Box Stock

Clutch difference between Flathead and Clone

J

Joemac3003

Member
I have some notes for a track we use to run flat heads on and trying for figure out how much I need to go up on the clutch for a clone.
 
I think most would agree, the clutch stall RPM, on any engine, on any track should be set to the engines peak torque RPM.
Something you might try; place an analog bathroom scale between the front of your kart and a strong wall. The clutch stall RPM that produces the highest readings would be best.
 
alvin l nunley said:
I think most would agree, the clutch stall RPM, on any engine, on any track should be set to the engines peak torque RPM.
Something you might try; place an analog bathroom scale between the front of your kart and a strong wall. The clutch stall RPM that produces the highest readings would be best.
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You might be correct Al but I think he's asking about gearing comparison.
 
racing promotor said:
Your asking how much bigger front driver ?
What was your flathead gearing ?
Do you know track size ?
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Yea we ran a 14-63 on flathead and I was thinking a 15-63 for clone. I may have to change the clutch when I get there but I’m trying to get a starting point. Haven’t ran there in 20 years and just got back in to Karting in January and none of my gear notes have been helpful.
 
Joemac3003 said:
Yea we ran a 14-63 on flathead and I was thinking a 15-63 for clone. I may have to change the clutch when I get there but I’m trying to get a starting point. Haven’t ran there in 20 years and just got back in to Karting in January and none of my gear notes have been helpful.
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Most always 1 bigger your thinking correct should put you real close to start provided your close on tires as well.
 
Clone is almost always 1-2 bigger on front driver... we run 11-12 on our flatties with a 63-65 rear gear. And 12-14 on our clones with 62-64 rear gear. Big 1/8 mile non momentum track with little bite.
 
Be aware that when you change from an 11 to a 12 driver, that's the equivalent to changing the axle by 6 teeth.
11/62 = 5.64
12/68 = 5.67
 
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