PM

Title: Ralley Green Z at MCACN
Post by: maroman on January 30, 2018, 11:45:16 PM
Does anyone know anything about the '69 Ralley Green Z that is both X-11 and has an engine with a M code? It was featured on Speedville site.
Title: Re: Ralley Green Z at MCACN
Post by: 69Z28-RS on January 31, 2018, 03:10:05 AM
I talked to the owner (Al Krebs at the time) two different years at the Camaro Nats..  I was a skeptic initially, but after much discussion with him, he made me a believer that the car is real...

Title: Re: Ralley Green Z at MCACN
Post by: Stingr69 on January 31, 2018, 01:09:46 PM
Whats an "M" code block?
Title: Re: Ralley Green Z at MCACN
Post by: 69Z28-RS on January 31, 2018, 02:05:58 PM
Hopefully someone that knows more about this will respond, as I don't trust my memory anymore on this sort of stuff, but IIRC from my discussions with Al, the 'M' was used to designate 'Test' or 'prototype' or 'developmental' casting; perhaps they'd made some slight change to the casting, but then decided that the block was usable as it was and proceeded with the engine build...   If I'm remembering this incorrectly, someone please update/correct this...

Title: Re: Ralley Green Z at MCACN
Post by: maroman on January 31, 2018, 02:16:21 PM
That is how it was explained in the article. It was a block cast to test a modification but not used in production, had no date code. I am not questioning this car, I have been around long enough to know you never say never. Stuff happens.
Title: Re: Ralley Green Z at MCACN
Post by: cook_dw on January 31, 2018, 03:42:36 PM
http://www.camaros.org/drivetrain.shtml#BlockCast (http://www.camaros.org/drivetrain.shtml#BlockCast)
Title: Re: Ralley Green Z at MCACN
Post by: westonz28 on January 31, 2018, 08:00:20 PM
Kurt will have to weight in on this one. I do remember reading about a original 1969 Z28 that had X11 on the trim tag. I bet Kurt has more information on it. This Camaro may be the "ONE".
Title: Re: Ralley Green Z at MCACN
Post by: maroman on January 31, 2018, 09:00:48 PM
It is claimed to be the only one with both X-11 and M code. As no Z-28s were to have X-11 it would be interesting to hear the story, if it was special order or mistake.
Title: Re: Ralley Green Z at MCACN
Post by: bcmiller on January 31, 2018, 09:08:29 PM
Thatís the car. November of 69 build. X11 was most likely a mistake on the tag - but the car was built as a Z - as intended.

Oh and on the M coded blocks, they used M because L was December - the last month of the year. I have had a few M coded blocks over the years and might still have one. Not sure.
Title: Re: Ralley Green Z at MCACN
Post by: maroman on January 31, 2018, 11:08:10 PM
Would they have used M code for all experimental blocks or just four bolt main?
Title: Re: Ralley Green Z at MCACN
Post by: bcmiller on February 01, 2018, 12:03:08 AM
Would they have used M code for all experimental blocks or just four bolt main?

"Research by the Saginaw Metal Casting Operations of GM Powertrain Division has found that these "M" codes are not date codes, but actually a foundry code used to indentify parts that were made to evaluate a casting process change."

There is no reason to think that it was only for four bolt main blocks.
Title: Re: Ralley Green Z at MCACN
Post by: maroman on February 01, 2018, 12:33:51 AM
I had read that. So, how are blocks marked as whether they are four bolt two bolt, etc.? I realize the blocks were probably not meant to be put into use but it does say they could be, as this one was. I had not heard of these M codes before.
Title: Re: Ralley Green Z at MCACN
Post by: bcmiller on February 01, 2018, 04:55:31 AM
Not sure there is a way to tell on a small block, its usually best to remove the oil pan and look.

There are some external clues on big blocks for 2 bolt mains versus 4 bolt mains.
Title: Re: Ralley Green Z at MCACN
Post by: ZLP955 on February 01, 2018, 10:27:15 AM
There are 'M'-coded heads too. I have a set of 3927186 'M' heads on my CE302. Have compared them to regular production heads and can't see anything obviously different, but so many subtle changes (including internally) could be possible during evaluation. I surmised that they were released into circulation (rather than being scrapped or returned for melting down) because their evaluation pattern was close enough to being finalised for production that it wasn't seen as risky - but purely a guess.
Title: Re: Ralley Green Z at MCACN
Post by: Kelley W King on February 01, 2018, 12:59:41 PM
There were more "M" blocks used than you would normally think. I remember years ago they were refered to as "Mexico" engines because they were thought to have been built in Mexico.
Title: Re: Ralley Green Z at MCACN
Post by: 68 Ragtop on February 03, 2018, 03:59:52 PM
You would think the owner would know there were more that 20,000 Z/28's made in 1969 and used the actual number in the poster board to gain more credibility, instead of a round about number.
I also think he is trying to say it is the only known real Z/28 with an X11 trim code, and in addition it happens to have a special casting date of "M". I am assuming the stamped codes are all legit. It looks like he is quoting Jerry M. on the poster, but can't read it. Anyone know what it says?
Title: Re: Ralley Green Z at MCACN
Post by: SMKZ28 on February 03, 2018, 08:28:58 PM
Here's the pictures I took of the car and the sign at 2017 MCACN.  The quote says, "This is the first time we have ever inspected a Z28 with an X code error," Jerry MacNeish.