Lotus Elan

Weber Jetting For Altitude

PostPost by: type26owner » Fri Aug 26, 2005 4:28 pm

Gee, I wonder if the problem getting the twinkcam to idle at a steady rate is because the engine is overcooled at idle from the E10. Bet removing all the water from the cooling system and running just neat anti-freeze would reduce the thermal loses so it would achieve thermal equilibrium quicker and idle more smoothly. Also need to get the oil up to the temperature of the coolant so the piston runs a tad bit warmer at idle too. As the combustion cylinder quickly cools off less of this summer fuel is vaporating and getting burnt therefore changing the mixture. Less heat means less cylinder pressure. I need to reinstall my AFM and look for this effect. No wonder my brother does not have that bad a problem with the cast iron head on his Kent crossflow engine.
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PostPost by: rgh0 » Tue Aug 30, 2005 11:23 am


The carbs on my roadplus 2 on normal premium unlead gasoline in Australia remain around ambient temperture after normal road use. On a 25 degree C day they will be round 25 degree C.

It appears that cooling from the ambient air flowing though and around the carbs plus cooling from vaporisation of fuel in the atomisation circuits and carb barrels roughly counteracts heating from surrounding engine components

On hot days - say 40 C the carbs get hotter but not up to a full ambient 40 C.

On my S1 Esprit the carbs run much hotter than the plus 2 presumably due to the higher heat soak rate in the mid engine bay with lower cooling air flow around the carbs and more heating from surround engine components.

Both cars use Delortos not Webers but the designs are similar so heat effects on the carbs hould be the same.

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