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SU carbs will not sustain Heavy load

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On 12/8/2018 at 12:00 PM, 240dkw said:

I was just reading a TSB for the 1973 carb mods and the fuel free flow test with both the elec and mech pumps is 3 pints/min or 22.5 us gal/hr at 1000 rpm's so I do not think your pump is weak. If you do not find a "smoking gun" with a fuel problem, you should try changing out the capacitor on the dizzy. As they get old they can start to fail at higher voltage and create a problem where the rpm's go flat at WOT looking like a fuel starvation issue. 

The thing is, not all pumps are created equal. Just because the factory pump does X a free flow does not mean it will do the same as another pump under load.
Example: say the factory pump does 22.5 free and 10 at 5 psi. and another pump does 30 free but only 3 at 5 psi, it still won't be good enough.


23 hours ago, siteunseen said:

I haven't read all the post but I found my low float level after running up a very long and steep mountain.  About half way up it started running on the back carb, half power.  I cut the wheel and rolled it perpendicular with the road, cranked on it a few times and it cleared right up.  Went about another mile, same thing.  I went back down and it ran great the rest of the way home.

After a week I had the floats set right and it runs fantastic now all the way to 6,000-6,5000 rpm.

Sorry if already told this but it's the best thing I've done to my SUs.





Yeah, I toyed with float levels a bit, even made them higher than stock and still no benefit. I like your off vehicle float adjustment.


Edited by MY1PATH
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