Weber Set-Up and Tune Discussion - Page 27 - JeepForum.com

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post #391 of 1100 Old 04-08-2012, 10:44 PM
TrebleHook
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32/26 and DUI distributor

Fellas -

I have read and re-read this thread and many others...GREAT STUFF. Hoping to hear some thought on my particular situation.

OLD: (My 258!) MC2100/China HEI clone.

NEW: 32/36 Kit/DUI distributor.

The 32/36 was installed my a local mechanic - long story. He did some interesting fab work on the linkage in the kit apparently because I did not have the stock throttle set-up with the old MC2100. I tried to snap a few pics (below). From what I can tell the linkage works fine - but looks odd.

I installed a new DUI street/strip distributor curved with 24* at 3000 rpms - from the factory. Had it on "s" port vacuum advance (VA) and it was knocking like MAD at PTC. With the vacuum advance disconnected/plugged - no knock, but not really "peppy." Too much timing was being pulled in creating a lean condition at PTC with my tires/gears/load (as I understand it). Had some issued with the LiveWires fitting. Used a couple of my old wires on #3 and #4. I'll fix this eventually - but it seems to be ok, just ugly.

Switched over to manifold vacuum this morning. The result (as I understand it) is that the initial timing now "includes" part of the vacuum advance that is available from the DUI. The timing is set at 10* BTDC. No knock at PTC that I can notice. Perhaps some knock around 3000 rpm -- I am considering backing down the initial a touch but don't want to loose performance from my new DUI.

At the same time this morning - I attempted to tune the 32/26 according to this thread and others. Backed off the speed screw until it wasn't touching. Backed out the mixture screw 2.5-3 turns. Got it started by fingering the throttle linkage. Turned in the speed screw about 1.5-2 turns....and then back out...I was really was just listening until I couldn't hear air/fuel being sucked through the main circuit -- to get the throttle plate closed (as I understand it). It was BARELY idling. Tach read 400 rpms.

Turned the mixture screw (1/4 turns) in until the idle improved and then started to die. Turned it out about a 1/4 turn. It's idling at 500 rpms.

It seems to run pretty darn well but it STINKS rich - I think. I just know it stinks. The exhaust is putrid and strong - but not wet that I can tell. It was wet with my MC2100 and old HEI. I do have some blow-by and I know it burns some oil, but it's never smelled like this.

My main concern is that I have not fixed the timing/knocking...just covered it up with more fuel?

I have to say that I was doing a lot of "JeepHammer" reading and I realize that he has a different opinion on this issue. He claims the real solution is to limit the vacuum advance with a limiter kit. Problem is, I have a hard time believing that all the guys running DUI/Weber 32/36s with 33s and 3.73 gears have had to go that route. Especially since manifold vacuum (as I understand it) would limit the total vacuum advance under load since it's required to be taken into consideration when setting the initial timing.

I am going to try to re-tune the carb again tomorrow - but would appreciate your thoughts...

Cheers,
TrebleHook

Sorry the pics suck. I rigged on an air cleaner to get cooler air. It's not right but I didn't remove it before snapping these on my phone.

You'll see a little piece of red tape over then end of the choke-thingy. There is a vacuum leak there -- I think that it's missing a screw? Or is that supposed to suck air. It doesn't appear to effect performance, but I am probably wrong on that.

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1983 CJ8 Scrambler Laredo - 258 MOPAR MPFI/T-5/Dana 300 - 4.10 Dana 44 Rear/Dana 30 Front w/ ARB lockers front/rear - 4" BDS Suspension w/ Fox 2.0 Shocks - Ground Pounder Fab Front Shorty and Rear Spare Custom Bumpers - PSC Steering w/ Borgeson Shaft - 33x10.50 BFG KM2 on 15x8 Mickey Thompson Classic III - Work in progress.....
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post #392 of 1100 Old 04-08-2012, 11:28 PM
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Yes, there should be a screw in there to adjust the choke pulloff (I think that's what it is) its a little diaphragm that can be adjusted, sometimes there is a brass plug blocking access to the screw, but clearly your missing both. Swatson454 would be able to tell you exactly, or some of the other guys here on here.

Could be the reason your running so rich.
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post #393 of 1100 Old 04-09-2012, 03:33 AM
John Strenk
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I'm not even going to ask how you flattened one side of the rare tachometer. I didn't know they even made them to only 4000 RPM.

I see you still have the EGR valve hooked attached? Is it hooked up? If not, then maybe hooking it up will reduce the pinging and alow you to keep your current vacuum advance.


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post #394 of 1100 Old 04-09-2012, 04:30 AM
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Treble,

Welcome to the world of manifold vacuum. I think you will enjoy the low end performance improvement and the better cold starts it allows. You shouldn't be getting much, if any, vacuum advance at 3K under load with manifold vacuum. Once you back off the skinny pedal, vacuum increases, then manifold will add advance as it's suppose too. I recurved my Motorcraft dizzy to give almost 20* of mechanical only (not including initial), and over 50* (initial+mech+vacuum) above 3K RPM. But that's sitting in the garage under no load. My engine never sees that much advance in load situations with manifold vacuum.

Yes, that's an interesting throttle linkage your mechanic rigged up. But, hey, if it works....

It's always possible your timing chain may be off a few degrees, and not giving you an accurate reading. I think Shawn has a procedure for checking that. If I recall, his was off a few degrees as well. Try backing it down to 8* and see what happens.

There should be no air "leaking" from the 32/36, when hooked up properly. If you can feel suction at a unplugged orifice while the engine is running, either something isn't plumbed right, or it needs to be plugged. The leak is most likely causing your stinky exhaust condition.

I think I gave you my vacuum layout for the 32/36 with manifold vac to the advance, didn't I? If not, let me know, and I will post it again.

Good luck,

Matt


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post #395 of 1100 Old 04-09-2012, 08:08 AM Thread Starter
swatson454
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Treblehook,

If I'm reading it correctly, you have your timing at 10* while on manifold vacuum, meaning you backed it down to 10* after hooking up the vacuum advance? Did I read that wrong?

You have a vacuum leak and a missing screw there at the pull-off diaphragm? What in the world happened there? Who dunnit?

This isn't really a helpful post, I know, but we need to make sure we're square on your timing set-up before we go all over the place with other stuff.

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post #396 of 1100 Old 04-09-2012, 08:16 AM
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Quote:
Originally Posted by swatson454 View Post
Treblehook,

If I'm reading it correctly, you have your timing at 10* while on manifold vacuum, meaning you backed it down to 10* after hooking up the vacuum advance? Did I read that wrong?
Good catch, buddy.

I was assuming Treble knows to unhook and plug the vac advance when setting the timing, but perhaps not.

I guess we'll wait and see.

Matt


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post #397 of 1100 Old 04-09-2012, 08:50 AM
TrebleHook
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Quote:
Originally Posted by swatson454 View Post
If I'm reading it correctly, you have your timing at 10* while on manifold vacuum, meaning you backed it down to 10* after hooking up the vacuum advance? Did I read that wrong?
Correct. It's at 10* with the manifold vacuum hooked to the distributor.

I'm going to swing by OAJ (my local Jeep guys -- NOT the ones who installed the carb, or it would have been done right!) and see if they have a screw I can steal off an old Weber.

I'll give DUI a call...I'm actually more irked about the LiveWires than the timing.

Thanks for the help. I'll update when I've worked it a bit....

Cheers,
TrebleHook

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post #398 of 1100 Old 04-09-2012, 08:52 AM
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Treble,

Not to steal Shawn's thunder, but you should set the timing with the vac advance disconnected and plugged.

Right now your initial timing is severely retarded.

Matt


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post #399 of 1100 Old 04-09-2012, 08:53 AM
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It's going to run much better with setting it at 10* WITHOUT manifold vacuum. Then don't touch it again after you re-connect the manifold vacuum.


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post #400 of 1100 Old 04-09-2012, 09:02 AM
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Quote:
Originally Posted by John Strenk View Post
It's going to run much better with setting it at 10* WITHOUT manifold vacuum. Then don't touch it again after you re-connect the manifold vacuum.
John,

I can't wait for Treble's reaction when he gets his timing in the ballpark. It's going to run like a different engine.

No wonder his exhaust stinks....

Matt


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post #401 of 1100 Old 04-09-2012, 09:08 AM
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Exactly, I did this myself once and the difference is amazing!
You would think you hooked up a 50 HP NO2 shot somehow.

And gain 5 mpg also.


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post #402 of 1100 Old 04-09-2012, 09:12 AM
TrebleHook
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Quote:
Originally Posted by Matt1981CJ7 View Post
Good catch, buddy.

I was assuming Treble knows to unhook and plug the vac advance when setting the timing, but perhaps not.
Ummm.....don't presume anything....I am having a little DOH! and AHAH! moment at the same time....

I think I misunderstood manifold vacuum. I had the manifold vacuum hooked up while setting the initial timing -- so that I had to retard the timing to include the manifold vacuum (approx 20Hg @ idle) and then set it at 10*.

Thus, my timing is WAY retarded at idle and therefore probably why it's pig rich. This would also explain why I can't get the carb to tune. Am I on to something?

On the other hand, fixing this - so that I have the extra manifold vacuum at idle but not under load - won't fix the knocking will it? I'll still be pulling in the extra vacuum at PTC, right?

Back to the drawing board....

Cheers,
TrebleHook

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post #403 of 1100 Old 04-09-2012, 09:17 AM
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Treble,

Sorry for assuming, some of this stuff gets second nature after you've tinkered with tuning as much as some of us have.

The retarded timing, and vacuum leak, are definitely the root of all your troubles right now. Fix those, and the carb tuning should be a breeze. Start with the leak. Doing anything before you fix that will be a waste of time.

Matt


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post #404 of 1100 Old 04-09-2012, 09:40 AM Thread Starter
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Hopefully uptillnow will chime in with some advice regarding that missing screw.

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post #405 of 1100 Old 04-09-2012, 09:48 AM
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Hopefully uptillnow will chime in with some advice regarding that missing screw.
If not, or if it takes a while for UTN to respond, I'd be willing to take the one out of my 32/36 and send it to Treble. I can always replace it later.

Treble, let me know....

Matt


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