C-3--Big block exhaust manifold

[D S.]

The casting is #3969869 on the front and on the backside is J225 and 869. I assume the 869 is a repeat of the last three numbers on the front but what is J225? Date code? The JG says there is not a year digit.

Thanks,
Scott

[Craig S.]

Re: C-3--Big block exhaust manifold

Scott - it may be a date code on a more recent cast assembly....such as J22 1975, 85, etc...Craig

[D S.]

Re: C-3--Big block exhaust manifold

The JG lists this as being a 1970-1972 left side exhaust manifold and 3880828 as the right and no mention of a 3880827. The JG doesn't list a 3880827 as being Corvette but the 1970 Corvette Registry does for a 454/390 with automatic (suffix code CGW). Is this another case of the JG not having enough information at publishing time and will be added/corrected in the next edition or is the information in the Registry in error?

Thanks,
Scott

[Craig S.]

Re: C-3--Big block exhaust manifold

Scott - the 827 part is the 66-69 year 427 casting. The 869 is the 70-74. I have the 827 on my 66. The above info is from Alan Colvins books......I have always seen casting dates on the backs of any I have looked at....but I have not paid attention much to the C3 parts.....so I can't comment on the accuracy of the TIM&JG....Craig

[Dick W.]

Re: C-3--Big block exhaust manifold

The JG & TIM call for the 827 on the 66-69 and the 869 for the 70-74 LH manifolds. These numbers and applications came from viewing original cars. I have not seen any other numbers used. (I have only judged over 20 years so what do I know? )

[Joe L.]

Re: C-3--Big block exhaust manifold

Dick-----

....and you won't be seeing any other numbers on original cars. The 3888027, left side, and 3888028, right side, castings were used on all 66-69 big block Corvettes. There were TWO sets of PART numbers, though-----for AIR-equipped manifolds and non-AIR-equipped manifolds. For 1970-74 the left side manifold was casting GM #3969869 and the right side remained 3888028. The 3969869 was also manufactured into TWO finished PART numbers for AIR and non-AIR applications.

The 3888027 manifold will fit just fine for the left side of 70-74 applications and the 3969869 can be used for the left side of 66-69 applications. Of course, the forward exhaust pipe has to be changed, too. And, of course, such an installation would not be "correct". But, it can be done.

Also, the 65 Corvette big block manifolds can be used for 66-74 Corvette applications, too, if the forward exhaust pipes are changed, too.

There are no other Chevrolet big block exhaust manifolds that will fit a Corvette chassis. So, if it's a Corvette and it has cast iron exhaust manifolds, then it has Corvette exhaust manifolds (although not necessarily correct for that year model Corvette).

The Corvette big block exhaust manifolds were mostly unique to Corvettes. The only exceptions were that 1965 passenger cars with L-78 used the same manifolds as 1965 Corvettes with L-78 and 1966 passeneger cars with L-72 used the same manifolds as 1966 Corvette with L-72.

The Corvette big block manifolds will fit many 65+ passenger car chassis, though, and you will often find them on "hopped-up" passenger cars with big blocks.

[Craig S.]

Re: C-3--Big block exhaust manifold

Joe - you always state 3888027 and 3888028 in your post....my Colvin book lists them as 3880827 and 3880828........I was thinking that was correct? Colvin also lists the 869 as a 2" vs 2.5" outlet but I think that is a typo? This is from the Corvette by the numbers.....didn't go check the Chevrolet by the numbers series of books.......Craig

[Joe L.]

Re: C-3--Big block exhaust manifold

Craig-----

Yes, I transposed the numbers. I do most of this from memory and sometimes I get a "mental block" that causes this sort of transposition. On these numbers, it will likely happen again in the future, too, so be forewarned.

All big block manifolds, Corvette and otherwise, were 2-1/2" outlet. So, any information to the contrary is in error.

[Joe L.]

Re: C-3--Big block exhaust manifold

Scott-----

Is there a large "D" cast anywhere on the manifold? These manifolds were cast at the Danville, IL GM foundry and may exhibit casting date differences from manifolds cast elsewhere. I don't know if Danville-cast manifolds were ever used on cars in PRODUCTION, but they may have been.

The Danville-cast manifolds are better. They are manufactured from nodular iron. Tonawanda-cast manifolds were manufactured from gray iron.

[D S.]

Re: C-3--BBC exhaust manifold, Thanks!

Thanks to all who have responded and I consider all of you quite in the know as many of you are either NCRS judges or have had quite a lot of experience. I deduce that I need to stick with the 3969869 left hand and not worry about date codes (I usually do but this would be an exception) because the JG says date codes are not judged.
I'm still vague on date codes on the manifolds as the JG says it follows the engine block casting date with no year. Then what is date code J225? A post '70 service replacement?

Scott

[D S.]

Re: C-3--Big block exhaust manifold, 'D'

Joe, I believe there is a large 'D' on it between the front and second exhaust port.

Scott

[Dick W.]

Re: C-3--Big block exhaust manifold

Joe, I do not believe that the nodular iron manifolds were installed on the production big blocks during the era that we are concerned. I agree that the Danville manifolds are better, but the castings are so much "cleaner" than the Tonawanda castings. But that is also a dead giveaway on the judging field.

[Joe L.]

Re: C-3--Big block exhaust manifold

Dick-----

Yes, I doubt that the Danville-cast manifolds were ever actually used in PRODUCTION, too. I expect that the casting of these manifolds was transferred to Danville after the Tonawanda foundry shut down permanently in 1984. However, it's possible that it was transferred prior to that time---sometime between 1974 and 1984.