Carburettor gasket

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Darren2030

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Hi fellas

Just after a little advice on carburettor base gaskets I’ve got a single port engine with an original solex 31 pict 3 and an adapter to clear the alternator. I keep getting a leak from underneath the carburettor it seems to be coming from the top gasket on the adapter when I removed them they were soaked in petrol and I pretty sure it’s where it’s coming from,
The question is does anybody use any type of sealant on the base gasket’s as they do seem quite thin!?

Cheers
 

purpledog07

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Hi Darren,
Has this only been fitted once? Most gaskets are one time use only, as they deform to make the seal on crushing. If removing and refitting then buy or make a new gasket.
Normally sealant is not used for carbs or fuel pumps as petrol attacks most silicone or PU based sealants. Sealant can also block channels.
I've always used thick gasket paper to cut gaskets from and never had a leak.
Gasket paper is usually available at local car shops or online.
If you have to use a sealant then use Blue Hylomar gasket sealer, spread thinly then wait until it starts to dry before fitting.
Worth checking both mating surfaces are dead flat too, file or sand off any casting ridges/imperfections.
If it's really not having it then one tip is to make two gaskets and sandwich them using a thin layer of Blue Hylomar spread on one gasket.
Hope this helps.
 

Darren2030

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Hi mate

Yes they were two new gaskets and to be honest they were very thin and don’t think they were up to the job come from a well known company and not cheap! I’ve just bought another two from a company in Germany which are a lot thicker and look more like it I just didn’t want to put them on and same thing happened again (paranoid lol) I’ve never had this problem b4 with the spacer either but I will double check it make sure it’s flat and smooth top and bottom and also will double check the manifold surface but pretty sure they are all good bud, would you reckon a little bit of grease would help or like you say just fit em dry!?

Cheers
 

Darren2030

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Thanks for you reply’s fellas much appreciated and helpful as always I’ll fit them dry and make 100% sure everything is nice and clean, as I said earlier these other gaskets look a lot better and more like giving a much better seal!

Thanks again
 

purpledog07

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I agree, dry fit, no grease on fuel pumps, carbs etc.
If sanding or filing be sure to block any holes where the metal dust/filings might drop into the manifolds and then the cylinders, remove to sand if you can to be on the safe side.
Good luck.
 

Moseley

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Just a thought, I wouldn’t expect carb gaskets to be soaked in petrol - it might be that you’re trying to solve a gasket problem, but actually the issue is that your carb is leaking fuel when the engine is switched off.

The intake should only see atomised fuel, and the gaskets shouldn’t be subjected to more than this. If it is visibly wet, then this will not be doing your pistons and bores any good as the petrol will be washing away the oil film.
 

Darren2030

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Hi Moseley

I can see your point mate yes i ain’t no expert but I can’t seem to see any other place on the carburettor where it could be leaking from, I originally thought it was the main jet screw on the side and have replaced the fibre washer on that and that seems ok I’m gonna change the top gasket aswell so will check the float needle isn’t getting stuck and flooding the carb. The carb is a refurbished unit from rage in Holland and only couple years old so should be ok really never had no problems with it.

Cheers
 

Darren2030

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Hi fellas

Put the carburettor back on today with new gaskets top and bottom and for some bizarre reason while the engine was running I could see the gasket on top of the carburettor starting to go from grey to slowly black as petrol was trying to get out, can’t seem to fathom this out then the bottom two gaskets underneath on the adapter block started doing the same.
I can only imagine the carburettor is flooding internally some how!? I took the top off and the float was at the top with petrol roughly half in the bowl starting to p*#s me off now maybe thinking the carb is no good I have a spare Brosol which I don’t really want to use but may have no choice if I can’t sort this one out.
Any ideas to where the problem may be chaps!?

Thanks darren
 

sunnyside

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Check your float height. The gaskets in the kits are much thicker than the originals so this changes the gap between the float needle and the float, raising the height of the fuel in the float chamber which then overflows and floods the carb.

The way to check it is take the king lead off and crank the engine over for 10 seconds or so. Then take the lid off the carb, take the float out and measure the distance from the top of the carb to the top of the fuel. It should be around 18-20mm If this is incorrect, adjust the shims under the float needle accordingly
 

Darren2030

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Yeh checked float height and needle and it’s as you said mate 20mm below the top have also noticed a small leak from one of the jets on the right hand side of the carb got to be honest think it’s had it’s day!
 

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