Ida idle dripping

[1950split]

I noticed that although my float level is set properly I have the accelerator pumps dripping.

I made a quick test and by moving away the accelerator pump rod from the lobe on the shaft, dripping completely disappears.

I noticed that even with idle speed screws fully turned out, the accelerator pump rod is always in contact with the ramp on the throttle shaft. Is this correct?

Can I slightly grind the ramp off in order to eliminate contact at idle and fix the dripping this way ?

Carbs are brand new Spanish idas. 42 vents, 60 idle, 120 idle speed, 170 main, 200 air corrector and F2 emulsion tubes, 300 Weber needles and 3psi fuel pressure.

Engine : 82x94, 86c cam, 44x38 mid D brothers heads.

Thanks for your help

Phil

[Ohio Tom (DdK)]

Hmmm. That's odd.
I know that when the throttle shafts wear out the bores in the carb bodies, it can cause this problem.
Usually means the death of the carb body or a trip to Art to get them re-bushed.
Howerver.... on a new carb, that shouldn't be happening.
Grab the shaft where the cam is attached and wiggle it around. See if it moves up/down. Anything visible to the naked eye is too much.
Should only be a few thousants of an inch play.

There are ways to band aid the problem, but find out what it is first...

[Bruce Tweddle]

I noticed that even with idle speed screws fully turned out, the accelerator pump rod is always in contact with the ramp on the throttle shaft. Is this correct?

That is correct.

The theory I was told was that the pulses of the engine cause a small amount of fluttering of the throttle shaft.  This movement causes a small movement of the pump rod.

One cure was to advance your idle timing.  This will cause the idle speed to increase, allowing you to close the throttles more to get the roller off the ramp of the pump cam.

At one time Bergs sold a bolt-on pump cam that was infinitely adjustable so you could set it where ever you wanted, at whatever idle speed and timing you wanted.  I don't know if they still sell them.

[1950split]

Thanks for your answers.

I tried to set up the carbs again last night, unsuccesfully.

I checked the play of the shaft but there's no play so I guess that on this side the carbs are fine.

I advanced idle timing to 10°-11° before TDC and then readjusted the idle speed screws and idle mixture screws but it didn't change anything on the carb. The carbs are still driping from the squirters.  

What I noticed as well is that cylinder 3 and 4 show different values on the sync and the difference is quite important about 1.5.-2 units less. Maybe I have a bent shat on that carb but they are new?!?.

One thing I'd like to know. The lever has a return spring in order to push it against the ramp on the shaft. Won't it be useless to grind the ramp as what I would grind of would be compensated with the return sring pushing the lever on the ramp !? Or is there a point after which the lever cannot return more against the ramp ?

[NoBars]

Fuel pressure?

[Ohio Tom (DdK)]

Yeah, I don't think you should be looking at grinding or modifying your pump cam.
I'm with Nobars on this one. Either your fuel pressure is too high or your floats are not set correctly.
They are very sensitive on IDA carbs. 0.5mm off and it will drip like you describe.
Try this: While the engine is running (and you see dripping), turn off the fuel pump and let the motor run. If the dribbling stops after 30sec of running, then fuel inlet control is definatly the problem..

[1950split]

hi,

Fuel pressure is set at 3.5 psi with the engine running.

Float level is set at 5,5 precisely and the tab for the needle s at 24mm with the float at 5,5.

If float level was set incorrectly wouldn't fuel pour out of the progression holes?

[Ohio Tom (DdK)]

No, it will dribble out around the pump squiters.
24mm should work fine.
Are you sure it's 3.5psi? Calibrated gage?
Most are off by a PSI or 2.

Is there are fuel pressure where it doesn't dribble?

[maui]

take off your linkage and put some strong return springs and adjust carbs again and see. If you tried everything else so this won't hurt.

[1950split]

The regulator is a holley 1-4psi with an 15psi Automotive gauge. It worked well with my other engine that has 45 DRLAs.

I will try to reduce psi amount to around 2 psi for test. Someone suggested me to set the float at 5,5mm and the tab for the the needle should press the "ball" in by 2mm at this level instead of just making contact with the needle. What do you think of this?

[Ohio Tom (DdK)]

Are they glass ball inlet valves?

[1950split]

No, needles are 3.00 Weber I got from GB.I chose this option over glass balls as I had read about quality issues..

[NoBars]

Turn the pressure down and see if it goes away. I had this issue with the 3.0s and run a hair under 3.5 psi

[Bruce Tweddle]

2.5 inlet valves will control the fuel level more precisely.  Give them a try.  Maybe even 2.0s.

[1950split]

So, tonight I checked valve gap on the 4 cylinders and it is loose zero with the chromo pushrods.

I reduced fuel pressure to 2 psi, no change.

I rechecked float level which was really at 5.5 and needle at 24mm. I reduced needle to 22 so that the needle is surely closed. No change either.

I must mention that it is really on 3&4 side that fuel is pouring out of the squirters and mainly out of #3.

I noticed again this variation of vacuum between 3&4 of 1 unit although while the carb was off the car I checked for a warped shaft but it is ok, butterflies open the same amount. I checked it with a feeler gauge.

I'm womdering if a vacuum leak between manifold and head could cause this type of problems? What do you guys think of my idea?

[deano]

This may or maynot play into this problem, but while you are looking closely at this particular IDA, make sure both butterflies are open exactly the same amount. Use a feeler gauge to check... Bent shafts are common...

[Jason Foster]

  I was set to suggest a possible bent shaft as well as I agree with Dean, I did read that you say you've checked for that in your last post.  An intake leak is a definate possibility for the difference in vacuum readings i agree with you there you'd be having other noticible tuning issues though but deffinately check it out.  I suggest taking a second look at the possibility your shaft is bent.

[NoBars]

HuuHHHuuuhhh bent shaft...

[mmccarthy]

 We had the same problem years ago, thought it may have been a check ball not seating properly .

[1950split]

Ok, I switched the carbs. The one that was dripping a lot on the 3&4 side is also dripping on the 1&2 side now. The positive thing is that both throats show the same amount of depression with the sync tool. Therefore I shouldn't have a bent shaft. Both carbs have the float level adjusted the same way. Maybe a bad needle ?!? I'm not left with many options..

What I noticed is that, after the switch of carbs, I have no response from the idle mixture screw on throat #3 and a value of about 5-6 with the sync tool compared to 7 on the other throats. When I spray carb cleaner in the venturies of 3 the idling is nearly not affected and a hand covering the venturi does not affect idling either.
I then sprayed carb cleaner around manifold base and at junction between carb and manifold, no reaction. Could it be that I have a leak on valves?

[1950split]

Hi Guys,

Please tell me what you think about my idea of the source of my problem.

My carbs have had the 3rd progression hole drilled.

What I noticed tonight, when synching my carbs and adjusting idle mixture screws is that when on that carb, my uni-sync shows a value above 6, which actually relates to 950+ rpm, my squirters start dripping. As long as I stay just below 6 and 950 rpm at idle there's no dripping.

Do you think that 3rd progression holes drilled a bit to close to the butterfly could cause this leaking when the butterfly is open to much ?

I finally did my idle mixture adjustements at about 850 rpm.

I'm a bit anxious to leave my idle speed at this low range as I'm using CB650 springs which are quite heavy and I was told that with this type of springs it is better to idle at 1200-1400 rpm.

What do you think ?

Actually I'd be curious to see what would happen if I shut the 3rd progression holes and give it a try but I don't know what I could use to close it definitely

[NoBars]

try swapping inlet valves between carbs and and see if the problem moves with it

[Bruce Tweddle]

As long as I stay just below 6 and 950 rpm at idle there's no dripping.
I finally did my idle mixture adjustements at about 850 rpm. 

That's what I told you to do 2 weeks ago, reduce your idle speed.

I'm a bit anxious to leave my idle speed at this low range as I'm using CB650 springs which are quite heavy and I was told that with this type of springs it is better to idle at 1200-1400 rpm.

What kind of testing did they do to require this?  How long do you let your engine idle for?

[1950split]

NoBars, I tried with another needle, 200 but same problem.

Bruce, it is still weird that this dripping occurs only on one carb, the other, even at 1200rpm does not drip.

I'll have to find out the recommended idle speed with these springs. Maybe Tom (Ohio Tom) will chime in and give us his opinion. He used these springs several times.

[1960 ragtop]

OK this is the same issue I fought for several weeks and sending carbs back in for repair. What I found and have heard of a few others is that the ramp on the cam is in contact to much at the idle position. I took a dremel and a sanding drum and re-profiled the cam so that there was just a tiny air gap there at idle position. Carbs are fine and sync perfectly. been running them for 6 yrs now no problems. Use a sanding disc and only remove what is needed to stop the drip.

[Bruce Tweddle]

Take your distributor out and look at the advance mechanism.  Modify it to reduce the amount of advance.  Then install it and time it to the same amount at full advance that you had before.  At idle, the timing will now be more advanced.  At your current throttle plate position, your idle speed will be higher.