Solex Carburrettor 30FFA1

RobHomewood
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Solex Carburrettor 30FFA1

Post by RobHomewood » Tue Aug 09, 2022 12:13 pm

I ahve been trying to understand the bi-starter on my 30 FFA1 Carb. Is it correct that when the engine is warmed up and the choke fully home that air is still being drawn in via the starter air jet? When I put my finger over the jet the engine stops so its not a little amount of air. The carb is as supplied complete after refurbishment and looking at the bi-starter disc I cannot see a different way it could be fitted to close the air off.
Perhaps someone could explain it to me?
Thanks
Rob
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luli
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Re: Solex Carburrettor 30FFA1

Post by luli » Tue Aug 09, 2022 5:10 pm

It shouldn't be like that. Have you tried to turn the disk 180 deg? or flip it over? I have found some defective bodies that suffer from this issue and I had to scrap them.
See more here:
https://lulis.org/2014/07/19/%d7%a8%d7% ... 5%d7%a8-3/
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
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David2021
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Re: Solex Carburrettor 30FFA1

Post by David2021 » Wed Aug 10, 2022 11:17 am

Perhaps a little off topic, but I will join in!
My p2 tourer on arrival with me has a 30FAI marked "12HP" and LK61. I acquired another 30 FAI also marked 12HP, but LA68. It came from a saloon I and had very little sign of wear. Has anyone any idea what the difference /significance of LA68 vs LK61 might be? All the jets are the same.
I have in fact taken the top from the LK61 and put it on the LA68 as the body of the LK61 was a bit distorted by one of the bolts and the this gave me the best pair of threads.
It is now on the car.- I have yet to "tune" this unit, but it started & runs well.
I regard the functioning of the Bi-starter as a bit of a black art and leave mine well alone! I have yet to get the choke light to work.....

RobHomewood
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Re: Solex Carburrettor 30FFA1

Post by RobHomewood » Wed Aug 10, 2022 12:01 pm

Thanks Luli
When you say 'it should not be like' that did you mean the main carb body or the bi-starter unit with disc?
I looked at the parts photo in your link and I see there is a paper gasket shown. Bearing in mind that mine is a 30 FFA1 (twin choke) rather than a 30 FA1, Is this gasket supposed to be between the bi-starter and the main body? As I dont have any gasket at all. If it is do you have a source or a template please?
I tried turning the discs thro 180 deg but then the notches for the operating steps would not meet the ball bearing so that was wrong. Unless the outer disc only was installed the wrong face round. I might try that.
Thanks David 2021. I too did not want to delve into the black arts of the bi-starter and I presumed it had all been set up right when I bought it refurbished at great expense. However the car has always struggled up hills and my efforts to resolve this have largely been ineffective. I am going on a tour next week and trying to get the car in the best shape. Hence the concenr about the air inlet being constantly open which must affect tuning surely?
regards
Rob

RobHomewood
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Re: Solex Carburrettor 30FFA1

Post by RobHomewood » Wed Aug 10, 2022 5:20 pm

I removed the bi-starter again to reverse the pierced disc but I could not see how to remove the disc from the shaft. I didnt want to force it off as it probably wouldnt stay on when replaced. Any ideas?
Rob

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luli
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Re: Solex Carburrettor 30FFA1

Post by luli » Thu Aug 11, 2022 5:16 pm

Hi Rob,
There is no paper gasket. What you saw is the gasket between the carburretor body and it's bottom section. just make sure that the surfaces are flat and there are no scratches. In a well functioning carburretor you should be able to tune the engine to a very low RPM and no air draw from the bi starter air jet. If this is impossible then the body is damaged.
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

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luli
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Re: Solex Carburrettor 30FFA1

Post by luli » Thu Aug 11, 2022 7:19 pm

A little gentle force. Take the opportunity to clean and polish it. BTW a friend of mine purchased the same carburretor, for 50 pounds from Freddy Boulton. Excelent condition. May be he has another one.
Rover 10 1946 RHD
Rover 10 1947 LHD
Rover 12 1947 tourer LHD
http://lulisml.wordpress.com/

RobHomewood
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Re: Solex Carburrettor 30FFA1

Post by RobHomewood » Fri Aug 12, 2022 8:01 am

Thanks for that Luli. I will try that today.
In the meantime are you able to confirm whether there should be a paper gasket between the bi-starter and the main body of the carb and if so is it the one in the bottom left of the photo on your link? I am now getting anxious becasue we leave on Tuesday and time is running out! I could try to copy that even though the 30FFA1 may be slightly different.
Any input from anyone else also gratefully accepted
regards
Rob

RobHomewood
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Re: Solex Carburrettor 30FFA1

Post by RobHomewood » Fri Aug 12, 2022 9:26 am

Hi Luli
Sorry I have only just seen your other response about the gasket- I think it must have been delayed somehow
regards
Rob

RobHomewood
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Re: Solex Carburrettor 30FFA1

Post by RobHomewood » Fri Aug 12, 2022 11:20 am

Hi Luli
I have been looking long and hard at the photos of the bi-starter disc etc and concluded that I cant reverse the disc because the holes would be in the wrong sequence. My thinking is this: the the large rrounded rectangular hole is the air vent. Opposite this on the disc is a medium size round hole which corresponds to the round hole in the body and is the full choke. Next to it is a smaller hole which comes over the round hole in the body at half choke. There is a second medium size hole somewhat isolated which I dont understand. If I reverse the disc then the small hole would equate to the full choke position and the medium hole to the half choke because the disc is always turned the same way by the lever. Please comment if you think I have got this wrong.
What I suspect now is that the disc is not sealing against the body apertures fully and air etc is leaking to the wrong areas. This is perhaps evidenced by the dirty staining around the air hole in the disc. The spring seems pretty strong so maybe not that. I shall polish up the disc and the mating body faces and see if I can get a better contact.
I look forward to any comments on this
Rob

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