Clutching still not right!!!

[Yamanewf]

8CA'S empty, Y-G-Y, 50/42 helix, silver sec @ 60.
Machine runs like a raped ape.
8200 off the line
climbs to 8500 and holds.
Sounds good right.
Well, yesterday I got to run it on a really long lake (WOT for about 2-3 min) and around 85-90 mph the revs started to drift down untill she topped out @ 98 mph. They went from 8500 down to about 7800-8000. I thought that I was finished with the clutching. So what next? Are the 8CA's too heavy? Should I try a smaller finish angle on the helix or a different primary spring. OR could it be some other problem?

 

[Turk]

2 options
8 ab weights with maybe .8 gram in tip.
A helix with a shallower finish.

 

[Yamanewf]

Any suggestions Turk? I have a 50/40, 49/37 & 48/34. Will I have to go back to the green spring?

 

[Yamanewf]

Is there any general rule of thumb for X amount of degrees of helix angle will give you X amount of change in rpm? (Like primary weight: 1 gram of weight change equals 100 rpm)

 

[Turk]

try the 48/34 with green at 60. You may have to add tip weight & thats a good thing as that profile of weight works better that way.
There is no hard fast rule for helix changes as every manufacterer cuts em differently.

 

[Yamanewf]

Cool man. Thanks for the advice, I had figured that I would probably have to go back to the green spring due to the better clamping of the shallower finish angle. I was going to start with the 49/37 but I guess I'll jump right into the 48/34. The 50/40 is high perf eng. The 49/37 is a Bender, the 48/34 is a dalton.