I just recently cracked by cylinder head on my 89 I6. I was searching for some prices and there is a head with the AIR system and the head without. What is the difference and how do I know if I have the AIR? Also if anyone knows of a place to get a good head cheap, it would be greatly appreciated because I think one could be had for less than $399.

Thanks
Pete

 

The AIR fittings refer to the pipe fittings for the smog pump system. Some had them in the intake, others in the head, and older ones didn't have them in either. If yours' has the long pipe with the fittings screwed into the head then that's the AIR fitting type. The fittings are 1/4" pipe thread if I remember correctly. If your truck has the fittings in the intake, then you can use a head with the fittings, just plug them with pipe plugs available at any hardware store in the plumbing section, or at any REAL auto parts store. If you need one with the air fittings, I know that here in middle Tennessee, they are harder to find. I looked at every junkyard I could think of and they had the heads without the fittings, but not the ones with. I'd about given up when a customer told me about a junkyard called Smith's, near Clarksville that had a Chevy head he couldn't find anywhere else. I called them and they had one. It was $225, but they re-worked it too and it's been trouble-free for about 40,000 miles now. I see them on ebay often, but if you get one of those I'd figure on letting a local machine shop check it out before I tossed it on.

 

The AIR bungs are 9/16-18UNF thread not 1/4"NPT.

 

Thanks for that correction. I couldv'e sworn they were 1/4" pipe, but it's been a while since I had mine apart, and I didn't plug them. Maybe I should ask in the small block forum, but do you know the thread size for the tubes on a 351W? (back of the heads). I'd like to get everything I need to install headers/exhaust soon, and have it ready before I start, as it's my daily driver now.

 

There must be different sizes because i just put 1/2"-20 x 1/2"long socket headed set screws in mine.

Try Ebay for cylinder heads there is always a complete rebuilt head on there for about $325.00