Home made 4-cam hemi fire up #2

This fire up was to test the clutch. The idea is that you set the clutch to slip at a certain RPM, not only so it will not spin the tires at the hit, but so you can control the car to get it into reverse after the burn out and stage the car. You want to have just enough drag to where if your hand is off the brake the car will creep, but not so much that the brakes won't hold the car. You also want to be able to bring the RPMs to the point where the motor runs clean so when you hit it the motor picks right up instantly rather than having to catch up with the volume of fuel you're dumping in there; or worse, gag and die on the line because you're dumping more fuel in than it's ready to handle.

Tommy was told to set it up so it will launch at 3000 rpm, so that's what I was zinging it up to in this video. It's kinda eerie. The car starts shaking and really changing tune. You can see Tommy come over and depress the clutch pedal, lock it, and then try to get the clutch to slip by using the handbrake... which if you notice, the tires aren't slowing down and smoke is just pouring out of the brakes.

We also found on this run that the tach in the car is off by 100%. I was twisting it at 3000 according to the temporary tach in the seat, and the one on the control panel was bouncing around 6000. No wonder we hurt the motor last time out at the track. Tommy launched it at what he thought was 2500 RPM and it was obviously more like 1250, so that explains why the motor hydraulicked and hurt the bottom end.

Back to the drawing board. We made some adjustments to the clutch and tried it again with much better results. but a 3000 launch rpm just seems awfully high.

He ended up making a few phone calls and the Skuza's told him to set it up to launch at 2200 RPM. Much better on my nerves at least! I can't imagine having to do this on a 90% load of nitro... I'd better have my life insurance paid up. So we'll try it again tomorrow.

BTW- the truck tires on the back are just to be able to get it to fit into the trailer, obviously when we're at the track we have full size slicks on it.

Category:

Autos & Vehicles

Tags:

• hemi
• dragster
• top
• fuel