3989969 exhaust manifold "date"

[D S.]

I am baffled by some 427/454 exhaust manifolds on eBay that show J107 as a date code. I have seen several but those are not the date code casting patterns I have seen on original date coded exhaust manifolds. What is J107?

eBay Reference:

http://www.ebay.com/itm/1970-1974-Corvette-454-LH-Big-Block-Dated-Exhaust-Manifold-GM-3969869-NO-RESERVE-/181383386338?pt=Vintage_Car_Truck_Parts_Accessories&hash=item2a3b4ad4e2&vxp=mtr

Thanks,
Scott Sims
Texas Chapter

[Leif A.]

Re: 3989969 exhaust manifold "date"

May 10, 1967??

[D S.]

Re: 3989969 exhaust manifold "date"

If that is true there were sure a lot of them cast on that date.

[Terry M.]

Re: 3989969 exhaust manifold "date"

If that is true there were sure a lot of them cast on that date.

You think maybe all the reproductions were made on that date?

[D S.]

Re: 3989969 exhaust manifold "date"

You think maybe all the reproductions were made on that date?

Ya' think, Terry?

How have you been, my friend?

[Kenneth B.]

Re: 3989969 exhaust manifold "date"

J107 would be October 10 & year ending in 7. Maybe the Chinese patternmaker at the foundry forgot to change the date for a along time or the pattern for the repo. castings didn't have a interchangeable date tag.

[Joe L.]

Re: 3989969 exhaust manifold "date"

I am baffled by some 427/454 exhaust manifolds on eBay that show J107 as a date code. I have seen several but those are not the date code casting patterns I have seen on original date coded exhaust manifolds. What is J107?

eBay Reference:

http://www.ebay.com/itm/1970-1974-Corvette-454-LH-Big-Block-Dated-Exhaust-Manifold-GM-3969869-NO-RESERVE-/181383386338?pt=Vintage_Car_Truck_Parts_Accessories&hash=item2a3b4ad4e2&vxp=mtr

Thanks,
Scott Sims
Texas Chapter

Scott------

Very simple. This is a later SERVICE manifold. So, the date code represents October 10, 1977 or 1987 and most likely 1987. How do I know it's a SERVICE manifold? Note the "wagon wheel" symbol followed by a "D". This represents GM Central Foundry---Danville, IL. Original manifolds were usually cast at Tonawanda. However, the Tonawanda foundry shut down in 1984. After that time, big block blocks, heads and certain other parts were cast at Defiance, OH (which did not usually use a casting symbol). Other big block parts, including exhaust manifolds, were cast at Danville, IL. Danville-cast parts usually always carried the "D" casting symbol>

By the way, original exhaust manifolds cast at Tonawanda were gray cast iron. The manifolds cast at Danville were malleable iron, a much better material.

[Leif A.]

Re: 3989969 exhaust manifold "date"

Scott------Very simple. This is a later SERVICE manifold. So, the date code represents October 10, 1977 or 1987 and most likely 1987. How do I know it's a SERVICE manifold? Note the "wagon wheel" symbol followed by a "D". This represents GM Central Foundry---Danville, IL. Original manifolds were usually cast at Tonawanda. However, the Tonawanda foundry shut down in 1984. After that time, big block blocks, heads and certain other parts were cast at Defiance, OH (which did not usually use a casting symbol). Other big block parts, including exhaust manifolds, were cast at Danville, IL. Danville-cast parts usually always carried the "D" casting symbol>By the way, original exhaust manifolds cast at Tonawanda were gray cast iron. The manifolds cast at Danville were malleable iron, a much better material.

Joe,You are a veritable treasure trove of knowledge. I always enjoy reading your posts and responses. Just as an aside, I thought an "A" was for August, "B" for September, etc making a "J" for May. Did it change along the way? I know you'll have the correct response. Thanx

[John H.]

Re: 3989969 exhaust manifold "date"

Jo Just as an aside, I thought an "A" was for August, "B" for September, etc making a "J" for May. Did it change along the way? I know you'll have the correct response. Thanx

Leif -

I'm not Joe, but the dating format using "A" for August (or whatever the first month of model year production was for a given year) was only used on '63-'82 body trim tags for the body build date code. The date code format for GM castings used "A" for January, thru "L" for December, regardless of the model year.

[Leif A.]

Re: 3989969 exhaust manifold "date"

Leif -I'm not Joe, but the dating format using "A" for August (or whatever the first month of model year production was for a given year) was only used on '63-'82 body trim tags for the body build date code. The date code format for GM castings used "A" for January, thru "L" for December, regardless of the model year.

Thanks, John. This is one of the many reasons I follow this forum...learn something new every day.