[Spridgets] Rejetting carbs for high altitude

JLC breton48 at live.com
Mon Mar 23 07:33:18 MST 2009


This is LBC but not Spridget content. I hope some kind soul here will answer
with the right kind of information - no one did on the Lotus 7 list I belong
to. Below is the message I sent:

Hi... I have a lotus Seven S4 Twin cam, which was jetted on a dyno at sea
level three years ago. I now live at 7400 feet, and all my driving is done
above 6000 feet. The engine is running too rich. Any suggestion for
rejetting and should I retard the timing?

Here is what I have now:

1970 Lotus Seven S4 Twin Cam, 1558 cc  (+20 thou overbore), compression
10:1. 
Twin Weber  DCOE  31 carburetors.  Chokes: 32 mm

			Cyl 1	Cyl 2	Cyl 3	Cyl 4 	Standard Twin Cam SE
specification
Emulsion Tube	F11	F11	F11	F11				F11
Main Jet		115	115	125	120
115
Idle Jet		45F8	45F8	45F8	45F8
50F8
Air corrector	155	155	155	155				150

Timing: 25 degrees at idling, 35 degrees at 4000 to 4500 rpm

JLC in the Black Forest, CO.


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