Tuning a 2.6L

[tekjones83]

I have 1989 MM 2.6L 5 Speed Just attached a Weber 34 DGEC Progressive Carb. I have replaced the Fuel Filter next to the tank and plugs, wires, cap, & rotor. It idles a bit rough and when I press the gas pedal it stalls,skips,and pops back and until full throttle then it runs great but just for pulling off from the drive way it just dont do nothing but pop and skip. Anything I need to do please help! Any comments are welcome and take a look at the pics and see if I did sumfin wrong or I need to change something.

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[tekjones83]

distributor has not been moved out of its original position.

[camoit]

What is the timing set at. I would bet it's too advanced. Try retarding the timing just a bit and then readjust the carb. How many turns out is the mix screw? Also if you look at the manual that came with it there should be a trouble shooting guide. If not look in the manual section for my first gen manual. There is a weber guide in there also.

[tekjones83]

I have no idea what the timing is set at its stock i guess lol i heard to turn the mix screw 1 1/2 turns out and back 1/2 turn form a friend of mine but i dont know if it is true or not and when i turn the mix screw in it accelerates is that even right? I will look in my chilton manual and see.

[pennyman1]

Sounds like you are turning the idle screw - if it was the mixture screw, turning it in will lean it out and slow it down, not speed it up. It also looks like you may have the vacuum advance hooked to full vacuum, not ported vacuum. Ported vacuum is above the throttle plate; the port you have it hooked to is at the throttle plate - it will cause full advance at idle, and drop off at WOT. Find the ported vacuum port and hook the vac advance there, then cap the port you were using.

[tekjones83]

The only ports I see and is available is the vac tree on the intake as you see are capped with vac lines looped over and the carburetor only has that port that the distributor is connected to. Should I connect the distributor to one of those ports on the vac tree on the intake and cap the carburetor port on the carburetor? what is a WOT?

[pennyman1]

Give me until tomorrow to pull out my weber manuals to figure out was ports that carb has. WOT is wide open throttle. That carb is an emissions carb and should have more ports on it, but I need my manuals to be sure.

[tekjones83]

Thank you and cant wait lol sorry noob to my weber carb hahaha

[pennyman1]

Here is an install manual on the carb - it appears that is the vacuum advance port, but it seems that getting the port to work right may be tricky: http://www.racetep.com/weber/INS-WK601-34.pdf . There is a ton of info on the jeep forums about this carb and how hard it is to get tuned right. Also, this carb is not made any more, but jets and parts are still available.

[tekjones83]

Thank you and everybody for all the help this is the best site ever and keep up the great work and keep me posted if anybody finds out anything.

[Acuta73]

Stock timing I think was either 7.5 or 8.5 degrees before top dead center. You should probably be in the 9-10 degree range. Best way to find out is just play with it.

[tekjones83]

Yea That sounds right and I did play with it lol I got it close enough to where I got my gas mileage back and performing. Thanks

[tekjones83]

Does anybody know what the Vacuum PSI on a 2.6L? I heard you can tune a engine by a vacuum gauge?

[Rickdees]

You use a vacuum gauge to set the idle mixture on the carburetor. not sure how much vacuum our trucks have?

http://www.allpar.com/fix/carb-tuning.html

[tekjones83]

Thank you it helped

[74Dusted]

You use a vacuum gauge to set the idle mixture on the carburetor. not sure how much vacuum our trucks have?

http://www.allpar.com/fix/carb-tuning.html

On a fresh 2.6L (stock rebuild) in one of my old trucks, it had 23" of Vacuum at an idle. On a older engine with some miles, maybe 19 - 20" of vacuum. A higher mileage engine, 15" or so.

[tekjones83]

Sweeetnesss

[74Dusted]

Also, low vacuum is common on radical engines too. The 340 Small Block in my '74 Duster only builds about 12" of vacuum at an idle (and that's a brand new radically built engine)

[Medevack1]

im sorry for bringing up this tread form way back..... i have the same problem with my '89 shutting off, however my mechanical fuel pump has 3 nipples and one is capped off, thats how it was when i got it. Is there a reason why? It looks new, Also can i get rid of all the vacum lines except for the ign advancer now that i have a weber carb?

[pennyman1]

The capped fitting on the manual pump goes to the return line to the tank. As for the vacuum lines, only the vac advance and the booster hoses are needed to run with a Weber.

[Medevack1]

Thank you!!!! so i can disconnect all the other vacum hoses for the exception of the vac advancer and the break booster?

[DroppedMitsu]

Yes you can

[Medevack1]

i changed it sorry about that!!!!