New Webers - Adj Help Needed

[pope]

Originally Posted by Peter Zimmermann

Early version Webers used idle jet carriers without o-rings, later Webers were fitted with o-rings, which are supplied in all Weber kits. The jets fit both types of carrier.

I presume this means that it's no biggie if I don't put any because, amazingly, my Weber rebuild kit only had 6 o-rings which I used for the mixture screws.

[70SWT]

Yep, this is what I was referring to on Rennlist in post #2 above - sorry I wasn't more helpful with the reference...great write-up, Pete! Wish I had had this when my car still had Webers...

Originally Posted by Peter Zimmermann

I wrote this recently for a project that I'm working on, and posted it on Rennlist. You might find it helpful. Unfortunately I do not have the exploded view with numbered parts to key off of as I did on Rennlist.

Carb balance – please follow the instruction steps in order, there is a certain logic to it all, even though that logic might not be readily obvious!

1. The engine should have new spark plugs, either Bosch (WR5DC) copper core of a comparable NGK (BP7ES), gapped equally to .030”, and the point dwell must be within factory spec, as well as the ignition timing set properly. If your gas ......

[GotaT]

Finally got the carbs to run Really good, but I still think that after the fresh rebuild they should run Perfectly.

I am experiencing some hesitation off Idle and a little popping in the exhaust here and there. My current settings are 1 5/8 turn OUT on mix screws.

Seems that when I turn the Mix screws in slightly I start to hear more Spitting and doesnt seem to have As much power..
Do I need to turn them OUT MORE?

[Peter Zimmermann]

Normally the mixture screws all end up in different positions, and the five 1/2 turns mentioned is only a starting point. The key is to start with all of them at that position, because it ensures that the screws are far enough out that popping from one of them won't skew your adjustment. I made no mention of the final adjustment position of the mixture screws, because that doesn't matter. One screw might end up two 1/2 turns out, another four 1/2 turns out - it doesn't matter. What's important is that all the screws end up past the engine labor point, usually by about one 1/2 turn.

[GotaT]

Originally Posted by Peter Zimmermann

Normally the mixture screws all end up in different positions, and the five 1/2 turns mentioned is only a starting point. The key is to start with all of them at that position, because it ensures that the screws are far enough out that popping from one of them won't skew your adjustment. I made no mention of the final adjustment position of the mixture screws, because that doesn't matter. One screw might end up two 1/2 turns out, another four 1/2 turns out - it doesn't matter. What's important is that all the screws end up past the engine labor point, usually by about one 1/2 turn.

So, if the engine is popping, the Mixture screws need to be turned out, If it spits then they need to be turned in?

If that is true - How can you tell which Mix screw needs adjustment if it is Popping in the exhaust? Or a little hesitant off idle?

[jeffy69911t]

I always thought the 'idle stop screws' or 'idle speed screws' (whatever they're called) are supposed to be screwed all the way out, and are just meant to act as a stop for the throttle shaft.

Because once you start screwing them in, they open the butterflies, thus exposing the first progression hole. In so doing, the carb is no longer running off of the idle circuit. Please advise.

Jeff

[Peter Zimmermann]

Originally Posted by GotaT

So, if the engine is popping, the Mixture screws need to be turned out, If it spits then they need to be turned in?

OK, you have all six idle mixture screws backed out five 1/2 turns - proceed:

8. Starting with cyl #1 idle adjustment screw (your #xx) turn that screw slowly clockwise (maybe an eighth of a turn at a time and then stopping for a moment) until you can hear the engine start to labor (listen at the tailpipe for a slowing of the idle speed).
9. When the engine labors, stop turning the screw, and turn it counter clockwise ½ turn, and immediately move to cyl #2, do the same thing, then on to #3, 4, 5 and 6.
10. Time to get that Unisyn out again and check air draw for all six cyls. Use the cheater screws to make any fine adjustments necessary to equalize air draw. Make sure that you snug down all cheater screw nuts in order to lock the screws.
11. Repeat instruction #8.

[Peter Zimmermann]

Originally Posted by jeffy69911t

I always thought the 'idle stop screws' or 'idle speed screws' (whatever they're called) are supposed to be screwed all the way out, and are just meant to act as a stop for the throttle shaft.

Because once you start screwing them in, they open the butterflies, thus exposing the first progression hole. In so doing, the carb is no longer running off of the idle circuit. Please advise.

Jeff

There are three basic screws: (3 per carb) idle mixture screws, (3 per carb) idle air screws, and (1 per carb) idle speed screw. The first two regulate air intake balance and idle mixture, the third regulates idle speed. The idle speed screws are located on the carb control lever, and they're used to achieve idle speed and side-to-side balance.

[GotaT]

Lets go over some basics.. The condition (rich or lean) , and the Fix (screw Adjustment)

If there is popping in the Exhaust at idle = ? TOO RICH? Turn in Idle Mix Screw?
If there is Spitting on the Intake at idle = ?

Spitting on Deceleration =
Popping on Deceleration =

Spitting on Acceleration =
Popping on Acceleration =

I seem to be currently getting some spitting/minor popping on deceleration and a little spitting if I accelerate slowly and go through the revs. At idle the car runs smooth. Coming right off of idle I have a small amount of surge.

Idle Mix screws all turned out about 1 3/4 or 1 3/4 + 1/8
Vacuum Balance looks Great and all 6 are within a 1/2 on my STE

My #4 idle mix screw doesnt seem to be making much difference, why? and If I turn out the Idle air jet I dont seem to be getting a drop in idle but it is not clogged w/ trash.

[GotaT]

Guys, Yesterday after making all sorts of minor adj I figured out my Biggest problem... There was the smallest piece of metal in one of the Idle Jets! Cleaned it thoroughly and Voila! RUNS GREAT! NO spitting/ poppin, SMOOTH EVERYWHERE..... I just love being able to put it in 5th at 1100 RPM and still be glass smooth...

THANKS for All the posts!

I now wonder whats the best way to getting the most power out of them?

[avendlerdp]

Hey, that's great. Dirt in the idle jets is the #1 reason Webers run poorly. I have seen people chase all kinds of issue$ only to find it was that simple. Check your fuel filter condition. That junk in the idle jets came from someplace.


One last thing. If you are new to setting mixtures use a low speed tach to see the results of your adjustments. As you slowly turn each screw you can see the RPM at idle change slightly. Go over each screw and maximize the RPM. Once done you can lower the idle back down using the stops and get in the road.

[mossguy]

GotaT - Quit while you are ahead, enjoy your car for awhile, THEN go for the 'power' !

Tom

[GotaT]

Thanks again guys... Mossguy.. Absolutely!.. its my daily driver. Hoping to take it on a road trip to Houston next weekend.. Should be fun

Pics to be posted soon of the 3yr Completed drivetrain project!

[pope]

I might as well put it in this thread as it's related. I started my quest to tune my carbs in this thread. I'll continue here.

I have gone through the 'Zimmermann procedure', as I have christened it, 3 times up to now.

I must say that the car is running overall much much better than when I bought it a year ago. My first tuning attempt resulted in a pretty smoothly running engine but with rough idle. The second attempt was worse and the third is the best yet.

Something important: maybe it isn't clear (I missed it in the first two rounds) but it is important that you go back to step #8 after step #10. That is, after you balance the vacuum, adjust the mixture and then go back and balance the vacuum again because it might be off.

During the mixture adjustment procedure this is what happens: I set all mix screws to 5 half turns out. I set idle to 1000 by turning in/out the idle stop screws whilst keeping left right vacuum equal. I start turning in the first mix screw and after a turn or so, the engine starts to pick up rpm's. Of course, when they start dropping again, I stop and turn it back out half a turn (as per the procedure). With each screw, my idle picks up even more, reaching more than 1200 rpm's at the end of the 6th cylinder. I don't know if this is good or bad (it sounds good) but I just thought it was important that I said it.


So, here are the problems I'm having:

Idle
I have a relatively rough idle. When it's cold it needs some gas pedal. When it's warm, it doesn't jump around much but there are traffic lights when it's running at over 1000 and others where it drops to the low 900's (my tach is acting up and jumping around a bit).

Bumper to bumper traffic I think is the worst. After a while I start to get occasional backfiring (at the carbs). With a bit of gas it clears.

Blipping (when I momentarily press the gas pedal a few times) gives the occasional backfire, especially after the heavy traffic.

Transition
Transition from idle or less than 1500 rpm is a bit rough, again especially after the traffic.

Acceleration
In first gear, the car labors noticeably until 5000 (maybe even more) after which it takes off (but there's only 2000rpm left ). 2nd pulls normally although I'm not sure that it's full power - it feels OK. Same with the rest of the gears.

I've been told by a friend that was following that there is black smoke from the exhaust and a gas smell when I accelerate hard. I cannot replicate this in the garage except for a bit of black smoke after long idling.

Deceleration
I think all is well here.




Since I'm guessing that someone is going to ask me this:
Air correction: 180
Emulsion tubes: F26
Idle jets: 55
Main jet: 110

My float bowl levels should be OK after my first gauging attempt but I plan to gauge them again for good measure.

Same with the accelerator pump.




Another issue that I have is that my dwell angle is low at about 32*. I'll be fixing that tomorrow but I doubt (from what I've read) that this is the cause of my problems.

[Peter Zimmermann]

OK, Pope, now we can get serious. But first, (1) what size venturis are you using (look into one of the six carb throats - you'll see a small number cast onto the venturi), and (2) is your engine, including cams and int/ex port size, stock 2.2 liter "E"? Let me know!

[pope]

Sorry forgot to add the venturi size, 30.

I do not know what cams I have, nor the size of the ports. I have no reason to assume that they have been tampered with but this car has had at least 4 PO's that I know of and its history before 1990 is dark.

[911pcars]

There may be other factors, but 110 main jets are fairly lean. 2 liter T engines used 27mm venturis and 110 main jets. You might consider going to larger 125s and see if the symptoms change for the better.

Sherwood

[pope]

Originally Posted by 911pcars

There may be other factors, but 110 main jets are fairly lean. 2 liter T engines used 27mm venturis and 110 main jets. You might consider going to larger 125s and see if the symptoms change for the better.

Sherwood

That's weird because PMO suggests otherwise in #14 here: http://www.pmocarb.com/bulletins.htm

Also, since my lead time for jets is significant, I think it would be best if I put in one order for all the sizes that I should be trying out.

[Peter Zimmermann]

Pope: Given your car's history, do you have a set of jet gauges, or good quality drill bits, that you can use to measure/verify the jets that you have?

If the car were mine I would use the 30mm venturis that you have, 125 mains, 170 airs, and have a set of 50 idle fuel jets on standby. With your symptoms you might find debris somewhere (in an Air Correction jet, or possibly an idle fuel jet), and you might also discover that your "110" mains aren't...

Emulsion tubes are a tough call without knowing what cams your engine has - how hard would it be for you to remove the upper rocker covers, put dial indicators on #1 & #4 intakes and measure timing at overlap?

[pope]

Damn.
I have no gauges or drill bits and I don't know what or how to measure either...

I'm assuming it will be just as time-consuming to get these gauges as getting the other jets themselves. Why would a jet be stamped as being a different size than it actually is

There may be debris in there but it's not likely since I've basically just put the carbs back on after a rebuild. Here's what my main jet looks like just in case it says something to you:

how hard would it be for you to remove the upper rocker covers, put dial indicators on #1 & #4 intakes and measure timing at overlap?

I don't know. I should think you could answer this for me. Is the rocker cover the valve cover? I'll check the books I have if there are any details on how to do this. Any references?