Author Topic: Solex Carburettor  (Read 1386 times)

Offline DennisM

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Solex Carburettor
« on: January 14, 2017, 02:50:36 PM »
I thought last year was bad enough, I named it the year of 'The Battery' as I had 5 batteries die all very close to one another, this year so far it has been the year of the Solex Carburettor.
My S2A 109 Ambulance had the carburettor rebuilt at a well known place and it cost quite a few bucks to boot, I bought a rebuild kit off the net which stated it was for a B40PA10-5 Solex which is what is fitted as a standard carburettor for the S2/2A 4cylinder engines, anyway I thought the motor was running OK but out n about it was dead as, pull allright on flat ground, went downhill like a rocket (probably because of it's own weight LOL) uphill/slope it just died, going back through the gears++ holding up traffic, so I decided ti was time fro a L/R mechanic to give it the once over, off I went to Dungog.
The ignition timing was good, tappets OK, plugs OK a quick fiddle with the carby and off we went, but it still died on hills no matter what was done, it would rev freely/quickly without hesitation, but it was too lean at high rev's and that caused a small backfire through the exhaust.
It was suggested that I try another Solex, well it just happened that I have other Solex units including 2 rebuilds (done by the army) they were bought in a town way up in the states Nth west, they were still in their heavy duty plastic bags sealed with the EIME sheets, but I had fitted both these units to a couple of my fleet, so I took it off 112-587 (Wee-Wullie), fitted it up to the suspect vehicle took it for a drive, it went a hell of a lot better, so what I was told in Dungog was that it was starving for fuel under load and that the problem was most likely associated with the carb rebuild, well that seemed to be the case.
In the meantime I had corresponded with Dave F aka Blknight he advised to check the fuel pump as well, to be honest I had not thought of it being an issue, anyway I disconnected the fuel line to the carb, and put in place a line into a container, the engine ran for approx 40 seconds then stopped, the pump had put approx 700/800 mls of fuel into the container just like Dave said, I went to collect my camera and came back to find the fuel container had over flowed and fuel was everywhere, alarmed as I was about the fuel spill it also told me that the pump's valves were most likely faulty, so off to buy a new pump, which was duly fitted and taken for a run with 112-587's Solex still on it, well the pump made a difference not quite F1 performance
but it was way ahead of how it was in the 1st instance, so I quickly changed carbies again took it for a run, the performance had dropped off quite a bit, it was still better than it had been, so this got me thinking about the kit that was put through it.
Today after lunch in the heat 39c in the shed, I still had 112-587's carb on the bench, armed with the parts book I took different jets out 1 at a time and checked the against other carbs and the book's spec's.
Here's what I found
Pt No 47 Main Jet should have 120 stamped on it, it didn't so I swapped it out.
Pt No 39 Accelerator Jet 50 stamped on it the hole in it should be 0.098" the new one was much smaller @ 0.82", it was swapped as well
Pt No 53 Starter Jet 145 stamped on it, the hole on a original jet is 0.116" dia, the one I took out was 0.070" quite a bit smaller as you can see in the image
anyway it's all back together, it starts/revs etc, but it will have to wait until tomorrow before I take it for a run, too hot to be untarping 2 Land Rovers and moving 100 lts of fuel in 5 x 5 gallon jerry cans, yeah I'm getting lazy/older  LOL I'm hoping that it will go OK wish me luck, cheers Dennis

Offline Philthy

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Re: Solex Carburettor
« Reply #1 on: January 14, 2017, 05:57:24 PM »

For such little things done right you get big results.
There is a wonderful tuning tool called a glass sparkplug (old school before gas sensors) for getting the mixture just right. Gunson colourtune in England still make them. They are spot on. Also, jetting should be done with a good air and line filter fitted for correct mixture tuning as you would know.

Good luck with it. Phil

Offline Mick

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Re: Solex Carburettor
« Reply #2 on: January 14, 2017, 09:30:56 PM »
Good luck Mate 👍😎