xzaq103

How high can you wind it without valve springs? The thing is im getting A 3k that will fuel to 4k no load and 3600-3700 under load. It’s an auto. Should I be worried about it winding that high with stock springs

94 12valve

I've heard that anything over 3k should be running 60lb springs

12valvesmoke

Valves start floating at 3800

xzaq103

so 3500-3700 is ok??..... I was thinking 3300 was the line I went ahead and got em today couldnt pass the price up. Since i have an auto should i worry about how high they can go?

stock600

Wouldnt chance it at all. You also have the boost pressure to concider, high boost and high rpm with factory valves springs is trouble waiting to happen. The springs are very afforable and not a huge deal to install yourself. Dont risk it. IMO

xzaq103

So would driving it for a few weeks with valve springs be ok?

kas83

Just watch your boost and listen for the telltale popping of valve float. And don't push it. My 97 with stock governor springs and valve springs, will free rev to 3400 or so, and pulls to 3100 no problems. Before I got my wastegate figured out, it would bury my 50 psi boost gauge at 2200, and still pulled like crazy. However, there were a couple times that it would start popping when pushed hard. I have since backed it down, and am installing 60 lb springs while the head is off the truck. The springs cost a little over $100 at the local Cummins place.

xzaq103

How much does it run to get valve springs installed?

wcbcruzer

I wouldn't rev it past 3000 rpms. There's a reason the factory set the redline there. Maybe you can rev a little past that and be ok but why play with fire?????

xzaq103

So if i stay at or around 3k will i ahve an issue with floating valves? It is an auto so it must shift at some time.

Dieselnick

Where'd you get the 60# springs?

Thanks,
Nick

xzaq103

i just got the gsk springs for a good price. I haven’t bought the 60# springs yet.

13th_Samhain

Springs are a good Idea just for high Boost...but unless you got money to burn, 3200 pretty much as far as you should go. The 6B engine usually has a 2500-2650 set limit for most applications. The only app that I know of that is over this is for Dodge trucks, so they are already pushing the limit for the truck engine. The 6B, ISB, and QSB 6.7 in Marine, and Industrial trim are all 2500 RPM engines for durability that the truck engines won't have, and if you have ever held a B series connecting rod in your hand just ask yourself how fast should it really go up and down! 3200+ is begging for a hole in the block and crooked valves.

xzaq103

I don't ever plan to spin it more than 3000 - 3200. Im thinking about selling the 4ks that will spin 3600 under load and 4K in neutral. And buying some 3ks what do you guys think? It would save me the cost and worry about needing valve springs. I guess ill wait to see how much it costs to install valve springs.

What are the benefits of having 4Ks over 3Ks?

wcbcruzer

Only benefit it the higher rpms with 4k's... Also, I heard the throttle is less sensitive with the 4k, which may be a good thing. I know it's hard to watch your EGT, boost, and tach while you drag but if I were you I'd just keep the 4k and watch the RPMs.