TheSamba.com :: View topic - Solex 35 pdsit accelerator pump nozzle placement question

Thu Aug 14, 2008 1:09 pm

I've done a lot of searching, but have not had any luck finding the answer to my question.
Dual solex 35 PDSIT. I got new jets and syncronized my carbs as per the AC.net tech page on syncronizing dual carbs. My bus is idling great, but I'm having a stumbling issue when I accelerate. It happens through all rpm ranges, and from what I have read, it could be the accelerator pump.
From the searching I have done, the placement of the accelerator pump nozzel on a 34 pict 3 carb is very important. I was wondering if it is the same on the 35 PDSIT, or, if the way they came from the factory is OK? Right now they look like they both hit the throtle plate about where the hole is in it. Would there be any benifit to redirect them to hit closer to edge of the throtle plate?
Thanks
Jeremy

Thu Aug 14, 2008 1:37 pm

I'm assuming thats setting the air flow with a sync tool and making both throttles open at the same time. They hit about 1/8 from the edge of the plate so it sounds like yours are close enough but it won't hurt to experiment. Did you take the tops off and check for the same jetting and any dirt in them. Have you tried leaner /richer idle and main jets? Does the vaccum advance work correctly? If its an 009 it may need to be overadvanced from 10-15 degrees at idle. It help to keep a journal to record progress or lack of progress.

Thu Aug 14, 2008 2:07 pm

since you are at 7k', back off the pump squirters a BUNCH and see if that helps. Usually they are set on "Mosquito fogger" setting, way too much fuel on the squirt, and it's even worse at 7k'.

I'll bet that helps a lot, and will help your MPG.

John
Aircooled.Net Inc.

Thu Aug 14, 2008 2:11 pm

Thanks for the reply.
I checked the airflow with a snail syncrometer. One carb read 7 kg/h, the other read 8 kg/h. I turned the 8 down to a 7. I also readjusted the linkage after I made the adjustment.
When I changed the jets, I fully cleaned all of the debris out of both carbs.
I have had other jets in the carbs, but the ones that are currently in there are recomended by John from ACnet based on his experience jetting for altitude. They seem to work great except for the initial exceleration.
Distributor is a SVDA and the advance seems to be working corretly.

I'm going to try Johns recomendation and see what happens. I just wanted to make sure I was on the right track before I started tweaking things. Improved mpg would be a nice bonus as well.
Thanks

Thu Aug 14, 2008 2:14 pm

one more tip. Before you turn one carb down or one carb up to syncronize, you need to put a vac gauge on the ports of the carbs. Remember, you should get 0 vac at idle.

If you get vacuum at idle, you must close the throttle plate. Also, you do not want to be too far away from the vac port at idle (which is a symptom of too much idle timing, like more than 9 BTDC).

It's critically important that you are as open as possible, while still 0 on the vac gauge. That will result in best operation. You can adjust the idle timing to get the idle speed where you want, without opening/closing the idle speed screws.

John
Aircooled.Net Inc.

Fri Aug 15, 2008 10:50 am

john@aircooled.net wrote: one more tip. Before you turn one carb down or one carb up to syncronize, you need to put a vac gauge on the ports of the carbs. Remember, you should get 0 vac at idle.

If you get vacuum at idle, you must close the throttle plate. Also, you do not want to be too far away from the vac port at idle (which is a symptom of too much idle timing, like more than 9 BTDC).

It's critically important that you are as open as possible, while still 0 on the vac gauge. That will result in best operation. You can adjust the idle timing to get the idle speed where you want, without opening/closing the idle speed screws.

John
Aircooled.Net Inc.
John,
Thanks for all the great information!
I'm working through it all and the results are positive.
Thanks again

Fri Aug 15, 2008 12:26 pm

I forgot to address the aim, yes they should hit the gap between the throttle plate and bore wall. They should NOT hit the plate directly.

John
Aircooled.Net Inc.