Exhaust manifold question.

[oleguy]

Some stock cast iron exhaust monifolds have a copper tube in the exhaust port, and some don't . Can someone tell me what this is for? I am talking about Chevy ramshorns from the 50's, 60's and maybe into the 70's. Thanks oleguy

[FirstOwner69]

Passenger side manifold? If so, it's for the choke warm-up as shown in this picture of my 58 Corvette.

[oleguy]

Thanks for the quick answer, however this is not the tubes that I am asking about. There are four tubes in each manifold, one in each exhaust port. they look to be about 3/8" dia. Both rite and left side have them.

[cooperhw]

I don't think they are copper. They are for smog.

[michael bustamante]

yup those are most likely from a 70 veh and are for emissions. most people remove them and put a screw in cap plug

[swamp rat]

Exhaust air pump? I had one on my old Toyota that injected air into the ports to lower emissions.

Truth is i have never heard of this kinda stuff on the earlyer years you mention but i could be wrong.

[oleguy]

Thanks for the info.

[TBONE1964]

To be more specific it is for an "air" system which is short for air injection re circulation. It uses a belt driven pump on the front of the engine and plumbs piping into the exhaust manifolds. This forces fresh air into the exhaust to help reduce emissions.

It was more common on early vehicles (late 60's, early 70's) with California emissions. As time passed, most of these equipped vehicles had these systems removed and scrapped because of pump lock up.

If you buy some aftermarket rams horn exhaust manifolds, they will be made to except the "air" tubes and come with plugs if the system is not being used.

Hope this helps answer your question.
Tom