Exhaust Manifold Smog Holes ??

[John Brown]

Did several searches and came up empty. I seem to remember someone asking who machines non smog manifolds to accept the smog stuff. I have a friend that need it done to his big block manifolds. Any help would be appreciated. Thanks.....

[Chevy454]

How about I just swap him a set *with* the holes?

[John Brown]

Thanks Rob, but.... he wants his done cause they're date coded to his car?? Already tried that but it was a "no go".

[Chevy454]

Bummer...he posseses the hardest ones to find, then!

[nuch_ss396]

Hi John,

If it's the one I'm thinking about, I was the one that
started that thread some time ago. Here's the link.
Let us know how you make out here.

Steve

SMOG port machining topic

[SS427]

Most any reputable engine machine shop will do these for you. I brought my manifolds to my engine builder along with the tubes so that he could use them for measurements. $100 and one day later they were done.
Rick

[427king]

Rick while its true any machine shop can drill the holes not too many can or know to drill the "step" so that the smog pipe will slide in and fit properly,its not just simply drill a hole and your done.The tubes have an angle so they seal and its also a special tap. If you look at the hole from the backside of the manifold it is smaller than in the front. Ive actually had all the machining and tools made up and can have these done to perfection for 80.00 a pair for members only. Not trying to make a buck off this post, but ive seen so many done improperly just so as the pipes would fit,yet there was no angled lip for the short inner pipe to seal against. I guess you can just drill and tap a hole if your not using the inner pieces and that will work,but it really isnt correct or complete. The other issue is alot of times ive seen redrilled manifolds have the holes off center, and also have seen some where the pipes actually didnt fit because the holes[angle] were off just enough. thats a big problem on a set of 1500.00 manifolds

[Hotrodpaul]

I can do them for you. I currently have several SB manifolds with smog but no BB versions. If you could send a comparable or scrap BB manifold with smog holes I will design a fixture on my Bridgeport Mill to correctly machine the ports. PM me for more details.

Paul
713-306-1892

[nuch_ss396]

[ QUOTE ]
Rick while its true any machine shop can drill the holes not too many can or know to drill the "step" so that the smog pipe will slide in and fit properly,its not just simply drill a hole and your done.The tubes have an angle so they seal and its also a special tap. If you look at the hole from the backside of the manifold it is smaller than in the front. Ive actually had all the machining and tools made up and can have these done to perfection for 80.00 a pair for members only. Not trying to make a buck off this post, but ive seen so many done improperly just so as the pipes would fit,yet there was no angled lip for the short inner pipe to seal against. I guess you can just drill and tap a hole if your not using the inner pieces and that will work,but it really isnt correct or complete. The other issue is alot of times ive seen redrilled manifolds have the holes off center, and also have seen some where the pipes actually didnt fit because the holes[angle] were off just enough. thats a big problem on a set of 1500.00 manifolds

[/ QUOTE ]

Chuck,

I tried to send you a PM, your box in full.....

[SS427]

Chuck,
I typically bottom drill them with no through holes and make the smog pump inoperable when the customer desires them this way. I have had no ill effects from this and still get the looks without the function. Drilling them with the step would not be difficult with the correct cutter if someone desired them to be functional.
Rick