Clutch difference between Flathead and Clone

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.
 

alvin l nunley

Site Supporter
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.
 

racing promotor

Moderator
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.
You might be correct Al but I think he's asking about gearing comparison.
 
Your asking how much bigger front driver ?
What was your flathead gearing ?
Do you know track size ?
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.
 

racing promotor

Moderator
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.
Most always 1 bigger your thinking correct should put you real close to start provided your close on tires as well.
 

OVALTECH1

Site Supporter
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.
 

alvin l nunley

Site Supporter
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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