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 420041View 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.

 

[Tarlard]

Hello, back again. Time for a bit of a rant and many questions. (Sorry in advance)

I've driven 20-30km a week since the last post (mostly 60km/h roads) (I haven't dared take it on the highway yet due to the weather over here). The driving experience has mostly been fine, but this morning when starting the car it only ran on one cylinder: The front cylinder (the one closer to the front of the car) was flooded.

What baffles me is two things.
Firstly, when the car floods (it has never done this on the original carburettor, even when that one started leaking fuel) it is always the front cylinder that will not fire. Swapping plug cables doesn't change anything.
Secondly, no matter how much I clean and dry the plug of this cylinder, it refuses to fire until it gets a completely fresh plug. It seems that the spark plugs are actually broken somehow. I've went through like 4-5 plugs at this point on this one cylinder. I am planning to buy a plug tester to figure out more.

For reference I use NGK BP7HS plugs and have new sparkplug cables.

I'm wondering about the following:
Could the car still be too rich?
Do I have the wrong heat range for my plugs. (This one would be weird for me as the car has always run completely fine with the non leaking stock carb)
Why is it always the front cylinder that stops working? Is this a known flaw or could there be something wrong with my engine?
Could I perhaps have a weak spark and need a new coil? (This one also seems weird to me, as the rear cylinder works perfectly fine)

I also have some more plug pictures (Which are probably useless due to the flooding)

Thanks in advance for any advice.

 

[Tarlard]

Quick update. I have found that the ignition breakers points were out of spec, so I fixed that. Also the spark plug cable of the misbehaving cylinder was loose at the coil, which has also been resolved. I have also widened the spark plug gaps to the upper end of the spec 0.7mm instead of 0.6mm.

I will run the car like this and see how it goes.

 

[bugsymike]

Quick update. I have found that the ignition breakers points were out of spec, so I fixed that. Also the spark plug cable of the misbehaving cylinder was loose at the coil, which has also been resolved. I have also widened the spark plug gaps to the upper end of the spec 0.7mm instead of 0.6mm.

I will run the car like this and see how it goes.

When you say points out of spec. were the contacts blue and pitted? If so it points to a fault condensor.
Should misfire reoccur try having a look at the missing engine in the dark to see if and leads or coil shorting.
By the way the wider the plug gap beyond recommended setting the more voltage the coil has to provide to make the spark jump the plug gap, so then more likely to take the easy route and short/breakdown.

 

[Tarlard]

Thanks for the advice about the plug gap. They are still within spec. I'll have a look at the engine in the dark to see if there are any sparks anywhere.
By points out of spec I meant that the points were too close to eachother. Otherwise they looked completely fine, because I only replaced them a couple hundred kilometers ago. No pitting or blue coloring.

 

[Tarlard]

Hello again, I'm turning this somewhat into a journal at this point, haha. Hopefully this thread can help someone attempting the same swap some day.

Anyway another update:

The car has been running fine for a month, but the mileage was a bit mediocre 8 km per liter!!. I had a look at the chart again and decided to buy a smaller pilot jet and a smaller pump jet. Had a couple of drives with those jets now and the car is still running good. (Haven't calculated fuel mileage yet) Decided to check the plugs again today and I think they look great. Judge for yourself:

This is still with a 100 main jet, but now a size 40 pilot jet and a size 35 pump jet.
I'm not the greatest plug reader, but I feel this is good or ever so slightly lean.

I'm going to try out a 102 main jet for a bit and see how it goes for the heck of it.

Goodbye

 

[bugsymike]

Hello again, I'm turning this somewhat into a journal at this point, haha. Hopefully this thread can help someone attempting the same swap some day.

Anyway another update:

The car has been running fine for a month, but the mileage was a bit mediocre 8 km per liter!!. I had a look at the chart again and decided to buy a smaller pilot jet and a smaller pump jet. Had a couple of drives with those jets now and the car is still running good. (Haven't calculated fuel mileage yet) Decided to check the plugs again today and I think they look great. Judge for yourself:
View attachment 422409
This is still with a 100 main jet, but now a size 40 pilot jet and a size 35 pump jet.
I'm not the greatest plug reader, but I feel this is good or ever so slightly lean.

I'm going to try out a 102 main jet for a bit and see how it goes for the heck of it.

Goodbye

I tend to agree , just going slightly on the lean side.