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1968 Stock 289 Exhaust manifolds

retroman99

Well-known member
Joined
Mar 15, 2003
Messages
190
Location
Redondo Beach, CA
I have a question on the configuration of the exhaust manifolds. my search for a date correct set continues. I keep seeing sets with little notches machined next to the exhaust ports which I assume is for the smog ports. if my car did not have the smog equipment should I be searching for ones without this clearance. it seems every set I find with a late 67 or very early 68 all have this clearance. any help would be appreciatted
 

gtcs1

Well-known member
Joined
Jun 17, 2006
Messages
350
If I can help, Do you have picture of these notches. I could compare with my car, with a 289, that didn’t have smog.

gtcs1
 

Mosesatm

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Joined
Jan 18, 2005
Messages
9,010
It's my understanding that starting in 1966 all small block heads had the notches.
 
OP
OP
R

retroman99

Well-known member
Joined
Mar 15, 2003
Messages
190
Location
Redondo Beach, CA
If I can help, Do you have picture of these notches. I could compare with my car, with a 289, that didn’t have smog.

gtcs1

see the attached picture with the clearances circled in red
 

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  • exhaust manifold notches2.jpg
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CougarCJ

Well-known member
Joined
Jul 17, 2006
Messages
2,186
The intent of the notches was for the thermactor smog system. I find them on non smog engines too. It is getting tough to find a pit free, set of exhaust manifolds.
 

gtcs1

Well-known member
Joined
Jun 17, 2006
Messages
350
see the attached picture with the clearances circled in red

Checked my car, 289 auto, all original, built in april, those clearances notches are present on both sides, exactly as you show them. I can see them from the top, FWD of the port on the LH side and AFT of the ports on the RH side,

gtcs1
 

robert campbell

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Joined
Apr 10, 2007
Messages
4,321
I have two early manifolds without notches if you want them. Free and you pay for shipping.

Rob
 
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retroman99

Well-known member
Joined
Mar 15, 2003
Messages
190
Location
Redondo Beach, CA
I have two early manifolds without notches if you want them. Free and you pay for shipping.

Rob

Rob that is a great offer thank you. I like the idea of no notches as it seems it would allow for more surface area around the port and less prone to leaks. ill send you a PM
thank you Brad
 
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