Reply to "Monster 2786 Type 4 build"

edsnovaBaltimore - BCW 52 MG TD Supporting Member

Aircooled says this cam is .435 lift with 1.3 rockers. I think that is mild, as is the 252 degrees duration at .05. It also says the powerband goes to 6000 rpm, which ... how?

By way of comparison, the Engle W125 in my little 1914 has an advertised lift of .460 with 1.1 rockers and 262 degrees duration at .05 lift. The dyno charts on these engines, as built by Raby with 8.5-1 compression, dual springs & Weber 44s, show peak torque (circa 125 ft-lbs) at 4000 and peak HP (122-ish) at 5500. Raby revved them to 6k on the stand, losing 2-3 hp off peak, before shutting down.

Judging by chatter on the forums, lots of Type 4 players love the Webcam 86A, and I would not challenge the judgment of a real, experienced engine builder, but I am curious to learn how such a small cam would be deemed optimal for such a large engine, as built for such a light vehicle as the Puma.

9/11/206:27 AM

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