4k gsk nowhere near 4000rpm
#1
4k gsk nowhere near 4000rpm
Hello, i recently installed pacbrake 4k gsk in a 96 cummins that i swapped into a 97 gmc dually and i can maybe get 2800rpm. That is even with the springs tightened down a bit more than spec. Engine idle is about 150rpm higher but still starts as good as before. I have a steady 35psi fuel pressure at wot from an electric lift. Any ideas as to why rpm is so low? i measured timing the other day and it was approx 11deg by the measurement charts i had found, from what im told stock is 12, would this have an effect on higher rpm to this extent? any advice would be great, thanks!
#2
I'd say your doing pretty good if you can hit 2800 at 11°, I've seen trucks that will barely run at 10°. I'm not saying that's your problem, but I suggest you bump it to at least 15-17 and see what happens. Do you have stronger valve springs? Because you'll float your valves if you spin it anywhere near 4K with stock ones.
#3