Thread: Series 2 Solex Carburetor

G'day,

The thread size for the Solex 40PAIO Banjo bolt into the fuel inlet is M12 x 1.25.
The Banjo seal to the housing will always be a problem with leaks on these old die-cast housings. The die-cast material (Zinc) softens with constant contact with petrol.

Chris

Originally Posted by Busted Syncro

G'day,

The thread size for the Solex 40PAIO Banjo bolt into the fuel inlet is M12 x 1.25.
The Banjo seal to the housing will always be a problem with leaks on these old die-cast housings. The die-cast material (Zinc) softens with constant contact with petrol.

Chris

Thanks Busted Syncro thats perfect.
soilandwater

this thread has solved a problem.... well found it at least.

When I read the answer above about M12.... I went away pondering as I have been dealing with a persistent leak from this fitting but MY banjo bolt is a Whitworth thread.

With a few minutes to spare today I whipped the cover off the carb and found a completely stripped thread that probably was metric once and has been bush fixed to whitworth... bugger.

I'm on the hunt for a new Solex top cover if anyone has one!!

Originally Posted by Cadas

this thread has solved a problem.... well found it at least.

When I read the answer above about M12.... I went away pondering as I have been dealing with a persistent leak from this fitting but MY banjo bolt is a Whitworth thread.

With a few minutes to spare today I whipped the cover off the carb and found a completely stripped thread that probably was metric once and has been bush fixed to whitworth... bugger.

I'm on the hunt for a new Solex top cover if anyone has one!!

PM sent.

G'day All,

I have had a few goes at stopping the leaks on the fuel inlet of the Solex 40PAIO carburetor over a 45 year period. After the banjo face ended up so distorted due to the die-cast material softening it would always leak with the hazard of fire, I tried two methods:

1. I re-tapped the M12 x 1.25 inlet (20.32 tpi) thread to 1/2" UNF (20 tpi). Then used a 1/2" UNF CAV filter hose adapter to use 5/16" Ortac hose.
This CAV adapter seals inside the housing at the end of the pilot hole. Just seat the fitting a few times to make the bevel in the now soft die-cast. This worked for many years however, would loosen up with a small leak.

2. I machined up an adapter with the same CAV filter end profile with a 45 deg inverted flare seat on other end. I then machined up a hose adapter 5/16" to 45 deg flare on the other end. A nut screws onto the CAV fitting to hold it together. Wire locked. To service the carburetor/hose just unscrew the nut. The other fitting is locked in the top cover. No more leaks.

3. As there is a spare un-threaded port on the top cover, seal the original port with a plug and tap the new port and spot face the housing. Hope I don't have to do this one!.


Pictures attached :

Chris

Similar idea

1/4” BSP.....



Mine is not as neat but it’s only temporary

Originally Posted by Cadas

this thread has solved a problem.... well found it at least.

When I read the answer above about M12.... I went away pondering as I have been dealing with a persistent leak from this fitting but MY banjo bolt is a Whitworth thread.

With a few minutes to spare today I whipped the cover off the carb and found a completely stripped thread that probably was metric once and has been bush fixed to whitworth... bugger.

I'm on the hunt for a new Solex top cover if anyone has one!!

hi i have comlpete 40 pa 10 jim

Cheers, I’m good at the moment, found a new old stock lid that’s on its way.