57 replies to this topic

[LC-GTR-1969]

Hi All,

 

I have just finished setting up my new Spanish genuine triple webers on my LC 186 but shes running really rich.

 

I have had them set up by a specialist, and he did get it running lots better by changing the jets, but its still running rich.

 

Are there any experts on these who wouldnt mind giving me some advise.

 

Thanks 

What are the symptoms at the following;

 

1) idle

2) mid range/ mid throttle progression (hesitation? bog? flat spot?)

3) WOT (wide open throttle)

[caterham2]

You obviously have not dealt with a specialist, the world is full of donkeys like this, they have dynos, afr equipment and " expertise", but most of them don't have a clue what is going on unless its a rice burner with EFI. If you were in Australia I could direct you to some real experts.

[EunUCh]

Spanish genuine webers? should have made in Italy on them.

No numbers of what was in them?

how do you know it is running rich?

Not too many people claim to be experts because this only leads to drama,we all know what an expert is,can be a live and learn thing at times.

But those who have played with them can offer suggestions,with no numbers to start with you are basically going nowhere fast.

 

Has been said before when dramas were experienced with previous weber problems...it is not the carbies fault,it is the "specialists" fault.

Although there has been the odd thread around with numbers to start with this is always a good place to start and learn about how they work..they are not rocket science but they are a bit different when you start talking how the main emulsion/main system works.

 

 

 

[jd lj]

Hi thanks for all the feedback!

 

I will get to answering all these.

 

Big hesitation and initial throttle, then it goes pretty good, if you let the gas off and ease it back on.

 

Yes, 45s Jetting is -

 

choke 36                                                         (all good)

main 145                                                         (should be ok)

Avconjet? "Cant read hand writing" 185    (this would be the air corrector jet, 185 should be close but could go up a size or 2)

Talse "cant read hand writing" F16            (this would be the emulsion tube, most of us use F2's , but F16 is the next closest)

Pump Jet 45                                                   (may be a size or 2 too big???? is there much smoke at "WOT")

Pump Bleed 40                                              (linked to the above)

Idle Jet 60F9                                                   (most likely too big for a 186, I,m using 50f8's on my 202, so I assume a 186 would be smaller, maybe 45F12)

What size auxillary ventrui are you using, 45 or 50?

NOTE: the above information is a guide only, testing is required to confirm what's correct for your particular engine, each one will be different. Don't worry there's only 13 billion 600 million or so combinations to choose from on DCOE's.

[jd lj]

Unfortunately it's just a process of trial and error and testing with a air /fuel meter to get the correct ratio.
Read as much as you can about them and learn what each jet is responsible for.

[LC-GTR-1969]

Hi thanks for all the feedback!
 
I will get to answering all these.
 
Big hesitation and initial throttle, then it goes pretty good, if you let the gas off and ease it back on.
 
Yes, 45s Jetting is -
 
choke 36
main 145
Avconjet? "Cant read hand writing" 185 
Talse "cant read hand writing" F16
Pump Jet 45
Pump Bleed 40
Idle Jet 60F9

 
Just a few comments...
 
Hesitation on initial throttle does not necessarily signify the engine is running rich... could be, but it could also be other issues. Ones perception of what a hesitation is is different to anothers, which makes internet diagnosis difficult...
 
I have had work done by apparent weber specialists, only to have the carbs returned out of synchronisation and the linkages set up incorrectly (idle set by adjusting the linkages, a big no no).
 
1) does the car idle? If so, what is it idling at?
2) When you say 'hesitation', is that a 'stutter' (in other words does the car nose dive)? or is it basically where the engine needs to kinda 'catch up to itself)?
3) Do you have access to a synchrometer? This is the one I would recommend...http://www.weberperf...3&products_id=7 This tool will check whether the carbs are synchronised properly. Dont presume they are- the mechanic could have balanced them, then installed the carbs, and may have incorrecty installed the linkages which will throw the balance off.
4) What are the carb idle mixture settings? If you tighten these in slowly, counting how many turns until the screw just seats, then record the setting for each THROAT of the carb. If the idle jet and air bleed are close to correct, each runner of the carb should be between about 3/4 turn out and 1 3/4 turns out. This will help you work out whether your idle jet is correct.
 
Work out the above three first to establish a baseline. 
 
A few comments on the 'jetting'... I havent noticed any major issues, but a few observations...
 
-the choke size should be fine... 36-38 can be used successfully on a street driven car...
- The emulsion tubes for red 186/202s are often F2 but F16 may also work...(I think this is where you have deciphered this'Talse "cant read hand writing" F16')  w from the mechanics notes
- The main jet is in the ballpark (each engine is different)
- Where you refer to 'Avconjet? "Cant read hand writing" 185 '- This will be referring to your 'air correctors' 
 
This table may help;
 
 Screen Shot 2014-12-09 at 6.26.19 pm.png   37.63K   16 downloads

Edited by LC-GTR-1969, 09 December 2014 - 06:11 PM.

[EunUCh]

As ^ F2 emulsion tube might be one place to start?

They are a bit "richer" than an F16.

Never really understood why they have so many variants on those things,but there must be a reason.

First  thing is get them in synch.

Then get it to idle nice,not sure on triples on 9 port but on IR the idle mixture screw should make a difference within a half turn at approx.

11/4 to 11/2 turns out from seated.

Then you can work on transition (very light openings/low load),this is run by idle jet as well.

Then mains,they do pull over quite early and a seat of pants way is to see if it gets "soggy" when warm as to compared to a cold start when driven.

The high speed air bleed is another story,it will only start working once (from my view only) the main well is empty and the fuel is being ripped 

out so fast the well barely has time to fill.

Then the other problem,they reckon that even the pump nozzle will pull over to richen things up a bit as well at high rpm.

[jd lj]

^ yes the weber factory tuning manual says that the pump jets will also add fuel to the mixture at high engine speeds.

The fuel level in the float bowl will also affect the main circuit and should be 25mm down from the ledge where the emulsion tubes screw in, this can be measured with the engine idling and the emulsion tube assembly removed (they don't do anything until around 2500 -3000 rpm).

The jetting guide above supplied by weberperformance carburetors is a good start.

The first things you need to do are ensure you have no air leaks in the induction system, set the idle mixture screws as per the "best lean idle procedure " google that one. Next synchronise the carbs at idle and at 2500 rpm. Now trial different idle jets until you find one that works for you. Don't worry about the main circuit until the idle and progression circuit are sorted.

[Bigfella237]

Another thing not mentioned so far is that having nice even compression figures across all cylinders is a lot more important than with a single open plenum setup too, having one lower than the rest can make tuning difficult but you should be okay with this being a new engine.

 

I find the easiest way to set idle mixtures is by ear, listening to each throat through a length of tube while adjusting you can hear the sweet spot for each, but it takes a little practice to know what it sounds like.

[jd lj]

Bogging down at sudden WOT can also be due to being too lean.

My car had this problem when it had 40mm chokes fitted and I accelerated rapidly while still on the idle /progression circuit. This wasn't a problem at higher rpm's though as there was enough air speed to be running of the main jets.

The problem is that the butterflies open suddenly and allow maximum air flow, the pump jets are meant to compensate for this in theory.

Well enough of me rambling on and back to your car.

Going by the jetting specs you gave us last week I would be surprised if your car was too rich considering it's a 186 and not a 202.
When you experience this problem is there much smoke coming from the exhaust and what rpm's is it occurring at.

[jd lj]

Just need to edit my last post :

It should read that I WOULDN'T be surprised if your car was running rich (my phone used "would" when I wanted "wouldn't").

[EunUCh]

What have you changed since the last "tune up"?

Best to pull the cover off the the carbs and pull the tubes out and see what numbers are actually on each part?

3 wing nuts to undo and a good fitting screw driver/s and you will have them out in under 5 minutes.

Just because ol mate wrote down some numbers it pays to confirm,and even then, people that have numbered drill sets can bore things out while leaving the original number on the jet/s/bleeds etc.

 

sort of sounds lean, but if it was that bad you might expect a backfire, if it was that bad?

bloody hard to describe rich/lean conditions in words!

sounds like the mains are not pulling over early enough,hence the slight rant on emulsion tubes,they have different size "barrels" and the number/postion/size of holes all play a part in when this happens,being 2 chokes per cylinder kills air speed at sudden WOT openings.

Not enough signal at low engine rpm needs the mains to pull over early.

 

I would suggest fit some F2 and leave the rest and try that.

Edited by EunUCh, 18 December 2014 - 06:23 PM.

[jd lj]

Only change one thing at a time, then test for the results. If you do multiple changes it's hard to keep track of what results your getting from what.

Does it ever back fire and if so is that out of the exhaust or the carbs?

Drive down the steepest hill you can with no throttle in 1st or 2nd gear (ie under compression) and listen to see if it pops at the exhaust. If it does the idle is lean. That's a nice and easy test with no equipment needed. But it only will test the idle not the mains etc.

[EunUCh]

^ 

[EunUCh]

Well! that certainly blows the base lines out of the water doesn't it?..although a 145 main is only .05mm smaller than 150..not much at all but it will make a difference..just not enough ?

 

might be just a matter of downsizing the mains a bit and see how you go?....i would try 135.

cheaper than tubes.

As has been said before,make sure they are in synch and float levels set first...they are new and levels "should' be 'ok' but never can tell theses days.

 

 

[LC-GTR-1969]

Update, not back firing down hill in low gear. But it does backfire occasionally, out of the carbs, when taking off from the lights. So at initial throttle.

Backfire through carbs can be from running lean, but this would likely also pop on decel through exhaust... However carby backfiring with triple webers is usually caused by unbalanced carbs... when mine starts spitting through the carbs, its a tell tale sign of incorrect synchronisation. As said, the carbs may have been balanced correctly, but he could have thrown out the balance when installing the linkages (common and easy mistake).

Edited by LC-GTR-1969, 20 December 2014 - 06:39 PM.