ZR-1 Block Numbers

[1989ZR1#74]

Originally Posted by LGAFF

I think the question is, were the 93 motors built solely in 93 and after or was production started before......when Dominic bought the car he was told it had a service motor, but owner was not sure what year. I think the plenum indicates a 92, but were wondering if there was a possibility this could be a 4 bolt short block.

ZAA is a 2 bolt 1992 engine suffix. the casting date appears to be 10/09/1991. That is long before the 1993 model year, and they built 1992 MY Corvettes until July, a couple of weeks after the block was assembled

I guess you may never know until you dig in and look at it. But I would say no if I had to guess.

[XfireZ51]

As I understood it, the assembly of LT-5 motors had pretty well ended by 91-92. That includes service motors. The date on the hood indicates the car was built in June of 92. That coincides well with the VIN# being 474.

[LGAFF]

So does the 1059# that is stamped into the block and the girdle 0f 90 ZR-1 #702 indicate production sequence?

[1989ZR1#74]

Originally Posted by LGAFF

So does the 1059# that is stamped into the block and the girdle 0f 90 ZR-1 #702 indicate production sequence?

I don't think so, do you have a picture of the stamps? I have found matching numbers stamped in the heads and cam covers of 1989 #058. They are in the 600s.

[LGAFF]

D/sFront of block




D/sFront of Girdle

[LGAFF]

22 motors were produced each day
1992 Birmel went out of business
Last LT-5 was produced on 11/24/93

Hard to say if a 6/17/92 LT-5 would be a 2 or 4......we might be able to find the block # and it would tell us

[bdw18_123]

Originally Posted by 1989ZR1#74

Priced date is the date I am comfortable with calling the build date. Now there can be a lag. What was the shipping date? Corvettes sit for 7 to 10 days in the "hold lot" before they go "accross the fence" to the ship lot. So back 7 days off the ship date.

This one is still a mystery to me. I think it was a double Gaff. 1 at MM and 1 at BG. Remember that for evry 1 ZR-1 3 L98s were built on the line. So the engine stamper may have picked up the wrong L98 Stamp and wacked the block. Then XXX'd it out and applied the correct stamp. The MM stamp is the one I don't quite get yet, but based on our previous post on this one I am leaning that way as well. Eric

The "SHIPPED" date is 5/24/90, only 2 days after the "PRICED" date. Couldn't have sat for 7 days, could it? "INVOICE" date is also 5/24/90.

You're probably right about the re-stamps just being a screw up. Just so happened that both plants messed up on the same car! But still seems strange for there to be such a big gap between the block casting date (03/07/90) and the build/priced date (5/22/90), especially since ZR-1's were in high demand at the time. Over 2 and a half months.

On the MM stamp, they didn't completely grind out the original number, you can still make out part of the original numbers. I'm pretty sure that the last 4 digits were "2299", which would match the last 4 of the VIN. Interesting mistake for them to make, would mean they knew that this LT5 was going to be for 2299.

[-=Jeff=-]

just drop the pan already..

[A26B]

Look at the front cover to tell if it is a 4 bolt main engine. Lwr corner, driver side rounded = 375 hp 2 bolt, square = 405 4bolt.

[-=Jeff=-]

Originally Posted by A26B

Look at the front cover to tell if it is a 4 bolt main engine. Lwr corner, driver side rounded = 375 hp 2 bolt, square = 405 4bolt.

Aw, Jerry now you are taking the fun out of it..

good to know though