PR: Proprietary Items GP advice & suggestions

davidd

Well Known and Active Forum User
VOC Member
Its interesting that the Amal 510 delivers more fuel than any other Amal float bowl. Maurice Candy commented on this as his 500 Manx used one also. His engine produced 64 BHP. The Flash at 40 BHP got 37 MPG at Daytona, so fuel flow did not seem to be of great concern. I did check the maximum flow, which was about 3/4 of a gallon in a minute. I raced at Daytona several times and there was no cheating because my fuel tank was a little more than a gallon, which would do 10 laps while our race was 5 laps with a warm up lap.

Measuring the flow of fuel is critical. Measure the first time 1 gallon flowing out the petcock with the gas cap removed. Then measure flow with the fuel cap on. This will tell you if you have a vent slowing the fuel flow. Then do the test through the float with the cap on. If you get 8 ounces or more per minute it should be OK. If you are at the low end you should be checking to see what the obstacle is. I used a large 3/8" tap called "the Guzzler" made by Pingel. It also had a lever/cable operated remote "off" mechanism, which could be operated from the handlebar. This is required by some racing orgs. It is quite expensive, but it works very well for all different fuels.


You may be missing fuel because it is squirting out the vent hole of the float. I noticed this on the dyno. On overrun the fuel would squirt out the vent the entire time the throttle was closed due to a frequency vibration that was not noticeable to the rider. Depending on which way the vent hole points, you will not be able to notice this. The fuel shoots out and evaporates prior to discovery. Tightening the float mount a bit cured the problem.

David
 

Bill Thomas

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VOC Member
The late Dave Houghton, Sprint raced a Velo with a GP and remote float, " Road Class ",
He had that petrol coming out the top of the float chamber, Every now and again over many years,
His cure was to renew the float vale and seat, Worked every time. Cheers Bill.
 

vibrac

Well Known and Active Forum User
VOC Member
What I have learnt:
The GP2 has the float level at the bottom of the O on the carb plug it also departs from the TT and earlier GP in the pilot adjustment by metering the air and not the fuel so it is in line with road carbs ie: in for rich.
Thanks for the offer Neil we will see how it all fits together and runs on the dyno
I hopefully await any other slide size recommendations....
(which is where I came in ;) before the flow (pun) altered)
 

Phil Davies

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Non-VOC Member
Does anyone know what is the largest one made in the Gardner range, I need something at least 1 1/2" or 38 mm up to 40 mm would be ok.
Ron does carbs up to 44mm, 40 and 42 are common sizes to him, I think the 44 is only available in 'tube connect' form, but I am not 100% as none of mine are bolt on.
 

Phil Davies

Well Known and Active Forum User
Non-VOC Member
What I have learnt:
The GP2 has the float level at the bottom of the O on the carb plug it also departs from the TT and earlier GP in the pilot adjustment by metering the air and not the fuel so it is in line with road carbs ie: in for rich.
Thanks for the offer Neil we will see how it all fits together and runs on the dyno
I hopefully await any other slide size recommendations....
(which is where I came in ;) before the flow (pun) altered)
The reason the fuel is metered is specifically so high downdraft angles can be used, unlike with air metering.
What I can tell you is that there is a known 'low air flow' fuel pick up problem on GP's - precisely because of the fuel delivery method and route (and there is a fix!).
What I can also tell you is that 100% you will see a performance increase from Gardners over GPs, precisely because of better fuel metering and delivery and its consequent atomisation into the choke. One important item that lots of peeps with Gardners forget is that they do not automatically enthalpy compensate like GP's (because of the fuel delivery method), that is one reason why they are so easily adjustable - because they have to be each time!
What I also also know is that Ron's float chambers do not froth, unlike the amal's (despite what amal used to say to the contrary).
 

greg brillus

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VOC Member
Great Info Phil, can you advise as to the approximate cost of the Gardner carb's and the float bowls to suit. this will be to run on a 665 cc Comet race engine. Cheers.......Greg.
 

vibrac

Well Known and Active Forum User
VOC Member
The reason the fuel is metered is specifically so high downdraft angles can be used, unlike with air metering.
What I can tell you is that there is a known 'low air flow' fuel pick up problem on GP's - precisely because of the fuel delivery method and route (and there is a fix!).
Phil as I have MK2. GP and a steep down draft I would be most interested in the 'fix' for the front carb
 

highbury731

Well Known and Active Forum User
VOC Member
Does anyone know what is the largest one made in the Gardner range, I need something at least 1 1/2" or 38 mm up to 40 mm would be ok.
I read somewhere that Gardner would make his carburetors any size. Someone asked for a 2 1/4" carb to fit to a Harley, so he made it
Paul
 
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