Engine/Transmission (1994 - 1998) pacbrake butterfly hole sizes

[qkoop]

I have a 94, stick and I am installing a pacbrake from an automatic. I've read the info on the hole sizes on another thread and was wondering if i could keep my stock valve springs and play with the hole sizes in the butterfly since I never would use the pacbrake over 2500 RPM. I know I am supposed to have a 31/64ths hole in the butterfly and also the champferd hole open, but I was thinking of maybe drilling a 3/8ths hole instead to keep the pressure up. Any ideas or suggestions? I guess I could also put a pressure gauge on, but I thought someone could save me the work and give me their experiences.



Thanks

 

[bighammer]

I think you can use it with nothing in the chamfered hole without the springs. If you get the heavy springs, you put a bolt in there and plug it up. I wouldn't change the holes. The valve springs are not that hard to change, (if you can adjust the valve lash, you can upgrade the springs) and it will make it brake more effectively.

 

[qkoop]

ya i think i had better not screw with it. I really don,t want to float a valve into the piston. Do you know the safe max braking rpm ?

 

[Doubleclutch]

Sounds familiar... I bought a Pacbrake for an auto- by mistake. Called Pacbrake for advice. Since I already had the 60# springs installed, they told me to drill a 1/2" hole in the disc, and call it good. Those words on the box "will cause severe engine damage" were taken to heart and prompted my calls. I would suggest you do the same! Good luck,

Greg

 

[WDaniels]

qkoop,

The pac break is designed to work at a higher rpm than say the BD or Jake brake butterfly valves. Those two breaks work best at mid rpm's for breaking. The Pac really shines at about 2500 to 3000 rpm. I've tried all 3 and for heavy hauling the pac with the upgraded springs and the little bolt to plug the butterfly hole is the one I like the best. Just my 2 cents worth.

WD

 

[RHARVEY]

I have been down this road before. . The 24v brake that I installed on my truck needed a 31/64" hole and a 1/4" hole in the butterfly. And the reason that I know is because I called pacBrake and this is the sizes that they said to drill. If you have the 60lb springs... dont drill the 1/4 hole... Or when you install the 60 lb springs... then you plug up the 1/4 hole...



Rick