What, technically, causes "loping" in a motor with a cam installed?
Thread Starter
Staging Lane
Joined: Dec 2011
Posts: 56
Likes: 2
From: Berlin, CT
What, technically, causes "loping" in a motor with a cam installed? I understand the vague generality of smaller LSAs increasing the odds that a motor will lope, and also that loping is a function of vaccuum; my question is: what aspects of cam timing create low vaccuum (which in turn creates loping)? Too much overlap?
If so, then it would follow that smaller duration profiles (say, 218 - 224) could be built into a cam with a smaller LSA and be less likely to produce a lope, yes?
Thanks, Jon
If so, then it would follow that smaller duration profiles (say, 218 - 224) could be built into a cam with a smaller LSA and be less likely to produce a lope, yes?
Thanks, Jon
TECH Apprentice
Joined: Oct 2007
Posts: 301
Likes: 20
The "lope" or "chop" is actually caused by misfiring. Wide overlap cams don't do a good job of clearing the burned fuel/air mixture out of the cylinder at low rpm's, so your air/fuel mix is polluted, causing a misfire. Keep in mind that the intake and exhaust valves are open at the same time, the burned fuel/air mix can actually be pushed/drawn back into the intake, which causes the same misfire. Once the engine gets the rpm's up, there's no polution of the fuel/air mix, so it fires as it should again.
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dont forget also, that the sound is created when the valve is opened and closed REALLY quickly. it will be about as noisy when you push compressed air through a motor to run it
