Up Hill Power Loss

oldbloke

oldbloke

Active Member
My '70 NADA 3500S runs very well on extended runs on fairly flat roads. Will cruise at 80-85 MPH if desired, but a long hill gives way to coughing/sputtering and blowing carbon(?). Power comes back going down hill...! Compression ratio is good at 135 approx, but required a little mystery oil down the plug holes. Using premium fuel and and seem to be getting 18-20+ MPG. No overheating post R&R of radiator and waterpump. Thoughts?
 
harveyp6 said:
Fuel starvation?
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+1. Talking to a previous owner of my car that was his number one observation of his time with my car back in the 80's hill climbing and fuel starvation or vaporization when climbing hills.

Graeme
 
The fuel consumption figures that you sited possibly suggest that the engine is running too rich with reasonably light throttle settings, but too lean when you require more.

Do you know what needles you're running and when were the carburettors last overhauled?

Ron.
 
Yeah, club member following me said it appeared pretty dark and his opinion was carbon. Pretty tired high mileage engine so blow by from bad rings is a possibility. As stated, a little oil down the plug holes seems to help.
 
I imagine his 18/20 mpg is per US gallon, which equates to about 22-25 mpg which i would say was good for a 3500, and certainly does not suggest overrichness to me
 
I would not say its carb problem---I think its the pump failing-easily forgotten that the diaphragms split---not a problem to rebuild or better still go electric pump instead
 
symes wrote,...
I think its the pump failing-easily forgotten that the diaphragms split---not a problem to rebuild or better still go electric pump instead
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The NADA 3500S was not fitted with a mechanical fuel pump. An electric beneath the tank was the standard arrangement.

Ron.
 
In that case, start by cleaning out the fuel lines between tank and engine to make sure it's free of
obstructions and crud. Then, I'd drop the sender out and check the bottom of the tank for crud
blocking the pick-ups before going on to the pump and having a look at it's condition. While you're
at it, fit a filter in the line between tank and pump to stop crud getting into the pump.
 
unstable load said:
In that case, start by cleaning out the fuel lines between tank and engine to make sure it's free of
obstructions and crud. Then, I'd drop the sender out and check the bottom of the tank for crud
blocking the pick-ups before going on to the pump and having a look at it's condition. While you're
at it, fit a filter in the line between tank and pump to stop crud getting into the pump.
Click to expand...
+1
 
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