HS8 float level - engine flooded!

R

roverrocket

Member
Hi all. I recently switched cards with a spare set I have and on start up billows of smoke pumped out and petrol started to come out number 1 spark plug hole (which wasn't tightened properly, thankfully). I took the float chamber lid off the old set of carbs and the problem persists. Petrol has now mixed with the engine oil and I guess this diluted mixture allows it to travel into the combustion chambers - the smoke has got worse. Couple of things: why are the floats different in the front and back chambers? in the absence of 7/16 bar can I simply play with the float lever until it's acceptable? If I manually pump fuel and observe the jets with the filter off I can adjust the float level until no fuel is pumped through the jets - everyone agree? Really hoping I haven't done any serious damage here
 
The float level is quite critical and I don't think trial and error would work. Use a 7/16 drill bit to set the level and check that the floats actually float and that the needle valves are clean.
 
I would recommend that you consider changing the floats to ethanol compatible floats. Probably only one float was changed when it sank, and became full of fuel. It was then replaced. I would at least replace one that is made of metal. Here is a link to the float you need. What are you floats made of?

http://sucarb.co.uk/float-chambers-spar ... float.html

Have you checked the diaphragm of your petrol pump. The diaphragm can leak fuel into the oil if it develops a hole.

James.
 
The floats appear fine and I have changed them for identical brass ones which float fine. If a float valve is stuck open is petrol in the oil a usual symptom?
 
We ran a technical article in Driving Force a few issues ago covering coping with modern unleaded fuels with a P6. Our research and collective experience to date is suggesting that the only vulnerabilities in all P6 fuel systems is the O-ring in the reserve tap (nitrile ethanol resistant examples now available from P6 suppliers for pennies), and the diaphragm in the AED device on NADA models, which were never known to be .

There shouldn't be any concerns over the floats, especially brass items as found in the HD and HS series carbs. Of greater concern is how to compensate for the different chemical make-up of E10. Standard unleaded is of a different make-up to original 4 or 5 star anyway, so some degree of compensation in the ignition advance and carb needle profiles is already necessary to achieve factory performance. But for those interested in extracting the last few percent out of their engine's performance, an additional amount of adjustment to these factors may be necessary to compensate for the increased volatility of the forthcoming E10 fuel.

Michael
 
redrover said:
We ran a technical article in Driving Force a few issues ago covering coping with modern unleaded fuels with a P6. Our research and collective experience to date is suggesting that the only vulnerabilities in all P6 fuel systems is the O-ring in the reserve tap (nitrile ethanol resistant examples now available from P6 suppliers for pennies), and the diaphragm in the AED device on NADA models, which were never known to be .

There shouldn't be any concerns over the floats, especially brass items as found in the HD and HS series carbs.

Michael
Click to expand...

Thats interesting that you found that. I seemed to have been going through one float per year, until I changed to plastic floats. I know that at least one of the floats I purchased I paid a premium for, so it would be one made in the UK, not China. Another float was from a supplier in New York city. I have been very happy with the plastic ones. I am also now only filling with ethanol free petrol. It was not a nice sound when you hear petrol overflowing, and landing on the exhaust manifold. Do you have ethanol in the fuel in the UK?
 
We do have ethanol in petrol in the UK, but currently only 5% although it is likely to increase to 10%. Ethanol, if it is allowed to remain in the fuel system, will oxidise to acid and will attack brass. Best bet is to use ethanol resistant plastic floats and not to leave a lot of fuel in the tank if you don't use the car very much or use a suitable additive.
 
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