lean fuel mixture

Ivor · Post by **Ivor** » Wed Jun 02, 04 9:25 am

Yep. Lotus Super Seven 1500 Cosworth...changed the jets in the 40 DCOEs and it never happened again.

I agree with Wiggy, that's one fine automobile...tell us more!

Dave-R · Post by **Dave-R** » Wed Jun 02, 04 10:19 am

Too lean makes the engine hotter and can lead to pre-ignition. It also overheats the exhaust valve and headers. It may not actually boil the water unless the cooling system is marginal anyway.

Too rich can also cause localised overheating in the exhaust valve and manifold/headers if it is very rich indeed. This is due to unburnt fuel burning as it goes past the exhaust valve and into the exhaust system.

db · Post by db » Thu Jun 03, 04 1:43 pm

I've had lean-burn overheating caused by inlet manifold leaking, took a l o n g time to suss that one! It was only misfiring under load so tweaking mixture/ timing had no effect til i drove it uphill, then it wheezed to a halt. Finally struggled an spluttered to a garage, they diagnosed it in about 3 minutes