48 IDA idling problem

[Stefan Rossi]

Hi

So my ida's stilll leak at idle, so iv backed them off totaly to avoid cylinder wash and now hav to feather my accelerator at traffic lights sounding like a dick 

after reading loads on here and other sites, i hav tried to file down my accelerator pump rods. this has not stopped the fuel leaking at idle.. do i file more or will this cause problems?

iv heard people hav made sleeves to go over the rod, but i cant figgure out where the sleeve should be placed? on the rod at the bottom by the accel cam?

i want to sort the problem tomoro as i hav the time to do it and drivin the car daily like this is starting to piss me off 

thanks

stef

[dannyboy]

efi m8 
see you on the 31st m8

[Stefan Rossi]

boring 

yeah mate, cant wait,

fixed my rev counter and my msd works a treat

cant wait for the 31st, its running mint apart from the idling problem! dont think iv seen a pic of your new car!? wats going on 

[Diederick/DVK]

can't help you with the issue.
but i gather the wiring scheme worked out? i could use that info to wire up my brother's engine in the future.
good luck though!

[Stefan Rossi]

yes it worked awesome thankyou!
made it real easy to install, i actually enjoyed it! 

[Bruce]

Advance your timing.

[Bernard Newbury]

Hi

So my ida's stilll leak at idle, so iv backed them off totaly to avoid cylinder wash and now hav to feather my accelerator at traffic lights sounding like a dick 

after reading loads on here and other sites, i hav tried to file down my accelerator pump rods. this has not stopped the fuel leaking at idle.. do i file more or will this cause problems?

iv heard people hav made sleeves to go over the rod, but i cant figgure out where the sleeve should be placed? on the rod at the bottom by the accel cam?

i want to sort the problem tomoro as i hav the time to do it and drivin the car daily like this is starting to piss me off 

thanks

stef

Have you checked your needle valves and float levels?  Fuel pressure?

[Rasser]

Checked your valves and seats lately?

I thought mine were perfect because I had a machine shop do the work when I build my engine. But I had the same problems with the acc. pump squirting gas at idle (just on cylinder3-4).
I took the heads of and lapped the valves. Did a check to see if I got a good "grind pattern" in the seat - I did! 
I then filled the chambers with liquid, and then I could see that one of the valves/seats were leaking a little bit - just a little bit!
I then borrowed a valveseat toolkit, and redid that seat the way it should have been done from the beginning!

I have not had the problem since that, so I am 100% sure that the problem was caused by a leaky valve/seat.
The IDA carb is extremely sensitive to this because of the way the acc. system works.
If the "combustion" blows up the intake, then the throttle will pump slightly with the pulses from the engine.

I could NOT measure the leak doing a compression test.

Hope this helps others with similar problems.

[Stefan Rossi]

hi

fuel pressure and needle valves are fine, its defonaty from the engine pulsations because when i took the cam off it doesnt leak.

i now hav it idling ok but the carbs still leak

where is the sleeve some people iv heard of fitting ment to go to stop it?

does lenghting or shortening the accel pump rod make any difference?

if non of the above work im going to take the cam off and grind a bit of a flat spot on it

thanks for all your help so far.

stef

[carlnolen]

So, is this the problem you are having? There is a fuel drip from one or more accelerator pump nozzles into the carb bore at idle??

Carl

[Bruce]

if non of the above work im going to take the cam off and grind a bit of a flat spot on it...

Advance your timing.

[Jason Foster]

  make sure throttle shaft is not bent. closing one butterfly early while the other still slightly open and on cam

[Carsten]

Maybe throttle shaft is loose in the carb housing! Engine vibrations make the throttle shaft vibrate , too.
That causes the accelerator pump will always be hit a little bit and starts to drip !
Had that problem on one set of my IDA carbs . Try to hold or push against the throttle shaft in the area where the accelerator pump sits. If it stops dripping , you have found the problem ;-)
Greets , Carsten

[Stefan Rossi]

Yes this is the problem, pretty much from all pump jets

Stef

[Carsten]

Yes this is the problem, pretty much from all pump jets

Stef

So , housing is worn or , but i dont think so , the throttle shaft . Old problem of old IDA`s.
Drove mine like that for years ;-) My MSD solved the problem by burning all the unused fuel !!!
The only way is to rebuild the carb housings :-(
The outer side is no problem , there are bearings ,put new ones in !
But in the inner side there is nothing but the housings cast aluminium. The only way would be to drill it to a bigger diameter and put bronce bushings in with the right diameter.
No easy thing to get the carb housing "line bored"through the side were the bearing is. You should use new throttle shafts , too.
Maybe someone has a better easier idea ?
Have you got old italien ones ?
Greets , Carsten

[Stefan Rossi]

Hi carsten, I'm not sure if they are worn tho? Iv had it all apart and it doesn't look worn.
I'm sure that it is the impulses from the engine intake strokes because when I hold the cam still it doesn't leak.
But when I let go and it flutters and leaks, it only needs to move 1mm or 2 before it starts dripping.
How can I cushion this so the flutterations do not aftect the pump jets.

Bruce, surley if I advance my timing to say 10 my full advance will be too high and cause to much damage?

Its set at 32 degrees full advance at the moment.
009 dizzy with petronix and msd 6al is the igniton system I'm using.

Its running good now, abit rich and stinks but rich is better than lean and it runs like a bag of shit with the fk89 if not rich

I have found my jets now so that will be getting sorted, but even so this leak at idle is still there :s

Thanks

Stef

[Bruce]

Bruce, surley if I advance my timing to say 10 my full advance will be too high and cause to much damage?

Its set at 32 degrees full advance at the moment.
009 dizzy with petronix and msd 6al is the igniton system I'm using.

Will your engine tolearate more?
Figure out how to modify the distributor so it advances less.  Then set your total to 32º.  This will advance your idle timing.  This causes your idle speed to increase.  This causes you to close the throttle plates more.  This causes the IDA's accelerator cam to pull away from the roller on the lever.  This fixes your problem.

[Rasser]

Bruce, surley if I advance my timing to say 10 my full advance will be too high and cause to much damage?

Its set at 32 degrees full advance at the moment.
009 dizzy with petronix and msd 6al is the igniton system I'm using.

Will your engine tolearate more?
Figure out how to modify the distributor so it advances less.  Then set your total to 32º.  This will advance your idle timing.  This causes your idle speed to increase.  This causes you to close the throttle plates more.  This causes the IDA's accelerator cam to pull away from the roller on the lever.  This fixes your problem.

Mine is "on" cam all the time! also when throttle plates are backed all the way up.
I understand what you are trying to acheive with advancing the timing+backing up the throttle, but maybe it doesn´t help on the new IDA models out there (spanish)?  not on mine anyway (I tried to do what you are explaining, when I had the problem with acc. pump jets dripping).

When it´s "on the cam" all the time, then the only proper fix is to fix the cause of the problem - and I believe it is leaky valves/seats. Or maybe just the cam/engine combo?!

[Taylor]

What does it sound like or do at idle?  I had a rough idle before due to a leaky needle and seat,  :)cleaned them and it went away.   You said you checked that though.  Here is an idea not mentioned yet I recently had exactly the problem you described, when I took the Carbs off I noticed the butterflies on one Carb were slightly off in relationship to the body/bore causing the progression holes to be exposed. It acted like a bent throttle shaft and the return spring tried to close it all the way causing a sort of pulsation like you described.

[carlnolen]

Yes this is the problem, pretty much from all pump jets

Stef

I have actually had this conditon on two sets of IDA's over the years. While the motor is idling, fuel drips slowly from one or more pump nozzles. As this conditon is currently happening, you can simply reach down and push the cam away from the pump rod and dripping stops. What I found was excessive movement of the cam housing on the pivot rod that's part of the carb. Tighten up the shaft ID on the cam, problem went away.

Carl

[Jon]

What I found was excessive movement of the cam housing on the pivot rod that's part of the carb. Tighten up the shaft ID on the cam, problem went away.

I didn't get it Can you explain again for us that are a little thick?

[H67bug]

There seem to be threads about this regularly.  Not sure if it is helpful but the link below might make identifying parts easier...

Just to clarify, can you let us know if they are new (Spanish) or old (Italian)?

When you look at the bottom of the carb there is a round bush on the spindle that goes through the carb (No 29) . Is that round bush worn with a groove in it? Does the cam lobe ( No 36) that touches that bush touch all the time and if you back it off a little does the leaking stop?

On my old Italian ones the bush was worn, on my new ones the cam lobe needed to loose a fraction. A club member with new carbs had float bowls ( No 15) that had a pin holein causing the carb to over fuel and bore wash the cylinders.

Not sure there apppears to be a "silver bullet"- just a long list of fault finding.

H


http://www.carburetion.com/diags/48IDAdiaginfo.asp

[Jesse/DVK]

Kicking this topic back up. I have the same problem on my new engine on the 1&2 cil side. I want to fix it before I go to the dyno. I already have increased my idle advance and when i complety close the throttle it still leaks.

Could Carl explain his little trick maybe?

[folkevogn]

I had the same issues, my solution the problem was to make a sleeve and slide it over the rod underneat the floater chamber(where it hits the cam). I made the sleeve a little bit longer(around 1mm) than the part of the rod sticking out underneat the carb. This makes the cam rest against the sleeve instead of the rod at idle. No leaks and the engine running smooth all the way from idle(the "delay" is not noticeble at all).

Regards

Folke Vogn

[Jim Ratto]

I don't think I would grind a flat into the roller. You'll have a throttle pedal which is close to imossible to open.
Are you 100% sure your float levels and needle valve heights are exact as Weber prescribes?

good luck,

Jim Ratto

[Jesse/DVK]

I'm almost sure they are ok but will check them again this week. Any other options?

[Sarge]

...."I don't think I would grind a flat into the roller. You'll have a throttle pedal which is close to impossible to open."

Truer words were NEVER spoken!

[Jesse/DVK]

Just one other question. I also want to try a different size idle jet holder. Any ideas which size gets me in the ballpark? Engine size is 2176cc with 37mm vents (maybe going to 40mm) webcam 86c, Steve tims heads, 10:7-1 CR.