Engine/Transmission (1994 - 1998) What is needed to safely run 4k gov springs?

[FreeBMW]

I long for higher top speeds and longer gears... ... therefor i am thinking of switching out my 3k for a 4k kit. The question I have is... ... Is it safe to rev a 12v out to the 4k range? i remeber readign that somthing really bad happens around 4100rpm. do i need to do anything to the valve springs first?



any/all info would be great!



Thanks

Clayton

 

[Tardog]

I've heard of guy's runniung the 4k set up in the 12v. Some say they they can't get the valves to float others say they can. I think performance wise upgraded valve springs are in order. The 4k spring kit from Piers comes with a 12pc set of HD valve springs. The complete kit is $260us.



http://www.piersdiesel.com/DodgeUSPrice.htm

 

[JohnE]

Simple rules: install 60# valve springs (intake & exhaust) and keep it less than 4,100 rpm.

Switching out a 3k for a 4k set is very simple. It only requires adding a small spring in the center of each stack. Voila, 4k springs.

 

[Deezul1]

I wonder if my springs have been changed as I have run mine to 3500rpm with no valve float. How can you tell if they have been upgraded, I bought it used.

 

[Andy Redmond]

Often the valve springs will have a white line painted on them.



Should you go to a cummins dealer and compare them the coils are larger as well.



A valve spring tester would tell the tail for certain. .



I keep the 60# springs, if your in Dallas, swing by and take a peek at one.



Later

Andy

 

[chrleb1]

#60 springs are a nice safe guard. 3,400 is a good number to keep under if you have stock springs. If you are planning to run up that high and have a manual, missing a gear could spell disater. i think there is a problem around 4,200 rpms. Funny things start to happen with the engine harmonics. If you are going to spin that high, make sure you have a turbo that can flow enough air.