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Author Topic:   stagger rocker arms
02 racin
Dirt Newbie

Total posts: 3
posted December 18, 2005 08:58 AM  
i have double hump heads and i'm running 1.5 rockers somebody told me to put 1.6 on int. and 1.5 on ext. to help what will this do thanks

James Ott
Dirt Maniac

Total posts: 175
posted December 18, 2005 09:54 AM  
gives you more lift on the intake plus more duration. Will fill the cylinder better

Dirt Freak

Total posts: 438
posted December 19, 2005 07:43 AM  
Not more duration, that's ground in the cam and not adjustable, just more area under the lift curve.

I'd go with 1.6 on both valves though. Those exhaust port's aren't very good so if you only have a half set, try putting them on the exhaust instead.

If your port's are untouched, your likley already at max flow for the lift so going higher won't net you anything.

Dirt Newbie

Total posts: 1
posted December 19, 2005 04:30 PM  
James is correct on the increase in duration, typically around 2-5 degrees, depending alot upon lobe duration and rocker ratio. However, probably the bigger of the net effects will be the area under the curve as lizard said, especially in your case.

Dirt Full Roller

Total posts: 28
posted December 19, 2005 07:32 PM  
I pretty much always run more rocker ratio on the intakes. You want to get the intake open fast. Plus you want gentler valve action on the exhaust valves due to the heat they're subjected to, they're prone to popping valve heads off. Craftsman Truck/Busch stuff is usally 1.85 intake 1.75 exhaust. We put new valve springs on every race. Dirt stuffs milder 1.6 intake 1.5 exhaust because we don't change valve springs as often.

Dirt Freak

Total posts: 438
posted December 20, 2005 07:40 AM  
The engine will ACT like more duration becuase of of the faster valve action but NO increase of duration will actaully happen. Don't believe me, graph it out.

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