Did I do this right? Mixture adjustment.

[pbs911]

Finally broke down and picked up a Gunstun Gastester. I followed the directions and found I the CO level on my 78SC was at about 15.00. Perhaps this is the result of the idle "hunting", duh. If you don't have one, get one. The process is simple.

Anyways I adjusted the CO level to 7.0 at idle (950 rpms). The car runs great, no hunting and good throttle response.

I just spent an hour doing a search but could not find an answer to my question. Is the CO level on a 78SC supposed to be 3.0 + .5? Will the 7.0 at idle get me past smog in CA? I thought I read that JW recommended a CO reading of 7.0 at idle for best performance because the mixutre will lean out with an increase in RPMS. Should I go down to the 3.0 for smog test purposes and then reset at 7.0? The car has pre-74 exhaust. The air pump is not installed.

Any help is appreciated.

[targa80]

I don't have the gas tester, so I resorted to the use of a Dwell meter on the test connector to adjust the fuel mixture to eliminate the hunting at idle. Had to take the car to the special CA smog test site (not just any smog shop). They hooked it up to the machine and ran it . They told me that for an 80 automobile I was dead nuts on the specs and passed with flying colors. I have read a lot of post about disconnecting the O2 sensor when the engine isn't running just right but that will just force the Lamda system to go to a default rich mixture which I am sure would never pass a smog check.

[pbs911]

humm, slow board today.

Targa88: Thanks for the response, but my car did not come equipted with the O2 sensor. It's my understanding that the CO levels on cars with the O2 sensor should be set a little lower.

Well I spent about 2 hours reading evey post on the subject that would turn up. But I still can't find JW recommendation regarding a 7.0 setting. Perhaps I was high that day.

It seems that the factory CO level is set between 1.5 - 3.5. This thread is a good discussion and suggests about 1.5 - 2.0 for the most performance. Anyone tried this and found beneficial or adverse effects?

[john walker's workshop]

the 7% thing is for MFI engines. yours will run best at 3-3.5%, but may need to be a bit lower to pass the test, depending on your state's requirements. 7% on an SC should cause idle and driving surging. way too rich!

[pbs911]

Thanks John.