Noticed something interesting on my LT5...

[LGAFF]

Work order for rebuild:

[bdw18_123]

Originally Posted by 1989ZR1#74

Ok let me summarize my questions that will help decipher this mystery:

For now I am focusing on the Mercury Marine oil pan stamping and casting info. Any of these questions will move the ball forward:

What is a typical casting date for a May 1990 ZR-1 LT5?

What is a typical date separation on the upper and lower castings on any 1990 LT5?

What is a typical oil pan MM stamp number for a May 1990 casting date LT5?

What is a typical oil pan MM stamp number for a March 1990 Casting date LT5?

What is a typical oil pan MM stamp number for a #2000 to #2400 1990 ZR-1?

Anyone with this information on any 1990 ZR-1 may help so don't be shy post.

Apparently, the "ball" fell into a deep hole and got stuck...

Anymore thoughts on this, or is it going to stay a mystery forever?

[1989ZR1#74]

Originally Posted by bdw18_123

Apparently, the "ball" fell into a deep hole and got stuck...

Anymore thoughts on this, or is it going to stay a mystery forever?

Have not had anyone offer up any examples yet so its still 2 down and 7 yards to go. Someone did ask the Engineers at the Gathering about restamps during a session. They said they did restamp, and they did not "throw" any LT5s away. They were fixed and reused. In fact the LT5 in the 24 hour record car was a rejected and repaired production motor. It was originally destined for a production car but was pulled back. So FWIW it may reset the idea that this block was repaired. So now that the weather is nicer perhaps you May 1990 ZR-1 owners can check out your numbers and offer up a little info (pictures would be even better) Eric

[BlackWidow#2]

Years ago I heard that the replacement engine in the record car was rejected at MM for having the delicate silver finish tarnished, not internal damage, cosmetic damage only.
George C.

[bdw18_123]

I'm gonna resurrect this year-old thread and add to the mystery even more. During the process of reassembling my LT5, I have come across even more stamped dates. It seems that pretty much every major component has a date stamped on it.

I don't know what the typical date range for all the parts on the engine is. Should they all be within a month? 3 months? More? On mine, the earliest dated part I found is 9/20/89 all the way to the date on the girdle which is 3/8/90. That is an almost 6-month span which seems excessive to me. And the car wasn't even assembled until 5/22/90 which is the "PRICED" date on the original invoice that I have.


I've posted a list & pictures below of all the stamped dates I've found and what part they are on. Some of the dates have a letter after them.

Crankshaft main
bearing cap girdle ------------ 3/8/90

Engine block ----------------- 3/7/90 B

Oil pan ---------------------- 1/8/90 C

Secondary actuators --------- 1/8/90

Plenum ---------------------- 1/5/90 A

Crankcase
breather cover --------------- 12/22/89

Oil pan
suction tube ----------------- 9/20/89 B

Both cylinder heads also have a cast-in number "89" which could indicate the year, but I'm not sure.


Pictures:

Engine block & girdle dates.




There is also some free-hand engraving in the "V" area of the block under the starter with a date (matches the stamped date). I colored in the engraving with a sharpe to make it more visible.




Oil pan date, it's on the front, passenger side edge of the lower surface of the oil pan.




Secondary actuators date, which is the same date as on the oil pan.




Plenum date, this is on the bottom just behind the DIS module.




Crankcase breather cover date.

[bdw18_123]

There is also some free-hand engraving on the top of the crankcase breather cover with a date of "12-21-89" (the year isn't very legible, but that is most likely what it says judging from the "12-21" part that is legible), one day earlier than the stamped date.




Oil pan suction tube date, it's on the surface just under the metal netting. This picture was hard to take because the camera kept wanting to focus on the netting, not on the surface below it.




Possible cast-in dates on the cylinder heads. Maybe that symbol thing with the numbers in the middle in front of the "89" is part of the date code?

Driver's side head, there is a "V6" stamped on this head.




Passenger side head.