Solex PID 40

[sporadic_haf]

Hi Guys

I am just new to the forum. I have two Polycab haflingers (1965 SWB and a 1973 LWB).

One has a Solex PID 40 carb. I am struggling to get it to run properly. It appears to be leaning out and spitting through the carb when revving midway between idle and full throttle. This is particularly the case under load. The truck is simply undriveable.

I can't find any evidence of vacuum leaks and compression is good. Valve clearance also checked. All ignition system components have been changed/replaced and timing set to spec (also tested slightly more advanced timing) all with no joy.

I was wondering does anyone have any experience of this carb. I suspect a blockage somewhere in the bypass circuitry and have tried ultrasonically cleaning the carb (twice now!). Still no good!

Any thoughts?

Kind regards
Darren

[AustHaflinger]

I had a Solex 34 on my Haflinger when I bought it - it ran but not well and I could never get it sorted as nothing stayed consistent - so I changed back to the proper NDIX 32 carb - fixed the issue.

[heinkeljb]

Does it run any better with the choke being used? Have you tried changing the jets?
Fuel octane rating can also play it's part - have you tried a higher octane rating either just from the pump or using a additive? Liquid fuel can change the shape of the jets - think grand canyon on a smaller scale. If the Carb is not well suited to the engine it is fitted to then everything is more of a compromise.

Have you tried swapping the Inlet manifold and Carb from the LWB to see if the engine can actually run nicely? Maybe long term a replacement Inlet manifold and Carb would be the way to go if the above works.

If you want to continue with your Solex.

Buy a can of compressed air if you haven't got access to a compressor and dismantle the Carb. Then blow air down every single hole you can find, the higher the pressure the better.
Then try you ultrasonic cleaning again. New jets if you can get them would not go amiss.

Good luck,

John

[sporadic_haf]

Thanks Guys

I have ordered a new larger main jet for the carb. I will try this along with trying a bit of additive in my fuel. I know some of the history of this truck and know the last person who ever owned/drove it. This was back in the late 80's when the older system of leaded fuel was being used in the UK (I know the lead has nothing to do with it but the octane level was different too). .

Interestingly one of the things that this gentleman did tell me was that as well as the truck running well then it also was extremely fuel efficient. I am not an expert in fuels but this does make me tend to think that this carb as jetted (112.5 main jet) was perhaps already running quite lean. Perhaps this was compatible with the fuel back then but not with todays standard fuel from the pump.

With regard to a new carb. I do have a spare NIDIX 32 but of course the manifold is different. I see i can purchase one for about 300 Eur from Autquariat. So this will be my back up plan.

Before I go down that road I will look at taking the manifold off my LWB. I am a bit reluctant to disrupt it though as one side of the heater pipe is looking quite fragile.

Thanks for the input so far. I will report back on any success with the re-jetting and octane boost!

[sporadic_haf]

Folks

A quick update..

I replaced the main jet (112.5) with a new larger jet (125). The truck drives well now. Idles well and accelerates well.

I do want to go back and try the 112.5 jet again at some point just to make sure that definitely was the problem but it does look like it.

I have another issue now in that, after driving around a bit (a few miles), I have one plug that looks carbon fouled and one that looks very very white (looks hot/lean). Need to do a bit more fault finding on that issue. Compression is 125 PSI on each cylinder. I can't find any vacuum leaks. The truck will idle on either cylinder (with other plug lead removed) but it does seem to idle slightly better on the lean looking plug/cylinder.

Getting there..

d

[heinkeljb]

I would take the whole manifold off and check that the pipes are clear and approximately the same size, it one side has a restriction that would give you uneven running. Also check the valve clearances, you might have good compression, but if the valve is not opening properly, that also affects running.

While your at it, check the ignition circuit, from the coil to the plugs. Coil, HT leaded, timing, points, condenser etc.

John

[AustHaflinger]

Hi Darren,

You say you have a Solex PID 40 on your haflinger. That is an awfully big carby to have on a such a small engine. You have a 40mm throat carb to deal with each cylinder capacity of 320cc. A 4 cylinder, 2 litre land rover engine only has a Solex PID 32 on it so a 32mm throat to deal with an individual cylinder size of 500cc and it provides more than enough fuel.

My Haflinger is 763cc and when I bought it, it had a Solex PID 34mm carb on it, so dealing with a cylinder size of 382cc and that 34mm carb was able to feed my larger engine and push the Haflinger to over 85kph.

So my point is that a 32mm/34mm sized carb is plenty big enough for a carb, so if were your, I would investigate whether your 40mm carb is just too big. As it sort of runs you car at the moment, my guess is that it had been jetted right down and may be OK - I dont know - but something to think about.

Garry

[sporadic_haf]

Thanks again guys.

With regard to the carb size. I am not a carb guy so you will have to excuse my ignorance. However, I am not really sure what the '40' truly means in the name of this carb or if this 100% correlates to the actual capacity of the carb.

Specifically I have found some old documents (for the steyr puch invacar engine) where this carb, whilst it's called a 40 PID, is actually described as a "32" diameter carb with a 25 Venturi.

Also, more generally, it seems that this carb wasn't uncommon on steyr-puch engines - even the 500cc. Not usually on haflingers but much more familiar on cars. You will see evidence of this at the likes of the Prokschi website where parts are readily available for purchase.

Nevertheless something is still not right and I have a bit more fault finding to do. Whilst the bigger jet has given me a truick that I can drive it is entirely possible that i am just compensating for some other issue with the fuel supply.

Will keep working on it...

[AustHaflinger]

Darren - certainly not suggesting the carb is wrong for your use but something to consider - certainly a 34 is a "bigger" carb than a 32 and a 40 us bigger again. But if it works then that is great. I cannot comment on other Puch engines as I know nothing about them.

As I said, not suggesting anything is wrong just that you might want to look at it. Certainly with my Solex PID 34, I could not get it to run consistently so went back to the NDIX - but I very much know this can be a very expensive exercise.

Good luck with it.

Garry