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Author Topic:   vaccuum rule
Dirt Roller

Total posts: 8
posted March 16, 2004 08:40 PM  
I race pure stock and they have a 17 inches of vaccuum @ 800 rpm. I am close to pulling is there any bolt on parts or anything I can do to get about 1-2 inches more, I am pulling fine about 1000 rpm please help..........Thanks.....

Special Ed
Dirt Full Roller

Total posts: 63
posted March 16, 2004 08:54 PM  
Hook a vacume gauge up to you carb. Set your rpms to what the rule says. You can then adjust your fuel and air mixture screws to get max vacume. Just adjust one side till you get the max vacume and then go adjust the other side. You may want to go back and forth and re-adjust a couple of times. This worked very well for us and if all you need is an inch or two then I bet this will get it for you.

Dirt Forum Champ
Total posts: 517
posted March 16, 2004 09:34 PM  
You can adjust your timing to gain some vacuum. If your running 1.6 rockers, according to my machine shop guy you can run 1.5 rockers on the exhaust to gain vacuum. I've not had to try this so I cant tell you 100% that it works but it made sense when he explained it to me.

Smith Racing Team

Dirt Forum Champ
Total posts: 516
posted March 17, 2004 12:45 AM  
Back off your valves a half turn if you can afford it, this will give you an inch or two.

Dirt Freak

Total posts: 280
posted March 23, 2004 01:04 PM  
Lock the timing advance so it's all in at idle. Spin the motor before you turn the ignition on because starting will be tougher.

Good luck,

Dirt Freak

Total posts: 431
posted March 23, 2004 01:43 PM  
SDave/ about the timing advance locking, are you refuring to welding the weights in a fixed position? What benefit will this give other than vacuum?

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