1968 Stock 289 Exhaust manifolds

[retroman99]

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]

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]

It's my understanding that starting in 1966 all small block heads had the notches.

 

[retroman99]

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

 

[CougarCJ]

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]

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

 

[retroman99]

thank you this helps a lot

 

[robert campbell]

I have two early manifolds without notches if you want them. Free and you pay for shipping.

Rob

 

[retroman99]

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