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Idle speed adjustment screw for Twin Webers


mtriple

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Thanks to all that helped with my previous issue (not able to get past 4.5k or 90mph) The issue was the linkage. Now that is (almost completely done) and I can get to 110mph no problem.

How do I drop my idle speed? It seems that its at 1400 and I would like to drop it to the 900/1k spot. If I use the same theory when I adjusted the idle on my SB Solex, then the screw I circled below should be the correct one to adjust idle speed.

I have the IE Linkage with center pull.

Is this the right screw to adjust my idle speed? or there is a lot more to it?

02EngineBay002-4.jpg

TIA

Hamada

70Bristol02 E36M3 E34535im

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Remember: If you adjust the idle speed of the carbs, do so in small increments on both carbs. Otherwise, they will be out of synch. when the throttle is advanced.

If the linkage is in a bind, it could be preventing the throttle shafts from closing all the way (on their stops), creating a false high idle condition.

To run correctly, both carburetors should open (their throttle plates) at the same exact time. This is why a good engineered linkage is so important.

Hope you plan on changing your oil (more) frequently now that you aren't running any air cleaners.

Good luck and report back on your progress.

Jim Gerock

 

Riviera 69 2002 built 5/30/69 "Oscar"

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Great info,

Norm, it was nice meeting you in person yesterday. Thanks for the tip. Looks like I will be heading to a learning "Adventure" with the carbs..which is cool.

Jim, Thanks :

I see this is going to take more than just what I thought. The first thing that I will need to tackle first, is locating a Pump Jet Cover that looks like it took off somewhere! I wonder if this have to do with that wacky idle speed..

I will do some more reading to learn about dropping the idle speed properly. Most importantly, I do not intend to run without filters. This is just short term until I get the carbs to run perfectly, then the proper filters will be on.

Hamada

70Bristol02 E36M3 E34535im

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Look at both carbs. One (maybe both) will have a screw in the hole I've

circled in red. Unscrew that in 1/8th turns, and if both are touching the adjustment

levers, unscrew both.

Be ready for things to go shitty. As you close the plates, it blocks off the

progression holes, and now you'll be running on the idle circuit, the mixture of

which I've circled in green. I've found that each barrel wants a slightly different

setting of these screws... which doesn't make any sense, but there it is.

Enjoy!

t

post-611-13667596071186_thumb.jpg

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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There is so much to look at here.

make sure you can adjust both carbs for how much they open. you should get a Syncrometer to adjust the airflow.

You can call me at 604 879 6288 if you like, during the day and I can explain to you a few things.

Overseas Auto

Vancouver BC

1-800-665-5031

always on MSN z5551212@hotmail.com

www.overseas-auto.com

www.weberjets.com

www.piaalights.com

www.thejimhilton.com

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Remember: If you adjust the idle speed of the carbs, do so in small increments on both carbs. Otherwise, they will be out of synch. when the throttle is advanced.

If the linkage is in a bind, it could be preventing the throttle shafts from closing all the way (on their stops), creating a false high idle condition.

To run correctly, both carburetors should open (their throttle plates) at the same exact time. This is why a good engineered linkage is so important.

Hope you plan on changing your oil (more) frequently now that you aren't running any air cleaners.

Good luck and report back on your progress.

I have a great feeling that my issue is related to the linkage not closing the throttle plates properly at idle. Rewind: I had an issue 2 weeks ago when my throttle was not opening more than 4.5k rpm highway speed and I could not even get to 90mph.

Looks like when the linkage was adjusted to give me the higher rpm, somehow it shifted the part that affects the idle speed. Does this make sense? I have a feeling thats what happened.

I already located a pump jet cap and put it on and that did not fix the idle (wishful thinking + noobness). So before I tackle the idle adjustment screw, I should examine the linkage.

Does that make sense to anyone here?

TIA

Hamada

70Bristol02 E36M3 E34535im

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thats right. disconnect the linkage from the carbs. Then see if the engine idles at whatever speed you want.

Ideally, you should be able to have the idle speed at 800 rpm or less, and then if you turn in the idle mixture screws, the engine will die. If you turn the idle mixture screws in and the engine does not die, then one carburetor is still open.

Overseas Auto

Vancouver BC

1-800-665-5031

always on MSN z5551212@hotmail.com

www.overseas-auto.com

www.weberjets.com

www.piaalights.com

www.thejimhilton.com

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OK Guys we got it fixed. It was the idle that needed to be adjusted. I learned first hand how to do it.

1) unscrew the sync screw in the middle so it would not touch the shaft.

2) Plug a synchrometer in one of the horns. While watching the idle speed, unscrew the idle screw very little and keep an eye on the synchrometer.

3) Plug the synchrometer in the second carb and repeat setting the idle screw to match the same reading from the first carb.

4) Screw the sync screw back so it can JUST touch the shaft.

Now where do I buy the synchrometer?

Edit..Got it. Its JC whitney..

This is the one we used yesterday:

G_14219G_SW_1.gif

Another question: They recommended a synchronizer to be used with the meter above. We didn't use this yesterday. Interesting device should I buy it too? Is it worth it? how does it work?

I_492173_SW_1.gif

Hamada

70Bristol02 E36M3 E34535im

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On the contrary, the second one with the floating ball (Unisyn) works just fine. Any device will work well, as long as it seals against the throat or velocity stack and offers an easy method of adjustment. The fancy one gives airflow readings (CFM).

The UniSyn can be used on both horizontal and vertical carburetors by rotating the tube. I've used mine with great success on my dual Dellorto 40mm VW carbs.

1) Disconnect the linkage

2) Hold tool tightly against open throat/velocity stack of carb. # 1

3) Using the thumbscrew, adjust the center orifice so that the floating ball is about in the middle range.

4) Move device to second carburetor and adjust idle to match the ball position from the 1st carb.

5) Re-connect linkage.

Additional fine tuning can be done using the tool between throats of the same carb.

Jim Gerock

 

Riviera 69 2002 built 5/30/69 "Oscar"

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