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MG MGB GT V8 Factory Originals Technical - Hot fuel

Hi Guys

I have just given the car its first decent run, when the car gets quite hot i can feel that the fuel is vapourising a bit, How have people kept the temperature of the fuel down?

Can i put a different seal between the carb and the inlet manifold?

I have run a copper pipe between the water pump and the heater which sits just under the carb, will the heat from this be a factor?

Thanks in Advance

Graham
GLG Lavis

I haven't heard of folks running carbs having this problem. It's more common in fuel injected set-ups since the fuel recirculates. The only solution I have seen was on Bill Guzman's orange roadster -- he had a small radiator (about 1/3 the size of an oil cooler) in line in his fuel line. You can see it on the British V8 newsletter write up about his car...

http://www.britishv8.org/MG/BillGuzman.htm

But, the UK isn't as hot as southern California so i'd be looking for other sources of heat first -- maybe that copper heater pipe... might also check to see how close your exhaust is to your fuel tank &/or fuel line. Those would be starting points for me.
x Ficalora


Quote: "Can i put a different seal between the carb and the inlet manifold?"

Certainly. You should be able to get a "phenolic" (amber-colored hard plastic) spacer from a good auto parts store or hot rod shop. They're specifically made for this purpose. The spacer will reduce hood clearance by whatever its thickness is: usually about a quarter inch. I've used one, but it was a band-aid fix, and I didn't use it for very long before finding a more elegant solution.

One thing you might want to try first is re-adjusting float height. I seem to recall that I was able to tweak my float adjustment a little off-spec one way or the other to reduce "percolation" and improve idle smoothness without other adverse effect.

Ultimately, I decided that the carb I was using was worn out. I swapped it to a newer carb and the problem totally went away.

Quote: "I have run a copper pipe between the water pump and the heater which sits just under the carb, will the heat from this be a factor?"

I doubt it... but it's easy enough to test the theory. Why not temporarily replace the copper pipe with a long length of rubber heater hose routed away from the carb? I bet it doesn't change a thing.

Quote: "a small radiator (about 1/3 the size of an oil cooler) in line in his fuel line"

Again, it's easy enough to experiment with that sort of approach... but I don't understand the logic. With tremendous respect, I have to ask: if the fuel in the fuel tank is cooler than air under the hood, then how does it make sense to run that already cool fuel through a heat exchanger that's located in such a hot location? Isn't it actually a "fuel warmer"? My intuition is that insulating the fuel line within the engine compartment makes more sense.

If you have a fuel filter in the engine compartment, you might want to consider moving it to a cooler location.

One thing that might help more is supplying the carb with nice cool air. This photo shows a slick cool-air box: http://www.britishv8.org/MG/BillGuzman/BillGuzman-17.jpg (Notice that air to the engine bypasses the radiator.)

Is your engine otherwise running hot?
Curtis

I've seen a carbie set up with a heat shield under it. Shielding from radiated heat off the top of the engine. Polished stainless with insulating material underneath. It did look impressive, however I suspect was about all that it was doing!
Possibly direct cool air onto the float bowl. Possibly attach this small bit of ducting onto the bonnet so it gets out of the way when raised.
Also insulate fuel lines as suggested.
Peter

This thread was discussed between 24/09/2006 and 26/09/2006

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