anyone know the factory spec for settin the CO on the FE 390?

 

CO? Please elaborate a little more....G.

 

Percentage of carbin dioxcide

 

Oh I have no idea sorry. Is this for emissions testing?

 

"CO" is carbon monoxide. "CO2" is carbon dioxide. Both are so-called "Green House" gases and are affected by how rich/lean your fuel settings are. Richer - more CO/CO2. Leaner - less CO/CO2. Just adjust your carburetor to the factory specs and you should be OK. At a gross level, fuel economy affects CO/CO2 hence the efforts by certain states to regulate fuel economy (currently set at the Federal level) by limiting CO/CO2 emissions.

 

Yes, that is what I need to know. no longer have the stock valve covers that had the sticker on them and the shop manual does not give the spec so that is what I am trying to find out.

 

I have listings and settings for 64-70 carbs, timing etc... if that's any help.

 

The shop manual will tell you how to adjust the idle speed and idle mixture settings. These are what affect CO/CO2 emissions (assuming the test is a static, idle test only). If you make these adjustments and then measure CO/CO2 (that would be specified by your state emissions check station for your year truck) you can fine tune things with the same adjustments. Just setting the idle speed and mixture per the shop manual should get you where you need to be as long as there are no other problems with your engine.

 

Careful with generalizations about CO - too lean will also give you higher CO levels if you go too far. CO is a by-product of in-efficient burning - too much or too little fuel will give you higher CO.

HC (Hydrocarbons) are directly affected by rich or lean - richer=more HC, leaner=less HC. CO is lowest somewhere in the middle, right where the burn is perfect.

I wouldn't worry too much about matching a specific spec from Ford - get it to the lowest possible at idle, that's where the burn will be perfect. As for open-throttle CO emissions, who knows? If you really want to be on-the-money, get an air/fuel guage with an O2 sensor, tune for best mix and likewise, the CO will be lowest.

I had a Triumph TR7 with dual 2bbl Weber 45mm DCOE's - FOUR idle mix screws! Never could get the thing to run perfectly at idle. Until the day I had to get it inspected, and it failed on emissions - the guy let me fool around until I got the setting at it's lowest, and it passed. And from then on, it idled great.

art k.

PS: Had my '74 F250 idling near the garage (12 feet away) with my 390 in it. The exhaust wasn't even pointed at the garage. Within 15 minutes, the CO level in the garage was 650ppm (I have a detector), which can KILL in 45 minutes. Needless to say, I had the typical flu-like symptoms of throwing up, red face, etc. My wife just thought I drank too much

 

Well I guess everybody is like me, no emission decal, I will just have to get it down below the state requirment. Just was hoping I could come up with that setting so I could try it there as I have an exhaust gas analizer. Thanks to all who answered my post.

 

What year vehicle? As stated, tune up specs will do what you need.
Mike

 

True. I wasn't trying to get too scientific. The main point as you agree is to set the carb to factory specs (idle speed and mixture) and you will be pretty darn close if not dead on. Then you can tune from there with the exhaust gas analyzer/O2 sensor.

 

From the factory, for FE engines, I believe if there was a listing, it was not for CO but rather for CO2 and it was used for setting the carb to emissions standards with test equipment that injected CO2 into the carb/intake manifold. It was not listed for tail pipe emissions and would only have been found on 72 and later models and I think it was only on early Duraspark models.

I think that is the deal, I might be wrong. So finding valve cover information will do you no good without the C02 injection equipment. I think they might have used propane for this too.

 

Hi:

I don’t know if this will help, but there is a sticker on my driver side window on my 72 F250 that has the California Exhaust Emissions information on it for various truck engine sizes, and the listing for a 390 is:

HC = 141
CO = 0.52

I see that you are in Arizona, and may be their specs are different.

I hope that this helps.