Slow Motion Tire Shake

Good questions

Answers to most:

 

same issues

i'm having shake probs also. thanks everyone for sharing so others can read.

 

Traditionally a roots car is a "high speed" car. My background in converters and small blocks is pretty good. That being said, I wouldn't turn anything on before 2 seconds. The small block espesically likes fuel at the hit, if the high speed is coming on that early then I'd say that's 99.9% of the problem. The next question(s)

Pump Size?
Flow (bare pump) at 8000RPM? (should have come with sheet when it was flowed)
Nozzle Area?
Nozzles in ports?
Nozzles in blower?
PSI on port/idle poppets?
Pump loop?
Barrel valve leakage %?

From when we talked earlier, you can run more timing and turn the high speed on at 2.0, if your fuel system is close, a 50 would be good in the high speed. Give me a call and we can sort of go through your setup over the phone, the high speed being on that early changes everything.

Brandon
217-840-1500

 

110 pump
Sheet has 4000 as 941 gpm
Nozzles around .0271 with hat at .0190 and ports at .0081
Not exactly sure of the port but idle poppet is 6#
no loop except pump saver
BV is at 82%
Main is 90
Head temp at stage is 125 - 135

Ran this week without the hi speed, no help. The egt's do rise fast and was thinking we were not fat enough at the hit and was going to fatten the barrel valve more but what the heck does that do?? So it kills the oil and there is a little more fuel there for a split second. But as soon as the throttle is wide open, the bv is wide open and what has fattening it gotten you??? If you bleed more air in to adjust the idle whether by opening the throttle blades or bleeding in under the blades, aren't you back to the same air /fuel mixture?? When staged and you bring the idle up, haven't you killed the bv setting? Confused!

 

So no one can answer the barrel valve questions??????

 

You can add a "hi speed"....and use it as a lauch richening. Fatten up the main for a rich launch..then have the "hi-speed" open about 100' into the run. You will need to know the pump pressure at that time of the run in order to set the poppet. So if the car runs well with the main you have now, calculate the jet area now. Then what ever you make the main fatter at the start, take out with the hi-speed. I hope I explained this well enough......

 

We did this Friday night. Went from 90 main to a 50, high speed 50 to 90, bumped the hi speed pressure.....still shook.

 

Your nozzle area seems way off....and the BV as well. I'll look and see what we had with our SB, call me tomorrow around 2 or 3 in the afternoon.

Brandon Booher
NHRA TAD #35