Float needle seat.

In the Amal carburretor rebuild information, it states referring to the float seat needle measurement,

The seating depth was further reduced to 0.574” in May 1986 and has remained as that ever since.

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I am not sure where this measurement is taken from and to? My best guess is from the top edge of the float chamber to the top edge of the float needle seat insert. Can anybody confirm this?

Reggie said:

I am not sure where this measurement is taken from and to? My best guess is from the top edge of the float chamber to the top edge of the float needle seat insert. Can anybody confirm this?

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The "needle seat" as I understand it, is where the tip of the float needle rests, and measuring the distance between that point and the float chamber gasket face of a spare bowl gives a dimension very close to the Amal measurement. The distance between the top edge of the brass needle insert and the gasket face is considerably less than 0.574".

Thanks Les, that makes sense. No wonder I couldn't fathom it. I never thought of the where the tip of the needle sits as being an accurate datum point But thinking about it, why not :?:

I highly recommend the Amal "Stay-up" floats, they are fully adjustable and made from a material that is immune to alcohol degradation; using these floats and setting them correctly zeros out all other almost-impossible-to-do adjustments.

RS

I'd be interested to know how "impervious" to alcohol they really are after a few years! Heck, Quadrajet floats quit floating after around 2 years and they didn't even have to deal with alcohol.

Mike996

Here is a direct quote from Amal's web-site:

"The new adjustable height StayUp float is resistant to modern ethanol based fuels and has a military spec closed cell construction making it puncture proof. The ability to adjust the float arm allows for quick and easy minor alterations to float levels where required".

The material specified was used by the S.U Carburetter Company for military installations in the 1980s, where a guaranteed fail safe operation was critical. Due to the close link between S.U and AMAL today (both owned by Burlen Fuel Systems Ltd), the secret behind the material has been released and upgraded for the manufacture of this float, making it virtually unsinkable"

I suppose they could be lying to us, but I'd say that they have too much to lose by doing so...

RS

Like the High Quality new carbs with optional non-finished holes and swarf left for recovery and sale to the scrapman !!!

I have one of these floats but plan to use it for setting up purposes only, once I have the carb dialed in it will be taken out and the old one put back in with the seat set to get the same fuel level.

kommando said:

Like the High Quality new carbs with optional non-finished holes and swarf left for recovery and sale to the scrapman !!!

I have one of these floats but plan to use it for setting up purposes only, once I have the carb dialed in it will be taken out and the old one put back in with the seat set to get the same fuel level.

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These floats have metal tangs so they can be bent to adjust the float height rather than heating up the float bowl to lower and raise the needle seat. Do not expect the setting from one to the other to be the same like an injected molded item might be. Once the float is in the carb and adjusted, it should be considered proprietary to that carb.
Again, do not expect the new float to be anything like the old one. If you swap the new float to the old after setting it up, all settings will be lost, unless you are very very very very very very very very lucky.

Frankly, I haven't seen any problem at all with adjusting the standard Amal float seat for setting the float. The biggest problem - which doesn't change with the new float - is deciding on which of the various advocated float settings you decide to use!

mike966 wrote;

The biggest problem - which doesn't change with the new float - is deciding on which of the various advocated float settings you decide to use!

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http://www.amalcarb.co.uk/TechnicalDetail.aspx?id=11

From Burlen/Amal website under "1966 to 1972"

The correct fuel level for all Mark 1 Concentric carburetters is 0.21” plus or minus 0.040” below the top edge of the float bowl.

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From Burlen/Amal website, under "1972 to present"

. The seating depth was further reduced to 0.574” in May 1986 and has remained as that ever since. In this position the fuel level is correct when the top surface of the float is parallel with and just above the top of the float chamber when the valve is closed.

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I rang up for clarification about this, and the technical expert at Amal told me that yes on the "later carbs "(I assume 1972 onwards), the float should sit about parallel with the float bowl as in the photos. The 0.80"setting was for earlier Amal concentrics which used to run a bit rich, and since then the settings have been changed (presumably means the float needle seat setting and the adjustment to the slots for the float spindle) so make of that what you will?