Noticed something interesting on my LT5...

[1989ZR1#74]

Originally Posted by bdw18_123

Any thoughts on the dates in my above post?

Sorry missed, the previous post.

I am a little curious about the gap between the "priced date" and the block date. The price date is typically the date the car is completely assembled. There is a 76 day lag between the two. That to me would seem quite a bit longer then what I would expect. I would imagine that Mercury Marine was working at about their maximum output to keep up with the 1st year supply demands. It seems unusual that an LT5 would be out there for more than a week or so. MM was struggling to keep up with demand

From "Heart of The Beast":

"As the ZR-I was launched and demand for the car soared, MerCruiser struggled with both demand for the engine and its supplier problems. Production was falling behind demand for a number of reasons. Steve Campbell, who joined MerCruiser in the mid-Seventies, was directed by MerCruiser president David Jones to take over LT5 project management from Jim Cunningham in June 1990."

"Chevrolet could not build a car that was the class act of the world unless the LT5 was the class engine of the world. Certainly, meeting production demand was part of all this. By October 1990, MerCruiser had made up all the backlog and was producing 22 engines a day. Two months early"

So I would think a 76 day lag was almost impossible without some intervening story. The evidence is there. A double stamped block in two places 76 days after it was made. In an environment that could not keep up demand. So I revert to my original idea hypothesis. For whatever reason the block was sourced for a different ZR-1 was not used, and due to the lack of LT5 supply was repurposed for #2299.

Although I think the "Mary" failures did not start until December of 1990 so that more then likely has nothing to do with your 5/22/90 ZR-1.

FWIW here is the quote about Mary from "Heart of The Beast":

"They both heard the familiar whine of the Nippondenso starter motor of the LT5 as a ZR-I was being started up but then heard the LT5 immediate go to maximum rpm-something no ZR-I owner in his or her right mind would ever do. Behan turned to Barton and said, "I think I' ve found our problem." He walked over to the young woman starting the cars, introduced himself and asked her if she started all the cars that way. She said yes. Behan tried to maintain his composure. In all of Lotus' development and durability testing, they had never started a car in such a manner in such cold weather. Still, simply starting the engine in such a way could not explain why an LT5 had failed while still in Bowling Green. But Behan felt sure this abusive starting technique definitely had something to do with it."


I can't wait to find out why this happened, it will be an interesting footnote to the legacy of the ZR-1

[bdw18_123]

Originally Posted by 1989ZR1#74

I can't wait to find out why this happened, it will be an interesting footnote to the legacy of the ZR-1

Thanks for that info!

It's cool that my Z has an interesting history & I too want to know all the details about exactly how and why this happened. I just spent probably around 7 hours typing up all the service history, milage & dates info that I have. I would never have done that with any other car. I didn't even do that with the '93 Corvette I had. I guess the ZR-1 bug has definitely bitten me.

But unless other documentation can be found or someone remembers my car or another car that a similar thing happened to, we might not ever find out the reason. Hopefully though, we do figure it out.

[LGAFF]

Anyone ever think that maybe someone at the plant was just hungover and stamped the same # twice and had to fix it? Bound to happen in 6K stampings.

[1989ZR1#74]

Originally Posted by LGAFF

Anyone ever think that maybe someone at the plant was just hungover and stamped the same # twice and had to fix it? Bound to happen in 6K stampings.

Yeah I did, but that would have to be two hungover people in two plants. Hundreds of miles apart on an LT5 that just happened to be lying around for 76 days in an environment where they were behind the schedule on delivery so every LT5 build was close to immediately installed. In the NCRS world we call this NTP (Not Typical Production).

Anyone else have a #2000 range 90 ZR-1 that can findo out their block date/price date??

[tomtom72]

My Z is a 90 number 2233, my door sticker says May 1990......tell me what I'm looking for and where to find it and I'll see if I can get it done in the near future. Oh, forgot I do have a copy of my build sheet from the NCM.

We have a bit of snow that's causing some issues and it may be hard to find parking at my garage site. Besides, I will have to wait till the wee hours as I'm not allowed to do mechanical work in my rented space....


Tom

[1989ZR1#74]

Here is my summary of ideas:

1. Original block damaged sent back to MM for repair. MM sent replacement and restamped. FALSE, Jerry's MM source says he only remembers 1 LT5 coming back from a dealer and it just had carbon build up.

2. Car had original BG LT5 damaged as it was driven out of the plant by "Mary" Replacement was installed that had been planned for another ZR-1. False. "Mary" did not start killing LT5s until the Cold December of 1990. #2299 was build in sunny warm May of 1990.

3. Somehow a rebuilt LT5 was installed at the factory due to limited LT5 supplies. FALSE, LT5s were not rebuilt they were destroyed. To expensive to a repair a terminal LT5.

4. An LT5 that was planned/stamped for another LT5 failed to get installed. This LT5 was later restamped and installed in #2299. Similarly to how Jerry found an LT5 in Chevrolets crate motor stock with a vin stamped in it. They confirmed that the car that had that VIN also had a correct VIN stamped motor. OPEN. If it happened once it cannot be said it never happened.

5. Bock gets cast and set aside for 70 days. MM assembles the LT5, then stamped the wrong assembly seq number. MM employe grinds off wrong number to correct it then sent it to BG. BG employee stamped wrong number on pass side, realized it XXX'd it out the stampred correct number on driver's side. Installs LT5 and #2299 leaves BG to resurface later with everyone scratching heads... OPEN. Not to plausible in my mind but it could have happened.

More thoughts on the restamp. Since this LT5 has two apparent restamps, both with apparently correct fonts. This block was restamped at both locations. Here is a question for MM. What were the reasons MM would restamp a block? Did they only do this if there was a "hungover" guy who messed it up? Were there other reasons?

[1989ZR1#74]

Originally Posted by tomtom72

My Z is a 90 number 2233, my door sticker says May 1990......tell me what I'm looking for and where to find it and I'll see if I can get it done in the near future. Oh, forgot I do have a copy of my build sheet from the NCM.

We have a bit of snow that's causing some issues and it may be hard to find parking at my garage site. Besides, I will have to wait till the wee hours as I'm not allowed to do mechanical work in my rented space....


Tom

Thanks Tom, It is a bit of a PITA to see the date on the block. You can start by jaccking up the drivers side and looking at this number:



Your car is very close to #2299 ao it should be interesting to know.

Then the block date is on the driverside. In the area where it mounts to the bellhousing. It is very hard to see it when the LT5 is in the car. It can be done, but you probably wont be able to take a picture of it:



I have heard you can see this from the firewall side of the car looking down. Not sure though.

[LGAFF]

Here is a thread on VIN stamps

http://www.zr1.net/forum/showthread....ighlight=stamp

[bdw18_123]

Actually, Eric, the last picture you posted showing the cast-in date of my LT5 is on the passenger side. The re-stamped VIN is on the driver's side.

Here is another interesting piece of this puzzle. The piece that is between the block and the oilpan has a cast-in date of 3/8/90. This would seem to indicate that this LT5 was started one day and finished the next day. I don't know if that was something that would happen a lot or not.

Since the last 4 digits of the re-stamped MM number indicates that this LT5 was the very 1st build of the day the stamp was done, I would think that day would have to be the 8th of March, 1990. Here is a picture of my LT5 with arrows pointing to both cast-in dates:


The other strange piece of this puzzle is the fact that you can just make out what the number was that MM tried to grind out. It looks like it might be X0052299 (I added the underline here). I can tell for certain that the 1st two digits of the last 4 ground out numbers are both "2's". The last two could be "0's" I suppose, but the lower part of those numbers are more flattened out like the "9" stamp would be, so that is probably unlikely. If you look at the first picture in my first post, you can kind of see the ground out number.

If in fact it is true that the last 4 numbers originally said "2299", that would mean that this engine probably was always originally intended for #2299. Maybe MM had a new employee that accidentally stamped the last 4 of the VIN instead of the number that was supposed to be there. That would also mean that MM knew what engine was going in what car (the first year anyway).

The fact that there was a backlog in the middle of '90 makes that more likely since there would be more orders for ZR-1's than the number of built LT5's. In '93, this would have been the opposite. They were making way more engines than the amount of orders for ZR-1's that GM was sending, since they were making the rest of the engines ahead of time for the Z's all the way to '95.

[1989ZR1#74]

You are right , and I knew that.. it is the pass side.

I'm I seeing thigns or are the two dates:

03/07/1990 on the block

and

05/08/1990 on the other part?

so there is a 2 month gap right?

The 05/08 part fits much better with the 5/22 build date. I wonder what range the MM stamp would have been in March of 1990? Any one have an early March 1990 ZR-1 engine stamp they can share?