jetting for altitude

[scott]

It looks like I may be moving to Colorado in the next few months. My engine has dual dellortos and produces 148 hp @ 6500 rpm. Does anyone know what jetting I'll need at around 6000 ft? If anyone has raced at Aspen or Centennial I'd love to know their jetting. Scott

[miked]

Scott,

If you dig back and search I am sure there was massive discusion here by Keith (no longer posts) about this.

He was either called type 26 or 36 but posted loads on carbs. Worth a search.

Mike

[Foxie]

Scott,

I've had the +2 up over 9,000 feet in the Alps and the engine never faltered. It's on Weber carbs. Of course the jetting might not be optimum at these altitudes, but I never stayed long enough to carry out tests !

Sean Murray

[gordonlund]

My +2 was approx one mile high in the Pyrenees France/Spanish border in May last and never missed a beat. 146 bhp sounds a lot for a stock twink whether it be big valve or otherwise?? Fuel injection and full engine management to road spec could get that sort of output. Hairy race cams and special tuning mods can get a lot more I know but at what expence reliability and cost. If you are looking for a marginal correction at flying altitudes then I suggest a Supermarine Spitfire!!

Happy New Year to all

Gordon

[Ross Robbins]

I ran my weber carbed engine with 5-10 smaller main jets and/or 10 bigger air correctors than I used at sea level, and it ran fine. The best thing I can suggest is to call me or one ot the other LOCO's when you get here and we will put you in touch with Walt and Chip Hane who have a chassis dyno and with a variety of jets can tune it perfectly as they are at about 6,000 feet elevation. Once you are set for that altitude, my experience is that you will run fine aver 12,000 foot passes even though it may not be optimum.

Ross Robbins
PS LOCO is Lotus Colorado...our local and very active club that put on LOG 27 in Aspen/