squirlchasr919

My 96 has a 4k GSK in it and it still won't come above 2900-3000rpm. I guess it would if I manually held it in a lower gear but I figured it would still do it on it's own. I can even build boost on the line and let it go and it will still hold steady at 3k and go through the gears spinning through first and second.
The idle is fine and the throttle isn't overly sensitive giving a clue to the governor springs being too loose or tight. Could the tranny be the culprit, it just shifts into the next gear when it hits 3k, rather than hold the gear up into the higher rpms?

ratsun

Sounds like trans adjustment time.
Try holding it in gear and see if it goes up, it should

Racer9

Is it still pulling at 3k, or starting to defuel? Boost dropping off, or still building? Like Ratsun said, manually shift it and see what happens.

squirlchasr919

It's still fueling like there's no tommorow. Boost doesn't begin to drop at all. In fact it is still rising, 45psi is probably doing more harm than good to that stock turbo. Time to quit procrastinating and put on that bht3e I've got sitting in my garage.
I won't really investigate too much further until I get thise valve springs on as well, I know you can't take it over 3200 stock without risking some valve floating issues.
By the way can any normal valve spring compressor be used to change these things or do I need to call Cummins and spend $100 ona tool I'm gonna use once?

12valve

i installed a set of 4k GSK, on a friends truck, he says, it will only pull to about 3000 rpm, it is a manual, and he will always shift before it gets to 3000, cuz after it, it defuels.... and it reved up on empty only to 3600 rpm
i dont know why it would defuel so soon.

another question, does that have to do with the turbo as well? his turbo will hit 25 psi max. its some kinda CAT turbo, it works very well, ¿better then the hx35, but it wont make lots of boost, even with the wg disabled.

Willy91

A bigger turbo won't make more boost unless you push more fuel to it.

12valve

ok. believe that. it doesnt really smoke with a 4 plate. and 4kgsk

but then my other qustion, does it need a bigger trubo, to PULL above 3000 rpm?

Willy91

I wouldn't imagine that to small of a turbo will make it rev less, it should just make it hotter and smokier. What do you have your timing set at. If it's stock it wont rev as good as if it was bumped up.

halerazor

i have a 4gsk and can peg my rpm gauge, i'm gueing about 4500 rpm. how tight did you get the springs i tightened mine as tight as i could get them