I am having trouble passing emissions.. Again. Failing in the CO department. All the other numbers look good.
Anyhow, I have adjusted the valves, have the timing set to 10 btdc, the float is about 1/3.

The motor is a 1976 2F that has been desmogged. Running a header, a Jim C rebuilt carb, and a non-USA distributor.

My dwell is in the 28 degree range, and I can't for the life of me figure out how to change it to the 39-43 degree range. I have the non-usa Points distributor. I also have a dwell meter. Points gap is .018. But the dwell is STILL at 28 degree's.

I can locate the screw to change the points gap, and I think that the other screw is the one to change the dwell, but I am not 100%, and no matter how much I fiddle with it, I can't seem to change the dwell.

Could someone please shed some light on this?

I could never set my dwell on my non-usa distributor correctly neither, so I got a pertronix ignitor that made it ran nicely but the pertronix unit did not fit well with the non-usa distributor. I've just gotten the Mel's ignitor from www.jtoutfitters.com this unit fitt very well in the non-usa distributor even it costed a bit more.

/td

James, now that you're up here transfer your registration up here. No smog ;)

CO is a carburation problem: running rich. If it was an ignition problem, HC would be high.

Does the fuel drain out of the bowl after it sits overnight? If so, the carb is siphoning.

Does fuel drip out of the angled brass vent tubes at the top? If, so, the float or needle valve isn't working.

If it fails only at idle, adjust your idle mix.

If you live over 6,000 ft and you are failing at over 1,500 RPM, you might want to try smaller jets.

Can't help with the dwell but emissions here in Colorado can be a #%$@! I have worked way too much on my trucks and have fought the emissions people too many times to count. My solution....adjust timing to factory specs or slightly retarded, replace the plug wires even if they aren't that old (believe me, this makes a huge difference), change your oil, drive on the highway for 30min and go directly to the testing center, and last but no least, add a bottle or two of HEET fuel deicer (isopropyl alcohol) to the tank. Seems to burn a little hotter and will guaranty a pass. I left out the standard tune up stuff so don't ignore any of that but though I should mentioned the odd things that I found out over the years. Try to get an 85 S10 to pass as a V6 2.8 with a 350 V8 in there....and yes, I saw the light and sold the Blazer and used the money to buy parts for the Land Cruiser.

Originally posted by Pin Head
CO is a carburation problem: running rich. If it was an ignition problem, HC would be high.

Does the fuel drain out of the bowl after it sits overnight? If so, the carb is siphoning.

Does fuel drip out of the angled brass vent tubes at the top? If, so, the float or needle valve isn't working.

If it fails only at idle, adjust your idle mix.

If you live over 6,000 ft and you are failing at over 1,500 RPM, you might want to try smaller jets.

No, the fuel doesn't drain out overnight.

No, fuel doesn't drip out of the angled brass vent tubes.

Not failing at Idle. We are supposed to do it at 2 separate rpm's.
Now that I am looking at the results, they didn't change the RPM's. Test 1 was at 1578 test 2 was 1514... I think they are supposed to do it at 1500 ish and 2500 ish...
Andre I lived in park city for about 2 weeks, and found out that the cost of fuel for me to drive to and from Salt Lake every day was too much.

Bummer man, sorry we lost you :(

Good luck with your smog!

You might try smaller jets. Give Jim C. a call since he did the rebuild.

Dwell is set by the point gap. I cant remember if larger gap = larger dwell or the other way around. I think larger = larger but check it both ways. The "book" setting is only a guide. A dwell meter will set you in the right direction. I usually find I need a much tighter setting to get it right. I always shoot for 41' or so. There is a set screw with a couple of small slots near it. Slightly loosen the screw then use a screwdriver to move the gap in or out as needed. I really doubt this is your issue with the smog. Follow the advice of PH. He has set me right more than once, even when I did not want to be set right!

Well, I got the Dwell set correctly, then I found out that the truck was missing on one cylinder.. :mad2: So, I replaced the plugs, still missing. :mad3: Now, I get to replace the wires...

I am now also going to put a pertronix electronic ignition in...
:mad3: :mad3: :mad3: :mad3:

Don't sweat the small stuff.

As long as you don't have compression issues, the miss is either a bad plug, wire or distributor cap. The 2F is a tractor engine that rarely revs above 3,500 (at least for long). It is going to run fine over a broad dwell range. Just set the points at .017 and fuggedaboutit.

You still need to fix your CO problem and it isn't the ignition.

I think I figured out why I am getting such high CO numbers..

The Idle mixture screw was 12 turns out (yes, 12 complete turns). Lowered it to 4 turns out, now it doesn't start as easily.. :(
Checking the wires tomorrow. I had just been working on it for 12 hours straight, and needed to stop.

-James H.

I agree with PH about the dwell not being that big of an issue but once it is correecvty you can move on to the next symptom. 12 turns out?! I did not even think it would go out that far. Go back to the book and re do all the setings to stock then follow normal tune up process.

If you were only 10% over on CO, it might be the idle screw, but it has relatively little effect at 1,500 RPM. Stock ambient setting is 1.5 - 2 turns out and then you set it according to the "lean drop" method in the book. Basically you adjust it to max idle speed and then back in until the rpm starts to drop.