C3 69 L46 350 smog tubes

[Jimmy B.]

When I removed the smog tubes from my 1969 350 exhaust manifolds I noticed very small diameter washer/orifices with holes in the center that seated up to the tips of my tubes when they were tightened up to the manifold. Can I remove these small orifices and just leave the hole opening wider where the end of smog tube seats into the exhaust manifold or will this cause a problem? My reasoning is that the system would now breath better with a wider opening. Is there a problem doing this?

Regards,

Jim Blakely

[Michael B.]

Re: C3 69 L46 350 smog tubes

The system works by injecting additional oxygen laden air right behind the exhaust valve. Unburned exhaust gasses are hot enough there to burn with the additional oxygen.

These tube are a special nickel material and cost about $125 a set. Leave them in and let the system work like it was designed. If you remove them you may find that the exhaust pressure is high enough to burn up the check valve and hoses. Sending exhaust into the pump will cause it to sieze in short order too.

I think you are better working on your reaction time or removing the AIR manifold and tubes, and plugging the holes...which is illegal here in California, even though 1969 cars are not tested. I don't think you are going to find any performance gain by removing them.

[Joe L.]

Re: C3 69 L46 350 smog tubes

The system works by injection additional oxygen laden air right behind the exhaust valve. Unburned exhaust gasses are hot enough there to burn with the additional oxygen.

These tube are a special nickel material and cost about $125 a set. Leave them in and let the system work like it was designed. If you remove them you may find that the exhaust pressure is high enough to burn up the check valve and hoses. Sending exhaust into the pump will cause it to sieze in short order too.

I think you are better working on your reaction time or removing the AIR manifold and tubes, and plugging the holes...which is illegal here in California, even though 1969 cars are not tested. I don't think you are going to find any performance gain by removing them.

Jim and Michael-----


Yes, I would definitely leave the tubes in place. What Jim is seeing as the "orifice" is actually the end of the tubes which serve as the seats which the tubing nuts on the "trees" bear against. These "trees" are not designed to and will not seal without the tubes in place.

Also, it's illegal EVERYWHERE to remove or disable any part of an emissions control system since it's in federal law, not just state law. Beyond that, though, I would never, ever remove an AIR system, anyway. In fact, I plan to have a fully functional AIR system in place on my "ZL-1". I have found that without an operational AIR system on my 69 (which once occurred when an AIR pump froze up on me and wiped out the belt when I was out on the road), the unburned hydrocarbon fumes in the cockpit were VERY NOTICEABLY increased, especially in top- down driving. The car was MUCH more pleasant to drive with the AIR system functioning, especially since everyone these days, myself included, is much more "sensitized" to hydrocarbon fumes since modern cars don't emit much and we're no longer "used to it".

ALWAYS ensure that the CHECK VALVES in the AIR system are functioning properly. If they're not, the exhaust gasses will definitely revert into the pump and diverter valve and ruin them in short order as Michael mentions. Original diverter valves are not something you want to have ruined. Keep in mind that the "reproduction" check valves on the market with the "must have" correct part number stamping are usually re-plated, USED valves. These valves are life-limited, so when you get a USED piece, a good portion of its life is already "used up". Who knows how much is left? Now, wouldn't someone be "distressed" if they ruined an original diverter valve just so they could have part number-stamped check valves on their car?

[Jay G.]

Re: C3 69 L46 350 smog tubes

... Keep in mind that the "reproduction" check valves on the market with the "must have" correct part number stamping are usually re-plated, USED valves...

Joe,

I am just about to take the plunge on a complete system for my late '69 BB.

Do you have any recommendations for "functional" replacement check valves that are still available new from GM?

Regards,

Jay

[Joe L.]

Re: C3 69 L46 350 smog tubes

Joe,

I am just about to take the plunge on a complete system for my late '69 BB.

Do you have any recommendations for "functional" replacement check valves that are still available new from GM?

Regards,

Jay

Jay----


There are many choices for NEW check valves. The GM valve for your application is GM #22050642, aka Delco #214-422. However, this valve GM lists for about 45 bucks, probably less through Delco. This valve is configured very much like the original GM #5361992 EXCEPT instead of being zinc plated with a chromate over-plate, it's powder-coated black.

You could also go with a Standard Motor Products AV-7. This valve is configured a little different than the originals, particularly the configuration of the valve chamber. However, it's zinc plated with a chromate over-plate more-or-less like the originals. I believe this valve is also sold under Airtex #1A3000 and Echlin #CRB22900

Then there's Borg Warner #CV8. It's configured pretty much like the Standard Motor Products piece except it's painted black.

Now, some might say that these valves are all of the same manufacture and are all the same. However, if so, how come the GM/ACDelco piece is configured differently than the others and is finished differently than the others? SOMETIMES parts are the same (as in the case of the Standard Motor Products, Echlin, Airtex, and, likely, Borg Warner pieces here). However, sometimes they're NOT the same.

Pictured below are photos of an NOS original GM #5361992, a GM #22050642/Delco #214-422, and a Standard Motor Products/Echlin/Airtex piece. Also notice that on the original valve and the current GM valve, the crimp is on the threaded fitting (outlet) side of the valve. On the Standard Motor Products/Echlin/Airtex valve, it's on the hose nipple (inlet) side of the valve.

[Joe L.]

Re: C3 69 L46 350 smog tubes

...and here's the Borg Warner valve CV-8. So, the choice is yours (except for my NOS GM #5361992 valves; they're not for sale).

[Jay G.]

Re: C3 69 L46 350 smog tubes

Thanks Joe.

Do you have any information on the reproduction "correct" valves from Paragon and others? Are they just the old replated valves you mentioned above?

[Joe L.]

Re: C3 69 L46 350 smog tubes

Thanks Joe.

Do you have any information on the reproduction "correct" valves from Paragon and others? Are they just the old replated valves you mentioned above?

Jay----


As far as I know, these are re-plated, USED valves. These valves are actually not that difficult to find and "harvest" in salvage yards---they were used on a LOT of GM vehicles for many years.

[Jay G.]

Re: C3 69 L46 350 smog tubes

Joe,

Thanks again. This is great information to have.

Jay

[Jimmy B.]

Re: C3 69 L46 350 smog tubes

Thanks everybody that chimed in. I have dug those 8 orifices out of the top drawer of my tool box and am re-installing them.

Now that I have purchased a correct 11 in. clutch, ordered a correct 608 waterpump with small front hub and proper bolt spacing and got my smog parts sorted this engine will soon be installed in my 69. I just downloaded Duke's April 1st 2006 article on installing my distributor and achieving proper orientation so it looks like i am just about ready to go. One thing I did have to do was omit that o ring washer on the front exhaust manifold mounting bolt (the one with the stud the ac bracket mounts on) because with this additional spacer installed my bracket was not aligning properly with my other ac bracket to align the mounting bolt. When I eliminated this washer/spacer all aligned perfect.

Thanks again.

Jim Blakely