The advantage that these old engines have over newer engines, and particularly small air-cooled two strokes, is the fact that they were designed and built before the proliferation of exotic polymers and fancy mixture management. WHEN a system stays clean and dry, and the fuel is not stored or left to sit long, it works out okay, but machines, especially antiques, are not generally under constant use. The two greatest issues with ethanol in larger motor fuel engines, are it's hygroscopy, and reactivity to various materials in components of the fueling system, AND those of the environment that find their way in. So - if you have a hard-starting or no-starting low CR engine from the early days, Lower the Octane. It even stopped a majority of its smoking - tho' now it does smell a bit like a lantern! I had him dip the tank and guestimate how much fuel he had, then he added a jug of Kerosene that had been sitting around to get ~70-75Oct, had him drain the carb and let fuel run a bit to get the un-mized fuel out of the line. Kerosene ~ 16 Oct, or Diesel ~19-22 Oct and use a mix calculator. Search 'how to lower octane' for some lengthy and mostly unproductive web-time! We al know how to raise it, and there are plenty of additives, yadayada. It was astoundingly low: 1935-1950 engines ran said 6-ish CR and Octane was 70-80 So - in 1947 Pump Gas was NOT the 89/92 R+M/2 of today. Compression on his is less than stock due to age, but around 6.6:1 if it were all good. Told him I'd get back to him.įWIW timing on the 8N is straight up.

Fortunately he uses pump premium with an additive (94/96 Oct calc'd). had spark, had fuel, the plugs weren't fuel-dry, and so-on.Īfter a bit I asked when the last gas was purchased, and as met with 'oh, I just tossed the leftover race-gas in it after the last race'. He called and said it had stopped starting and wouldn't go no matter what he did. He's not good with carb setting - so I get to tweak it for summer/winter, stale gas etc. Just an observation and tale of 'I fixed it via telephone' message.Ī friend has an early Ford 8N (1947) and I've had occasion to 'tune it up' for him when the weather changes.

8n fuel line routing to carburetor