I need some help determining if it is a "big deal" or "no big deal" adding (drilling&tapping) smog tube holes to a cherry set of exhaust manifolds. Found a nice set with correct date code but no smog tube holes. Advice and help please!
:beers:

There are plugs of the same thread, straight thread, 3/8-16, not a pipe thread.

I need some help determining if it is a "big deal" or "no big deal" adding (drilling&tapping) smog tube holes to a cherry set of exhaust manifolds. Found a nice set with correct date code but no smog tube holes. Advice and help please!
:beers:

Very Hard to do. Not only are they tapped but there is also a small boss that is end milled? for the tubes to seal against at the end of the threads inside the manifolds. It could possibly be done but the cost might be more than a set of repo manifolds. IMO.

Give it time while looking for what you need.

They can be re-skined and will look like new.

I totally misread - you would like to put IN smog connections. Inverted flare - look at end of a 3/8 inch flared fuel/brake steel tubing - this is the configuration in the hole.

Plus, don't forget the the flare ID has to smaller to fit the spray nozzle before the smog tubing goes on, or at least later years has this configuration.

Only problem I have with repo manifolds, have they been stress-relieved to prevent cracking at a later date?

I need some help determining if it is a "big deal" or "no big deal" adding (drilling&tapping) smog tube holes to a cherry set of exhaust manifolds. Found a nice set with correct date code but no smog tube holes. Advice and help please!
:beers:
Chick,

Lots of people would love (*prefer*) to have your manifolds without the smog holes; ones with smog holes are surely more readily available? I'd offer to trade them for good ones the way you want them.... Just a suggestion!

You may want to check the thread as I believe it to be 1/4 straight pipe thread not taper pipe.Jeff

I'm certain it's a straight thread. It is intended to seal on the end of the extension tubes, rather than seal on the threads like tapered pipe does.

You may want to check the thread as I believe it to be 1/4 straight pipe thread not taper pipe.JeffYes, you're right, my mistake. Its 1/4 inch verses 3/8 inch flare nut, meaning straight thread.

Chick,

Lots of people would love (*prefer*) to have your manifolds without the smog holes; ones with smog holes are surely more readily available? I'd offer to trade them for good ones the way you want them.... Just a suggestion!

Gary, the set I was just checking on adding smog holes I DO NOT own. They were cherry and considered purchasing them if I knew of a process to add the smog holes. Man I've had a hard problem finding correct dated ex. manfolds. And the only thing I have to trade are smog holed as well. Do really appreciate the offer though...... :thumbsup:

You may want to check the thread as I believe it to be 1/4 straight pipe thread not taper pipe.Jeff

That's correct - they're 1/4"-18 National Straight Pipe Thread. :)