Kyle Karbum

Trying to get this Cherokee back to stock mixture.

The previous owner took out a bunch of the emissions gear, had the timing 18 degrees advanced from stock, and the factory sealed mixture screw was hacked opened and set rich.

1986 Jeep Cherokee 2.8L v6
Varajet II E2SE Carburetor

Does anyone know which direction to turn the screw to lean it out?

I found the service manual for the 2SE online, slightly different model, and it gives directions on how to get the optimal mixture but it also says that from the factory these carbs were set on the lean side. And it didn't say which direction to lean it out. Need it lean to pass smog.

I guess I could mess around with it a bit and eventually find which direction is lean by smell but knowing the direction to turn would just be much easier.

Anyone got any experience or advice?

EZEARL

I've always used a vacuum gauge hooked to a manifold vacuum port(brake booster line will do). With engine at operating temp set the idle up to about 1500rpm(fast idle). Adjust mixture screw/screws for highest vacuum reading then turn ccw 1/8th turn. For a lean mix turn screw/screws 1/8th turn cw. Do the adjusting SLOWLY giving the engine time to react to adjustments. Set idle down to spec.

Kyle Karbum

Sounds good. I was guessing it was cw so I'll consider it confirmed. Thanks for the info.

Now lets just pass smog already. Then I can move on to welding the cracked exhaust manifold and replacing the opposite side gasket. Always more fun to be had.

Kyle Karbum

A few more questions I have though they might be tough to answer.

The carb service manual said the mixture on these carbs was not perfectly optimal but set intentionally a bit on the lean side.

How many turns cw past optimal do you think they would have set it at the factory?

79 ppm HC at 25mph is the only part of the test it fails on. On a test where I had to wait in line(not fully hot), it was 14 over, and on a test that I got right off the freeway, it was 86, only 7 over.

How many turns cw do you think it needs to lose just that little bit of HC?

DFlintstone

I know Earl knows things and don't mean to conflict. I did have a California Smog License. I forget..it expired 81 0r 83.

"the factory sealed mixture screw was hacked opened" Good! Cursed things. They put the plug there so the average idiot couldn't mess it up. Give even a monkey a screwdriver and 10 minutes.....

At temperature with the idle where it goes, back the mixture screw out till you are sure it's too rich. Around three maybe. Now you go in (clockwise) slowly and listen. What you are looking for is "lean roll". That is the engine telling you it does not have enough fuel. From there go back, (richer, counterclockwise), 1/4 to 3/8 a turn. (Btw if you can't kill it with the screw,(s), there is another problem)

Btw on a 4 barrel and such with two screws, you go back and forth, also idle might be reset as you dial it in.

Optimum timing is different for about any engine. Yours probably would like 8* advance at idle, regardless of the spec. For optimum timing, with the fuel/octane you use, at temp, accelerating from 30 to 50 you want only a "ghost" of a "ping", (predetonation). I start so advanced it knocks, then back it off, (retard) the the timing until that just quits. You might luck out and get more than a little over 8* If your rotor turns clockwise, turning into it, counter clockwise, advances the timing.

Unless you want to ride under the hood while someone gasses it up towards 50, or have a van with a dizzy you can turn while driving, it takes allot of starts and stops to get the timing perfect.

If the shop that installs cats is across from the smog shop, just go straight across the street!

DFlintstone

If it's so lean it misses or stumbles, your HC, (unburned fuel), will shoot up.

Long story, but run some Chevron Premium for a while. Use no additives.

I've never actually "de'carboned" with water. Also not sure what that might do to a cat. A small trickle of water flashes to steam and will dislodge carbon deposits. It's a proven old trick, no BS. I just mention it....getten a carbed 86 through smog, you want all the weapons! (google or utube the water thing, less is better, (like a small Dawn bottle....

EZEARL

Never had to deal with smog tests THANK the Lord.

DFlintstone

I remember when I was 4 in about 64, living downwind of LA, (Pasadena), and not being able to take a whole breath. 1/2 way your chest would "clinch". Akin to trying to down a cup of vodka. The body just rejects what you are trying to do, but breathing in this case.

EZEARL

LA has been known for many decades both nationally and probably internationally for its smog. I grew up in Baltimore City near Curtis Bay. Fumes from the refineries,paint manufacturing plants,etc were unreal. Plus everything including our row houses up until the mid 50's was coal fired. I had a friend who was a premed student at Johns Hopkins back in the early 70's. He was involved in an autopsy on a 10 month old inner city baby. Don't remember the cause of death but she had dime size spot in one lung.

ajpulley

You might also consider advise from early Chevy S-10/ GMC S-15 owners. I had an early S-10 years ago when I lived in Cal, and it had the Rochester Varajet E2SE, which I believe was the version with the TPS and mixture solenoid. The 2SE was for non-Cal states. I had a hole in the top screen so I could insert the jet adjustment tool at any time. If I remember correctly, the float also had to be adjusted by bending the metal arms to sit in the bowl correctly when I rebuilt it. I never could get it just right. I HATED trying to get the vacuum brakes set with that goofy degree tool with the built-in level bubble.

Just a thought.

DFlintstone

Aj's post got me thinking I may have spouted off too soon. "Varajet?" Does that mean we are talking about the main "Jet", (orifice) being adjustable? I waz talking about old school idle mixture screws.

ajpulley

I assumed that was what you were talking about. Its located beneath the rectangular raised vent stack screen on the top, just next to the stud that the filter housing top screws to. To adjust it, there is a tool that has an oval-shaped hole in the tip. This is a picture of the tool set I used to have.