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I came across a big block exhaust manifold today in a friend's attic and cannot identify the casting number in my books. Casting # 3969869 (I'm not positive about last digit, hard to read) also has a casting of GM2T. Can anyone tell me what this is for, I assume it's for a 427 Corvette as I found it with a 3880828 RH GM2 which is for a 427 425 hp I believe. Thanks in advance for the help, Kurt Bunting NCRS 26406
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Re: Big Block exhaust manifold
Kurt----
The big block exhaust manifold casting number that you're looking at, GM#3969869, is the 1970 thru 1974 Corvette left side manifold. This manifold replaced the GM#3880827 manifold used from 1966 thru 1969. All 1966 thru 1974 Corvettes used the 3880828 right side manifold. With respect to all of these manifolds, if they were originally used on a application which had A.I.R., they were drilled and tapped for the 1/4-18 fittings. Otherwise, they were not.
The GM#3969869 manifold differs from the 3880827 in two ways. First, its general shape is somewhat different. Second, the configuration and angular orientation of the outlet is different. This manifold can be used on 66-69 Corvettes, but the 70-74 left side forward exhaust pipe must also be used.
Lastly, the "GM2T" and "GM2" marks that you see are mold numbers. Coincidentally, both of these manifolds used a "number 2" mold, although the molds are obviously different for the left and right side manifolds. The "T" on the one mold number indicates that the part was cast at the Tonawanda, NY foundry which is adjacent to the engine plant. Since not all Tonawanda-cast parts carry the "T" mark, the other side may or may not have been cast at Tonawanda. Incidentally, the Tonawanda foundry(but not the engine plant) shut down in 1984, so if the part is dated after that time, it was cast elsewhere.In Appreciation of John Hinckley -
Re: Big Block exhaust manifold
Kurt----
The big block exhaust manifold casting number that you're looking at, GM#3969869, is the 1970 thru 1974 Corvette left side manifold. This manifold replaced the GM#3880827 manifold used from 1966 thru 1969. All 1966 thru 1974 Corvettes used the 3880828 right side manifold. With respect to all of these manifolds, if they were originally used on a application which had A.I.R., they were drilled and tapped for the 1/4-18 fittings. Otherwise, they were not.
The GM#3969869 manifold differs from the 3880827 in two ways. First, its general shape is somewhat different. Second, the configuration and angular orientation of the outlet is different. This manifold can be used on 66-69 Corvettes, but the 70-74 left side forward exhaust pipe must also be used.
Lastly, the "GM2T" and "GM2" marks that you see are mold numbers. Coincidentally, both of these manifolds used a "number 2" mold, although the molds are obviously different for the left and right side manifolds. The "T" on the one mold number indicates that the part was cast at the Tonawanda, NY foundry which is adjacent to the engine plant. Since not all Tonawanda-cast parts carry the "T" mark, the other side may or may not have been cast at Tonawanda. Incidentally, the Tonawanda foundry(but not the engine plant) shut down in 1984, so if the part is dated after that time, it was cast elsewhere.In Appreciation of John HinckleyComment
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Re: Big Block exhaust manifold
Does this paticular exhaust manifold have the AIR holes drilled and tapped. If not I am looking for one without holes for my 1970 LS-5. I have a 66-69 and a 70-74 manifold, both with holes tapped and plugged, that I would like to swap for the one you have mentioned without A.I.R. holes.TonyComment
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Re: Big Block exhaust manifold
Does this paticular exhaust manifold have the AIR holes drilled and tapped. If not I am looking for one without holes for my 1970 LS-5. I have a 66-69 and a 70-74 manifold, both with holes tapped and plugged, that I would like to swap for the one you have mentioned without A.I.R. holes.TonyComment
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Re: Big Block exhaust manifold
Tony, It does have the AIR holes. Sorry. KurtComment
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Re: Big Block exhaust manifold
Tony, It does have the AIR holes. Sorry. KurtComment
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Re: Big Block exhaust manifold
Joe, Thank you for your knowledgeable response. Both manifolds I found have the AIR holes. I have convinced my friend to sell them as he has no use for them. Any comments as to what their value is? I have no knowledge as to value since my 68 is a small block and God knows I overpaid for everything I've purchased thus far. Thanks again, KurtComment
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Re: Big Block exhaust manifold
Joe, Thank you for your knowledgeable response. Both manifolds I found have the AIR holes. I have convinced my friend to sell them as he has no use for them. Any comments as to what their value is? I have no knowledge as to value since my 68 is a small block and God knows I overpaid for everything I've purchased thus far. Thanks again, KurtComment
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Re: Big Block exhaust manifold
Kurt----
As I mentioned previously, all of the Corvette big block manifolds(except the unique manifolds used in 1965) were produced in both A.I.R. and non-A.I.R. configuration. For the first year of production of the #3969869 manifold, 1970, none were equipped with fittings since all 1970 LS-5s were non-A.I.R. After that, A.I.R. useage varied.
Good, used big block Corvette manifolds are worth about $150-175 each. Of course, there are many folks that think that big block anything is worth a king's ransom. But, you can buy these manifolds at swap meets for the price range I mentioned. By good condition I mean no heavy rust pitting, cracks, repaired cracks, or broken studs. Manifolds suffering from those conditions are worth considerably less. Or, if you're of my persuassion, nothing at all.In Appreciation of John HinckleyComment
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Re: Big Block exhaust manifold
Kurt----
As I mentioned previously, all of the Corvette big block manifolds(except the unique manifolds used in 1965) were produced in both A.I.R. and non-A.I.R. configuration. For the first year of production of the #3969869 manifold, 1970, none were equipped with fittings since all 1970 LS-5s were non-A.I.R. After that, A.I.R. useage varied.
Good, used big block Corvette manifolds are worth about $150-175 each. Of course, there are many folks that think that big block anything is worth a king's ransom. But, you can buy these manifolds at swap meets for the price range I mentioned. By good condition I mean no heavy rust pitting, cracks, repaired cracks, or broken studs. Manifolds suffering from those conditions are worth considerably less. Or, if you're of my persuassion, nothing at all.In Appreciation of John HinckleyComment
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Re: Big Block exhaust manifold
Joe, Thanks again for your input. I'm new to this forum and am impressed with the wealth of information that people like yourself are willing to share with those of us who don't know as much about our toys. KurtComment
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Re: Big Block exhaust manifold
Joe, Thanks again for your input. I'm new to this forum and am impressed with the wealth of information that people like yourself are willing to share with those of us who don't know as much about our toys. KurtComment
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