Need cam help
Thread Starter
Teching In
Joined: Aug 2007
Posts: 9
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From: SD
Need cam help Hello, Im just starting to get into oval dirt track racing, im building my own motor this year and need some help choosing a good cam. Here are the specs of the motor:
SBC 350 bored .030 over
9.5 to compression limit
holley 500 cfm carb
441 heads
055 intake
headers
91 octane pump gas
2600lb car
would like to run at about 6500 rpms
tranny is a powergilde
its a half mile track
thanks for any help
SBC 350 bored .030 over
9.5 to compression limit
holley 500 cfm carb
441 heads
055 intake
headers
91 octane pump gas
2600lb car
would like to run at about 6500 rpms
tranny is a powergilde
its a half mile track
thanks for any help
Is this a IMCA Sport Mod? If it is I have had great success around here with a 232/220 @.050" duration, .532"/.472" lift w/1.5 ratio rockers, and a 111+3. This is for a dry slick condition track. If you can give me more info on the track condition's I can help you out better. What gear are you running in your glide, a 1.82 or a 1.76 final gear? What rear gears are you running 3.42, 3.55, or 3.73's? Are you able to run a 9" in the Northern division or are you stuck with the GM 7.5" 10 bolt?
Thread Starter
Teching In
Joined: Aug 2007
Posts: 9
Likes: 0
From: SD
Is this a IMCA Sport Mod? If it is I have had great success around here with a 232/220 @.050" duration, .532"/.472" lift w/1.5 ratio rockers, and a 111+3. This is for a dry slick condition track. If you can give me more info on the track condition's I can help you out better. What gear are you running in your glide, a 1.82 or a 1.76 final gear? What rear gears are you running 3.42, 3.55, or 3.73's? Are you able to run a 9" in the Northern division or are you stuck with the GM 7.5" 10 bolt?
I will mostly be racing at red river valley speedway in Fargo, ND. Form what I hear the track is dry most the time. The track is 1/2 mile long in the center. The class im running is wissota midwest modifed. I have a 9" with 5.67 rear gears. Final gear on the glide is 1:1.
Thread Starter
Teching In
Joined: Aug 2007
Posts: 9
Likes: 0
From: SD
The cam that I was talking about is a custom grind cam that I came up with for a very similar class here. The cam will turn about 6600-6800 rpm here at 5300 ft. elevation, I'm not sure of the elevation there, but I'm assuming that your at a lower elevation. This will allow you to rpm the cam a little bit more, so you may want to scale the cam down a touch to a 228/220 @ .050" duration, .532"/.472" lift cam, on a 109+2. Your gearing is exactly what I was thinking of for your final. In the sport mod class here they have to run the GM 7.5" 10 bolt, which makes the gearing a pain. What we have found to work well on this 7/16'" mile track is a set of 3.73's with a glide using first gear with the 1.76 ratio (1.76 x 3.73 = 6.56) or a set of 3.42's with a glide useing a 1.82 first gear (1.82 x 3.42 = 6.22). One of my sponsored drivers was useing a set of 5.83's and a 1:1 manuel tranny in Las Vegas, Nevada (1/2 mile track) and turning a consistant 6700-6800 rpm in his Stock Car.
Last edited by tonysz28; Apr 8, 2009 at 02:19 AM. Reason: spelling
Tonight was the first race of the season and the cam that I out lined here in this thread took the main event win with ease. The car owner was turning 6900 rpm with a final gear ratio of 6.22:1 on a 7/16" mile track. Please keep in mind that our actual elevation here is 5300 ft above sea level, so it is much harder to turn this kind of rpm here due to lack of air. His competition had a coniption fit after their high dollar AMS engines couldn't beat my $3500 sport mod engine. He was also able to pull 15 inch's of vacuum @ 1200 rpm after the main event was over(where they only have to pull 12).
