Taking the plunge.....

[CyberVette81]

OK I finally decided to do it. I found a mechanic who will take off all of the smog/emissions junk off my '81, install hedders, remove cat, and install true duals. My question is how will this effect the computer control module? Do I need to make some sort of adjustment to the carb? Can I expect the car to idle and run good with the smog stuff removed? I was looking at the Hedman ceramic coated hedders with flowmaster 50 mufflers. Anyone have luck with that combo?

 

[SG4206]

I believe you are stepping off into the trial and error part of your life.
My opinion is to put the oxygen sensor back in the system, and you shouldn't have any problems. If you do have problems , put the EGR back into the system.

Good luck.

 

[81 Corvette]

for the carb and distributor to work properly, you will need to hook the O2 sensor back up. Or you can put on a non computer carb and distributor. Thats the route i went.

 

[Jack]

for the carb and distributor to work properly, you will need to hook the O2 sensor back up. Or you can put on a non computer carb and distributor. Thats the route i went.

As per 81 Corvette ... your 81's carb & distributor & O2 sensor rely upon their computer ... all 4 work in concert. For good performance without a funtional computer, you'll need a different carb & dist ... like those found on 75 thru 80. Otherwise, leave the emissions stuff & O2 on there and fix what needs be. If you need a new pre-computer HEI distributor ... I have one for sale ... email me if interested. Before you start yanking stuff ... Do verify you won't have any government emissions inspection issues in your locale ... how & where regs are enforced varies greatly.
JACK:gap

 

[81 Corvette]

you can add an O2 sensor to the headers, you will have to drill a hole in the collector and attach some threads

 

[CyberVette81]

Thanks for the input guys. I'm wondering if I leave the emission stuff on but just disconnect the smog pump if that will work out ok. As I understand, the smog pump takes a few horses away because of the belt that drives it. Is that correct?

 

[Vettehead Mikey]

Yes it takes a horsepower or two away, not enough to be noticeable in real world driving.

 

[Mac]

Putting an oxygen senser into an exhaust system with headers isn't a problem. If your engine management system included an oxygen sensor, you definitely need to put one in. I believe some headers have a port for the sensor built in. If not, the usual method is to weld a nut onto the exhaust pipe just behind the headers and then drill a hole inside the nut.

-Mac

 

[81 Corvette]

Thanks for the input guys. I'm wondering if I leave the emission stuff on but just disconnect the smog pump if that will work out ok. As I understand, the smog pump takes a few horses away because of the belt that drives it. Is that correct?

When i first bought my car, i took the pump out. In hindsight, i think it ran better before removal, although it could be cause my car is possessed. I'd just leave it hooked up since it uses very little power. whats 2 horses on a 190 hp motor.

 

[chevyaddict]

I take it you don't have emissions where you live? You lucky dog! I can't STAND emissions......... UUGGGHHH!!!

 

[CyberVette81]

Yea I'm lucky, no emissions testing where I live.

 

[Dave L.]

No emissions...

I have true duals with no emission items (egr,air pump,etc.) with no check engine light or drivability problems what so ever. No adjustments were made to the carb. As mentioned you'll need to have an operational O2 sensor,MAP sensor (manifold air pressure) and coolant temp sensor (the one in the intake). The only variations from stock are an Edelbrock 2101 intake and the true dual exhaust. The car runs absolutely superb.


Dave