Technical Issues running a Solex PBIC 32 carburetor

[Tarlard]

Hello, I have some questions regarding the usage of a Solex PBIC 32 on a stock 650cc engine.

I came across some cheap parts and decided to try it out. I have currently fitted the carburetor on the engine and have it idling, albeit a bit poorly. From what I could tell the engine was running rich.

I took of the carburetor and noticed that the intake manifold was coated in gasoline. My best guess is that this is due to the acceleration pump injecting more fuel than the engine can take in. I've been trying to find information about jetting sizes for similar setups, but have only found some references to the Abarth 695SS using a Solex PBIC 34, no jet sizes.

I was wondering if anyone here has experience with similar setups and could give me a clue about jet sizing.

Thank you in advance.

 

[bugsymike]

Hello, I have some questions regarding the usage of a Solex PBIC 32 on a stock 650cc engine.

I came across some cheap parts and decided to try it out. I have currently fitted the carburetor on the engine and have it idling, albeit a bit poorly. From what I could tell the engine was running rich.

I took of the carburetor and noticed that the intake manifold was coated in gasoline. My best guess is that this is due to the acceleration pump injecting more fuel than the engine can take in. I've been trying to find information about jetting sizes for similar setups, but have only found some references to the Abarth 695SS using a Solex PBIC 34, no jet sizes.

I was wondering if anyone here has experience with similar setups and could give me a clue about jet sizing.

Thank you in advance.

Wouldn't have thought it was an accelerator pump issue as that only operates as you press the pedal , not if held in one position.
Are you sure float height and needle jet OK. If not that then main jet size?
Found this on eBay listed for that carb on CJ Jeep or x two for a certain Porsche so presumably large jets. Don't know how these compare with yours.
Do you know it was fitted on a small Fiat originally?
I was once borrowed a twin choke Weber and manifold for a sporty mini and put it on an old Morris Minor I had, it went very well , but was so badly worn I used the same amount of fuel in one night that I normally used all week! So it was quickly returned.

​	32 mm​
Luftrichter​	Buse d'air​	Choke tube​	23​
Hauptdüse​	Gicleur d'alimentation​	Main jet​	125​
Luftkorrekturdüse​	Ajutage d'automaticité​	Correction jet​	220​
Leerlaufdüse​	Gicleur de ralenti​	Pilot jet​	50​
Leerlaufluftdüse​	Gicleur d'air de ralenti​	Idling air bleed​	​
Mischrohr​	Tube d'émulsion​	Emulsion tube​	​
Schwimmernadelventil​	Pointeau​	Needle valve​	1,5 mm​
Swimmer​	Flotteur​	Float​	12,5 g​
Einspritzrohr (Niedrig)​	Injecteur de pompe (Bas)​	Pump injector (Low)​	​
Pumpendüse​	Gicleur de pompe​	Pump jet​	55​
Ende des Pumpenhubs bei einer​	Fin de course de pompe pour​	End of pump stroke for​	​
Öffnung der Drosselklappe von​	ouverture de papillon de​	throttle opening of​	​
Starterluftdüse​	Gicleur d'air de starter​	Starter air jet​	4 mm​
Starterkraftstoffdüse​	Gicleur d'essence de starter​	Starter petrol jet​	​

 

[Tarlard]

Thank you. I have found an old pdf that states this carb was used on some variant of a 595 or 695 fiat abarth:

I'll be comparing the jets I have tomorrow if I have time and share what I have.

 

[Tarlard]

Okay so I have checked the jet sizes as they are in my carburetor (next to the abarth sizes from the internet for ease of reading):

	My carb	Abarth 595	Abarth 695	CJ Jeep
Choke Tube (Venturi?)	22	28	30	23
Main Jet	135	110	120	125
Correction Jet	190	200	160	220
Pilot Jet	50	45	45	50
Idling Airbleed	unmarked	130	130	-
Pump Jet	50	40	40	55
Starter Fuel Jet	125	80	80	-
Starter Air Jet	3.5	4	4	4
Pumping Injector	??	50	40	-

Supposedly the carburetor I have came of a Peugeot 403, which has either a 1.3L or 1.5L engine. So I assume I'll have large jets.

What stands out to me the most is the big difference in starter fuel jet when compared to either the 595 or 695. Could this explain the fuel soaked intake manifold? That is my best guess. I'm not sure how much the 0.5 difference in the starter air jet would make.

My main jet is also substantially bigger, but I did not notice any issue revving the engine under no load. I'm not sure how the smaller venturi plays into all this, as the Abarths do have significantly larger venturis. Then again the abarth jets are for the larger variant of this carb the PBIC 34, whilst I have the PBIC 32. Same goes for the correction- and pilot-jets.

Probably the best next step for me is getting a smaller starter fuel jet and main jet. Unsure about the other jets. Any advice?

 

[bugsymike]

Not an expert on jetting carbs, but I would say try to get nearer the Abarth with similar engine capacity as a rough guide, especially the main jet and if you can get the others so much the better. Jetting to a certain degree is trial and error depending on state of tune etc. Ideally on a rolling road.
Regarding venturis size personally I have found smaller gives quicker low down response and larger more top end power.
As I mentioned earlier check carb not flooding / float level etc.

 

[Tarlard]

Yes, thank you for the advice. I will check the flooding and float level and will order jets accordingly. Will update once I have some results for future reference.

Thanks again.

 

[Tarlard]

Hello again,

I have resolved the following issues: Float needle was leaking and float level was too high. The carburetor is now no longer leaking fuel. I have installed the 80 size started jet and 115 main jet.
Following this I tuned the car at idle and got it to idle very nicely now. I also did a test drive which for the most part went fine, except that my top speed is now only 80km/h instead of 110km/h (oops). I checked the plug and it looks like the car is running rich at higher rev ranges (at least to me), due to the carbon deposits:

I'm planning to try out some smaller jets.

 

[bugsymike]

Hello again,

I have resolved the following issues: Float needle was leaking and float level was too high. The carburetor is now no longer leaking fuel. I have installed the 80 size started jet and 115 main jet.
Following this I tuned the car at idle and got it to idle very nicely now. I also did a test drive which for the most part went fine, except that my top speed is now only 80km/h instead of 110km/h (oops). I checked the plug and it looks like the car is running rich at higher rev ranges (at least to me), due to the carbon deposits:
View attachment 418849

I'm planning to try out some smaller jets.

To me the soot is around the edges like it is being burnt off from earlier, the ceramic/insulator doesn't look excessively rich to me, but check on some plug maker guides to get a better picture.
I would warm it up and give it a hard run then put your finger around the tail pipe to see if any soot after that.
People used to test by going for a hard drive then dipping the clutch and switching engine off as they coasted to a halt, then pulled the plugs out for inspection.
Only do that if you feel safe to do so.
If anything I would probably try a larger main jet, but it may be a good idea to compare with jetting sizes from other members on Forum.
Do you have a friend at the testing centre that can put the probe up your exhaust and tell you if it is running rich?
Have you run it since with your original 135 main jet but not flooding?

 

[Tarlard]

I have not yet tried the original 135 jet yet. So I'll be doing that first before ordering any other jets.

I don't feel comfortable turning off the engine while at speed so I won't be doing that. I can ask around if I know someone with an exhaust probe (or if someone knows a guy)

Will try to update soon.

Thanks again!

 

[Tarlard]

Hello it has been a while; many jets have been tried and things seem to be going well. I tried going up in jet size, but it only got worse, but once I started going down from 115 the car started to pull better.
Here are a few plug shots (text is jet size)(unfortunately I forgot to take pictures for some jet sizes):

I believe the 100 jet size looks more or less fine, so I think I am going to leave that one in for a longer testing period.

Any opinions?

 

[bugsymike]

Hello it has been a while; many jets have been tried and things seem to be going well. I tried going up in jet size, but it only got worse, but once I started going down from 115 the car started to pull better.
Here are a few plug shots (text is jet size)(unfortunately I forgot to take pictures for some jet sizes):
View attachment 420041 View attachment 420042
View attachment 420043

I believe the 100 jet size looks more or less fine, so I think I am going to leave that one in for a longer testing period.

Any opinions?

The last pic doesn't look too bad. What sort of journey did you do to test, fast slow , motorway, town.
If you intend doing high speeds for a length of time I wouldn't go much smaller in jet size as if running too weak it can overheat the plugs and even burn holes in pistons in extreme cases.
Many years ago as a youngster I raced a Kart at Thruxton Racing Circuit, I was sharing the race events with another driver and as he was experiencing it running too rich and fouling the plug we had put a smaller main jet in, unfortunately we didn't fit the larger jet for my race, which shall we say I gave it a little more accelerator, the result was the engine got hot and seized so that was the end of that race meeting .

 

[Tarlard]

The route was firstly some town driving 30-60km/h, followed by some 80km/h driving (about 2km), and finally a short 60km/h bit home. I'm planning on keeping the 100 jet in for now and doing a longer high way test (hopefully some 100km/h driving)

 

[bugsymike]

The route was firstly some town driving 30-60km/h, followed by some 80km/h driving (about 2km), and finally a short 60km/h bit home. I'm planning on keeping the 100 jet in for now and doing a longer high way test (hopefully some 100km/h driving)

Should be fine, but if not sure , then wise to inspect plugs occasionally.