67 exhaust manifold

[Joseph M.]

I'm looking to purchase an exhaust manifold for my 67 327-300. What would be the correct casting number? Thanks.

[Gene M.]

Re: 67 exhaust manifold

P/n's are in the judging manual, they are different on both sides.

[Michael J.]

Re: 67 exhaust manifold

Yes, and they are different if you have A.I.R. The numbers for 300HP are, non-A.I.R.: Left side: 3846559 & 384559A, Right side, 3747042. With A.I.R: Left side 3872765, Right side 3872778. Good luck.

[Jeffrey M.]

Re: 67 exhaust manifold

Hi Michael,
I have a 1966 327 california car (A.I.R.) The block was replaced along the way with a 3970010 cast block. I believe both blocks were 325, 350HP. The current block has the 3872778 RH exhaust manifold, but the LH has an exhaust manifold cast 3872786 also with A.I.R. holes. I am told that the LH should be 3872765. Does anyone know if the 3872786 LH manifold could be correct for the 1966 327 350HP or when it was actually used. I have search the internet but can only find a little about this manifold. Thank you for the help.

[John H.]

Re: 67 exhaust manifold

Hi Michael,
I have a 1966 327 california car (A.I.R.) The block was replaced along the way with a 3970010 cast block. I believe both blocks were 325, 350HP. The current block has the 3872778 RH exhaust manifold, but the LH has an exhaust manifold cast 3872786 also with A.I.R. holes. I am told that the LH should be 3872765. Does anyone know if the 3872786 LH manifold could be correct for the 1966 327 350HP or when it was actually used. I have search the internet but can only find a little about this manifold. Thank you for the help.

Jeffrey -

The 3872765 (LH) and 3872778 (RH) were used on both 1966 and 1967 327's with A.I.R.; have no idea what the 3872786 manifold was used for.

[Gerard F.]

Re: 67 exhaust manifold

Joseph,

For a non-AIR 67 base engine car, the numbers in the latest judging manual are 3846559 left side and 3747042 right side. There is also a 3846559A for the left side, like mine:



Here's the right side on mine:



Would be interested to know if anyone with a 67/327/300 HP original engine has exhaust manifold bolts like the pictures below and with no French locks:





Other than removal of two bolts on my exhaust manifolds ( for the Vintage Air system), my exhaust manifolds have never been off the engine since I got it secondhand in 1968. It never had French locks, but it has these unusual exhaust manifold bolts with a flanged head and odd threads. I have brought this matter up before. I still get dinged for no French locks, but I just smile and take it, because I know that that is how the car came to me.

My 67 base engine car is fairly late (22049, June 30 assembly with a 6/26/67 flint engine.

[John H.]

Re: 67 exhaust manifold

Would be interested to know if anyone with a 67/327/300 HP original engine has exhaust manifold bolts like the pictures below and with no French locks:





Other than removal of two bolts on my exhaust manifolds ( for the Vintage Air system), my exhaust manifolds have never been off the engine since I got it secondhand in 1968. It never had French locks, but it has these unusual exhaust manifold bolts with a flanged head and odd threads. I have brought this matter up before. I still get dinged for no French locks, but I just smile and take it, because I know that that is how the car came to me.

My 67 base engine car is fairly late (22049, June 30 assembly with a 6/26/67 flint engine.

Jerry -

Those exhaust manifold bolts look like the tri-lobular self-locking bolts Joe Lucia has described that were used on some big-blocks. My '67 327/300 engine was built on June 8th, and had ordinary bolts and french locks.

[Joe L.]

Re: 67 exhaust manifold

Hi Michael,
I have a 1966 327 california car (A.I.R.) The block was replaced along the way with a 3970010 cast block. I believe both blocks were 325, 350HP. The current block has the 3872778 RH exhaust manifold, but the LH has an exhaust manifold cast 3872786 also with A.I.R. holes. I am told that the LH should be 3872765. Does anyone know if the 3872786 LH manifold could be correct for the 1966 327 350HP or when it was actually used. I have search the internet but can only find a little about this manifold. Thank you for the help.

Jeffrey-----


As far as the 3872786 manifold goes, there never was any such manifold. I expect you're reading the second to the last digit incorrectly. This is very common with casting numbers.

As far as the 3970010 block goes, that block was only used for 350 and 302 cid engines. The only way it could be a 327 is if either a 1968 327 crank was installed in it or if a specialty, aftermarket crank was used. I doubt either. I expect what you have is a 350 cid engine. Depending upon internal configuration it could be anything from about 250 hp all the way to 370 hp. The block stamp pad suffix code, if there is one, will likely "tell-the-tale".

[David L.]

Re: 67 exhaust manifold

I believe that the "3846559" L/S manifold was used on 1964 models while the "3846559A" L/S manifold was used on 1967 models.

In my notes about exhaust manifolds I show a "3846559A" L/S manifold dated "E25" (May 25th) and a "3747042" R/S manifold dated "E24" (May 24th) as original equipment of a 1967 Corvette. It seems that the it was common not to have the year in the casting date.

I have no idea when the "A" was added on the casting number.

In my collection I have the following:
3846559A, LH33, K25 (Nov. 25th)
3846559A, LH2, SCC, 1-28-76 (service manifold)

Dave

[Jeffrey M.]

Re: 67 exhaust manifold

Thanks Joe,

I took another look today and used a crayon and paper to transfer the cast number to paper. This method really helped to see the numbers. I do have the correct 3872765 manifold, but never would have known it by just looking at it. It really looks like an "86" without the image transfer to paper. I believe my confusion started when I googled the incorrect 3872786 number and found www.mamotorworks.com having this exhaust manifold available for sale.
Anyways, thank you very much for your suggestion