i am going to be replacing a 305 with a stock replacement 350 in a 86 this weekend. i ordered headers without air tubes or o2 bung. does the o2 sensor HAVE to be on? if it has to be installed do you just drill and tap the pipes? will installing the pipes without the air tubes cause any problems with the computer?
we are not going for any performance we just want an engine that runs.

thanks

 

Hey! A fellow NC'er here!

I'm not certain, but I don't think the AIR would necessarily affect anything - but you'll have to plug the pipe going to the cat or you'll have an exhaust leak. But again, I'm not certain - wait for some else to chime in.

The o2 will affect the ECM - it looks for a signal from the o2 sensor, and adjusts timing and fuel accordingly - so the ECM will choke and spew an SES on that I'd think - and maybe make the car run poorly since it can't have a source from which to adjust from (assuming you still have CC carb/dizzy).

This will also affect your emissions, but you shouldn't have a sniff test after Jan 1 2006 (maybe you don't have sniff now - that's Yadkin county right?) But, an inspection **** will fail it since there are no AIR tubes (if he visually inspects and is a stickler for detail, as you are SUPPOSED to maintain all emission equipment regardless) - get a laid-back joe blow shop to do the Safety Inspection after Jan 1.

If going to the trouble, why not put in a 350? They are about same price. You'd really like the power increase for the same work in the swap!

 

i am in davie county. we don't have the sniffer on anything, just the safety. they turn on the lights and blow the horn.

i guess i'll put the o2 sensor in. do i just drill a hole in the header pipe somewhere down where they come together? my 85 doesn't have any of that stuff. no comp. or emissions, just a cat. so i haven't had to deal with computer controlled cars.

i know that once a car turns 30 we don't even have to pass a safety inspec. i didn't believe it until i saw the letter at the inspec. place. what is going to change jan. 1st?

 

I would imagine the headers will have instruction as to where an o2 bung can be installed - it would depend on the brand of header. I don't think simply drilling/tapping would work, as the header pipe is thin (no room for threads). I think a bung has to be welded on - an exhaust shop should be able to do it cheaply enough.

Jan 1 the NC emissions counties (like me in Wake) will no longer have the sniff test on anything pre 1996. They will do OBDII emissions inspections through the ECM on 1996 and later cars, and a simple Safety Inspection on pre 1996 cars. BUT - they are supposed to be looking visually for emissions equipment as it is supposed to remain in place. Supposed to my butt - I'll find someone here to pass it! I went carbed 350, no emissions crap, no ecm. In a few days, I'll be set free!

 

They make weld-on header bungs. They are threaded to take the O2 sensor- kinda like a thick metal collar with threads inside. You drill a hole in the header, where appropriate, then weld the bung onto the header around that hole. Then screw in the O2 and hook 'er up. Make sure you choose the location carefully so the O2 isn't pointed directly into something immovable when installed in the car.