What should I do? I have a set of 4K springs should I install them or should I buy some 3ks and sell the 4s? I’m just worried about two things the first is I plan on pulling with this truck sometime soon and I have seen trucks break driveshaft’s trans and transfer cases and let the engine free rev. With the 4ks it would free rev to 4k I don’t want that sense im not putting in #60 springs yet. The second is I have heard about run away trucks. Same thing I don’t want it pegging 4Kwithout valve springs. IS there any benefit of having 4Ks over 3Ks? Besides being able to wind higher? I mean its an auto after all.

 

if you r pulling i would go 4k and install some valve springs and titanium retainers. if you not wanting to go through the trouble of installing the valve springs and retainers, i would still keep 4k. when you are pulling if you leave at lets say 3500rpm your not going to pick up any rpm down the track.your either going to stay at the rpm you launched at or most likely loose a few hundred rpm.

 

agreed... stick with the 4k, i LOVE mine!

 

i had the same questions before i put my 4ks in which came with 12 hd springs from piers diesel, but i haven't put them in yet, and i would say my 4k feels like it pulls harder down low than my brother 3k and i also have an auto and the truck won't go out past 3200rpm unless in drive, unless your doing a burnout and you get to 4th gear at 100+ and a burnout at that mph is bad anyways. but its easily the best thing i ever did to my truck besides the 0 plate or maybe even the timing so far. just put the 4k kit in and don't free rev it too far, because i set mine 5 clicks tight total its really touchy which is how i wanted it, but if i free rev it wants to go way past 3k so i don't rev it much.

 

They are one in the same, leave out the center springs and you have a 3k kit.
Start with them and if you want/need higher rpm fuel add the valve springs and small governor springs later