Wednesday, May 14, 2008

Clampitt breaks into the 9's

Recently I wrote about Flow Area and Cam Selection In that post I mentioned Jason's dragbike heads as an example. Well, last week I finished up his heads. I was quite happy with the results, since I picked up 10 cfm from .200" lift and above on the intakes, and 20cfm on the exhausts. I was also able to get the valve to valve clearance so he could leave the 1.7:1 rockers in the engine. One drawback was that we lost a little compression ratio due to sinking the valves. Jason somehow managed to get the bike together for the weekend, and called me Monday with the results.

The bike had been running 10.13's consistantly, but even with a gear change that Jason thinks (and I aggree) hurt him, the bike is now running 9.96's. Congratulations Jason!

Of course we all know that you never want to make more than one change at a time, but in this case Jason didn't have much of a choice. He had found that the bike had been built with a misalignment between the transmission and wheel sprockets. The only sprocket that he could get on short notice to align things lowered his gear ratio. His 60 foot time increased (got slower) and the bike was practically nosing over before the finish line, yet he still lowered his e.t.'s by nearly two tenths. That's kind of exciting!

Now before you "turn up your nose" at e.t.'s in the 9.90's, keep in mind that this is only a 98" engine and Jason is a big guy (over 300 suited up to race).

Jason's dragbike last fall at the Kokesh Drags

We are all looking forward to what a gear change and a little more tuning might reveal!

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