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Old 08-29-2010, 12:06 PM   #1
Truckracer
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Video from this weekend racing

Ratpwrd72 driving in no electronics at Ardmore Raceway this weekend, went to the semi's.

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Old 08-29-2010, 12:18 PM   #2
RatPwrd72
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Re: Video from this weekend racing

Ha, beat me to it, I was gonna post the video to share. Made some 1/4 mile runs Friday night with this setup. After taking the Flying Toilet/Methanol off the engine and going back to a mech. secondaries 950 on gas, I hadn't run it past 1/8th mile. Went 10.59 @ 126. Yesterday was a bracket race, so 1/8th mile only. Ran a whole string of 6.77's at 103, then ran 6.75 when the air got better. Made it 5 rounds and got my first ever check from the racetrack. Had a good time and didn't turn a wrench all weekend. Anybody want to donate some paint?
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1972 Chevy Cheyenne Super- Pump gas 496,TH-400, TCI Stall, 3.73's,Ochre & White two-tone w/Olive
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1967 Chevy Short Step Drag Truck-Iron Headed 468 Making Memories

My momma took me off the bottle years ago.....
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Old 08-30-2010, 12:56 PM   #3
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Re: Video from this weekend racing

Nice times.. Couple questions for you..

Is your front end strapped/chained down? Watching your launches it looks like you get very little movement in it. I also noticed it oscilates a bit front to back right after the launch (Maybe even as far out as the 60' mark)..

What does your front and rear suspension consist of? Factory or modified? (Guessing M2 front with the front width).

Kind of 60's were you cutting?
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------Motor---------------Bottle
60'---1.53---------------1.41
1/8---6.58 @ 105.92----5.87 @ 118.41
1/4---10.38 @ 126.97----9.24 @ 142.49
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Old 08-30-2010, 05:07 PM   #4
RatPwrd72
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Re: Video from this weekend racing

Quote:
Originally Posted by Super73 View Post
Nice times.. Couple questions for you..

Is your front end strapped/chained down? Watching your launches it looks like you get very little movement in it. I also noticed it oscilates a bit front to back right after the launch (Maybe even as far out as the 60' mark)..

What does your front and rear suspension consist of? Factory or modified? (Guessing M2 front with the front width).

Kind of 60's were you cutting?
Front end is a Jegster front circa 1983. It has a rack & pinion with Vega spindles/shocks and travel limiters. The rear is stock trailing arms and springs, stock replacement shocks.

The "hop" as we've been calling it used to be a lot less and then became even worse. Now we're getting better. The last motor combo with mechanical fuel injection hit the tires harder and didn't allow as much hop. It would hike the left front and 60'd in the mid 1.40's. We've since switched to a gas carb and a less radical cam which brought some hop back to the launch. I talked with my Goodyear distributor where I bought the tires new and learned a few things in the process. I have a stiff sidewall slick that requires more air than I was running. Usually I ran them at 8 lbs, they said to start at 15...

Also, they recommended rotating the tires side to side every 10-15 passes, this was a new one on me. So, in these videos I've got 13 psi in the freshly rotated slicks with less starting line RPM than usual to allow the converter to flash a little harder. 60's in this video are all 1.54's and 1.55's.

Now, we're considering a change to the distributor to lock the timing all in. At the rpm I want to leave at, the mechanical advance is was low in the curve. I bet there is a few HP to be found down low in doing this.
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1972 Chevy Cheyenne Super- Pump gas 496,TH-400, TCI Stall, 3.73's,Ochre & White two-tone w/Olive
Interior

1967 Chevy Short Step Drag Truck-Iron Headed 468 Making Memories

My momma took me off the bottle years ago.....
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Old 08-30-2010, 05:46 PM   #5
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Re: Video from this weekend racing

Thanks for the info on you truck.. Just curious if some of the oscilation you are seeing in the suspension could be due to spring rates. Even though they may not be the same rate fron to back, they could be "harmonizing" with each other due to the leverage on the springs ect. Dave Morgan who worked for Alston for 20+ years doing chasis adjustments and set up talks about oscilation in the 5 dvd set I have of his, how two different spring rates could do this.


If this means anything, I had 19* of timing in my truck in march when I went to the track. It cut a 1.67 60'

I know from playing with timing on the dyno, reducing it from 29* to 19* looses aprox 95-105rwhp..

Put the 29* timing in it and cut a 1.59x...
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------Motor---------------Bottle
60'---1.53---------------1.41
1/8---6.58 @ 105.92----5.87 @ 118.41
1/4---10.38 @ 126.97----9.24 @ 142.49
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