Big Blocks built at the Tonawanda Factory

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I own a 1969 Pace car that has the L78 - 396/375HP motor. The date code on the engine pad is T0406JH. April 6th. This happens to be a Sunday! I have heard that the Tonawanda plant was so busy that it was operational nearly 24/7. Does anyone have confirmation that engines could have been built on a Sunday? I would appreciate whatever information you can give me...Thanks!

[buenymayor]

Can you post a picture of the pad stamp?

[boomer632]

Wouldn't mid a peek at that trim tag too..

[69Z28-RS]

Since the JH suffix code was used in multiple years, you also need the casting date of the block...

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I took a couple of pictures of the pad stampings. A little tough without removing the alternator.
Picture of trim tag for the Z11 also.
I can't get to the casting date on the block right now but when I bought the car in 1991 I checked the casting date and it was before the assembly date.
I had removed the valve covers to check the casting numbers of the heads and the date codes and they were good also. I remember the dates on the L & R head were not the same.
Kind of makes sense that left & right heads might not be cast at the same time....sort of a mix and match.
Thanks for your help....Gary

[bertfam]

Gary, to answer your original question, yes, Tonawanda (as well as Flint) occasionally worked Sundays but it wasn't the norm. Saturday was fairly common but not Sundays.

However, unfortunately your engine is a restamp so you might want to check the casting number and casting date to see if it's correct for the 1969 model year. I also recommend you clean off the paint because it appears there may be something else stamped under it. Use paint remover or some other chemical and NOT a screwdriver of scraper as this will destroy the original broach marks if they're still there.

Ed

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Thanks Ed for the reply. What are you seeing that made you determine the block was restamped?
Was it the date stamp or the vin code?

[x66 714]

Probably option "C", all of the above....Joe

[bertfam]

What are you seeing that made you determine the block was restamped?

Gary, we don't divulge this information on public forums. No reason to give the fakers out there any more ammunition than they already have! All I can suggest is that you compare your stamp with known good JH stamps and the differences till immediately jump out at you.

Ed

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Thanks again Ed. As soon as I can I'll strip the paint off the pad and post the pic.
The car was delivered to Prout Chevrolet in Elyria, Ohio on 4/21/1969. If you Google Prout Chevrolet it comes back that they were very much into selling HP Camaros. It kind of gave me hope that they would be the type of dealer that would order a L78 Pace Car. One could only hope!
Your comments are appreciated....thanks.
Gary

[boomer632]

Since the JH suffix code was used in multiple years, you also need the casting date of the block...

Oh yeah? I thought that JH was L78 code for 69 MY

[bertfam]

I thought that JH was L78 code for 69 MY

It was, for the 1969 Camaro and the 1969 Nova, but JH was also used on the 1967 Corvette 427/435.

Ed

[68 Ragtop]

Stamp bad. Tag good. Congratulations on having a real pace car. Sorry it's probably not the very rare L78 version, but still a great car.