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Spits and Sputters from Dual Solex 40PHH's

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1970 2002 PROJECT

  • 1975 block
  • 1983 head
  • dual Solex 40PHH's probably from a 2000CS (Yes, I know they are old-school and make some exclaim "AAAGGGHHH".
  • 123 ignition


Except for the following, the car is reliable and fun to drive: 


Car reliably, predictably, and reproducibly spits and sputters through the carbs ONLY at a constant rpm and low speed.   Imagine driving down a typical suburban avenue, just peacefully cruising along at, say, (1) 2nd gear, 2,500 rpm, 30 mph or (2) 3rd gear, 2,000 rpm, 30 mph...erratic spit, sputter, sputter, spit, spit...out the carbs, not the tailpipe. 


Car idles smoothly at 800-1,000 rpm.  No spitting.

Car accelerates smoothly and strongly with no flat spots.  No spitting.

Car decelerates smoothly.  No spitting.

Plugs are dry and tan.

new plugs and wires

Carbs do not leak.


Here is what I have done to address the issue over the last several months:

1.  rebuilt the carbs (no jet changes; throttle shafts are tight)

2. adjusted float levels 3 time (used BMW tool 6023 to do so)

3. tried >40 advance curves (from virtually no advance to ridiculously high advance; 2002, 2002ti, 2002tii curves and curves I invented)

4. adjusted valves

5. sprayed propane and brake cleaner in all likely air leak points numerous times - no obvious leaks

6. balanced carbs' intake volumes 

7. AFR at idle, cruise, and WOT are within recommendations of several FAQ'ers

8. tweaked/adjusted the idle screws over and over and over

9. installed completely new fuel supply system - fuel tank to carb inlets


NOTE:  Yes, I know 90% of all fuel-related issues are in the ignition system.


I hereby present my issue, will very much appreciate your kind mercy, sage advice, and wise counsel, and am willing to be subjected to your exceedingly high contemporary standards.  


Let the beatings begin...







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THIS is why I frequent the faq.      Great info, and it doesn't evaporate moments after it's typed.       jb

I've never done that, but wouldn't adjusting the idle speed to 2300rpm take the carbs off the mixture circuit and the mixture screws wouldn't have any effect? My Solex books speak much the same as to

1970 2002 PROJECT 1975 block 1983 head dual Solex 40PHH's probably from a 2000CS (Yes, I know they are old-school and make some exclaim "AAAGGGHHH". 123 ignition  

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I agree with Ed, but can you reproduce the problem with no load- with the car not moving, just adding throttle?  What's the AFR doing when it's sputtering?


I ended up going with 53s for the idle jets.



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Many years ago I installed the PHH Solex carbs on my 1600, but it took me some time to sort out some of the issues. One issue was that I wasn’t using the original gaskets and spacers between the carbs and the manifolds. I was using some aftermarket o-ring spacers- gaskets designed for Weber’s. And, these things were leaking air as they don’t work with the PHH carbs.

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1 hour ago, Hans said:

What are you using for air cleaners? I seem to recall my phhs changing slightly with the air box attached.

 Yes, once tuned with the airbox, mine hate running without the ti airbox.  Lots of spitting and misbehaving.

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Sidedrafts are very fickle like most carbs except in this case you have 4x the number of variables compared to a single downdraft. Another thing I noticed is that the venturi size plays a large role in tuning and jet selection. The factory set these carbs differently for the 1600ti, 1800ti and 2002ti. Many people grab carbs from one model and attempt to adopt them to another model. The 1800ti comes to mind as many of these cars were imported into the US. And, people sell the carbs while falsely advertising they will fit all M10 engines. Well, they will fit, physically, but they are jetted differently and have specific venturi sizes for the three different engines mentioned above. The 1600ti specific PHH carbs are the rarest of the bunch while the 1800ti and 2002ti are more common. Venturi sizes vary; 30mm for 1600ti, 32mm for 1800ti and 34mm for 2002ti. This is your starting point.

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Ed, Slavs, Jam3422, and Hans, 


Thanks so very much for your timely responses.  I will start tomorrow looking into your many thoughts, comments, questions, and suggestions and then respond re: jet and venturi size, performance wlthout load, gaskets, leaks, etc. 




NOTE:  Others continue to be welcome and are encouraged to respond to my automotive mental, physical, emotional, and spiritual Black Hole.

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Posted (edited)

Why the zip tie on the dizzy? 


Can you take a screen shot of your advance curves,  include the vac curve please. 


Have you changed your dizzy rotor from the original one?   What model dizzy did you get?


If you changed out the rotor for any one other than the original one that shipped with the dizzy it may be the problem.  There are a bunch that look the same, and kinda fit the same, but they are different.  What happened to me is the I.E resistor rotor felt like it was seated, but it wasn't.  it would come a bit loose and be sloppy on the shaft, It wouldn't come off, but the cap would wallow around, and get worse with higher revs. 


I ended up using a bit of grey permatex to "glue" a resistorless rotor in place.  I had no option because I was running a MSD with low resistance wires( as per MSD spec) and the rotor blew up ( as you can see), as a result of the resistor melting down. 


So far it works just fine.  Although I will be replaced with a COP or sequential when I go to a turbo program. 






Edited by Dudeland
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On 5/27/2021 at 2:13 PM, Jam3422 said:

 Yes, once tuned with the airbox, mine hate running without the ti airbox.  Lots of spitting and misbehaving.


My car seems to run the same with or without the ti air box.  More intake noise without it..

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Well, good example of YMMV. Its been many years since i ran teh Solexes, but that is my recollection. That said, this sounds a little different. We await update from OP. 

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