3,200 RPM spring cut

[mhuppertz]

Anyone have any data of roughly how much the RPM goes up for each coil cut off? I know a lot of people cut two coils off, how much does that raise the defueling limit?

[unixcowboy]

I cut 2 1/2 turns and bent the remaining 1/2 turn to form the hook that's needed to connect it.
I can run up to ~ 3500 real quick then it starts defueling but the engine still pulls to 3900.

Based on my speedo with the TC locked - my tach went south about 6 mos ago and hasn't been replaced yet.

[mhuppertz]

I cut 2 1/2 turns and bent the remaining 1/2 turn to form the hook that's needed to connect it.
I can run up to ~ 3500 real quick then it starts defueling but the engine still pulls to 3900.

Based on my speedo with the TC locked - my tach went south about 6 mos ago and hasn't been replaced yet.

THanks much!

[soggy]

I cut two turns out and ran it up to 124 mph and it was still pulling, I had to let out because of egts. With 265/75/16 tires, 3.55 gear ratio and .069 OD ratio that puts me at 3230 rpms without accounting for TC slippage.

[fatty]

I cut two turns out and ran it up to 124 mph and it was still pulling, I had to let out because of egts. With 265/75/16 tires, 3.55 gear ratio and .069 OD ratio that puts me at 3230 rpms without accounting for TC slippage.

124 mph in a rattly old first gen?! You must be insane!!

[mhuppertz]

I cut two turns out and ran it up to 124 mph and it was still pulling, I had to let out because of egts. With 265/75/16 tires, 3.55 gear ratio and .069 OD ratio that puts me at 3230 rpms without accounting for TC slippage.

124 mph in a rattly old first gen?! You must be insane!!

I'm melting pistons at 120.

[soggy]

I cut two turns out and ran it up to 124 mph and it was still pulling, I had to let out because of egts. With 265/75/16 tires, 3.55 gear ratio and .069 OD ratio that puts me at 3230 rpms without accounting for TC slippage.

124 mph in a rattly old first gen?! You must be insane!!

I'm melting pistons at 120.

Yeah, me too, might have contributed to this.

[fatty]

That looks like you floated the valves to me.

[soggy]

That looks like you floated the valves to me.

How could you possibly think that by looking at this picture?

[fatty]

Well the piece of valve embedded in the top of the piston and the overall chewed up appearance are the clues that draw me to this conclusion.

[soggy]

Your argument is ridiculous, it makes no sense.

[oldestof11]

I can see what fatty is saying, thought I disagree. Look at the 3 O'Clock position. Looks kinda like a sun-dial.

[fatty]

I can see what fatty is saying, thought I disagree. Look at the 3 O'Clock position. Looks kinda like a sun-dial.

I'm almost positive that's a piece of a valve. I don't see how melting would cause the valves to break off and bounce around on top of the piston.

[diesel freak01]

broke a valve spring from high rpms possibly? or timing jumped and the piston hit the valve?

[BC.livewire]

sounds like you ware making a hi-speed run and even thow your REV spring was deefueling becouse yu ware runing past 3,200 rpm you keep going ontill one of the valve springs let go

you do know that they cummins need better valve springs for over 4,000rpm ?

even thow your pump was deefueling you still had enef fuel to get close to the 4,000 rpm limit of the stock vlave springs ---- and than your wheels hit a little bump in the road cozing them to bounce thus over REVing the motor

this is my guess --- and yes I have seen this happen in other cars and turcks ---- it all comes down to the driver pushing his motor past the limets