Ok Some of you mechanics and high Hp guys help me out here. (lmills, cquestad) In simple layman's terms what is the purpose and goal of springs and cams? I have been reading the 230 hp race tune from mads and it states that you will need springs.... Why? Is this an inferior cummins part or is it just safe to change and get out of the way when you get over say the 600 hp mark??

Thanks fellas for teaching!!!

Shane

 

not to but in but isnt the race tune the onw that does 4k???? if it is i think that is why you need springs

 

the pistons and valves will make contact when running high rpms

 

stock springs are too weak to close valves quick enough before piston hits them at high rpms. As far as cams go if you change the duration on the lobes you can hold the valve open longer to force in more air.

 

Not inferior Cummin's design as they work for what was designed by Cummin's. If you redesign one part of the system you often need to make design changes to other parts to take advantage of the first change.

Would you ask the same question about the turbo? If you really want the HP you will not get it with a stock turbo.

 

It's simply a matter of keeping the cam follower in contact with the cam lobe and the valves away from the pistons. The lobes on the camshaft open the valves by pushing on the follower or lifter. This pushes the pushrod that pushes the rocker arm that pushes the valve. The spring is on the valve and pushes the whole mess back as the cam rotates on around. When the cam is rotating fast enough it will open the valve so fast that the valve will open farther than the cam lobe pushes it or remain open a bit longer than the lobe is holding it. The momentum of the valve lifter, pushrod, rocker arm and the valve itself exceeds the pressure exerted by the spring. This is called valve float. When that happens the valve may contact the piston and the cam follower hammers on the camshaft. So it's damaging to parts and may lead to a big failure like a valve head breaking off. This is what generally limits how fast an engine can turn itself.

On a gasser, for instance, you can rev it up in neutral until it takes on another sound and won't rev any farther. That's when the valves are floating. A normal car engine might do it at 5000 or 6000 rpm and the Cummins will do it somewhere past 4000 RPM. At 4000 RPM the valves are cycling at 2000 times a minute.


John

 

they rock yeaaaaaaaaaaaaaaa the stock springs will also bind up at high rpm and lead so some major problems. if you want to play you got to pay love mine

 

Not to jack the thread, but how many RPMS are the stock valves good for, can i just put in springs and not worry about the valves bending or breaking at the 4000 RPM range? rods?

 

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Thanks man....!!!

 

Did you installl them yourself or have someone do them??? I figure if I am going to be doing head studs in the next month or when weather straightens out I might as well dive in!!! If you did how hard was it??

JSteiger have you done yours???

 

Nope... haven't installed springs in my truck. I don't think I really need them unless I need to spin over stock rpm. <---- note I said "need" versus "want"

I am also kind of wondering if they are needed with consistently high boost levels even though the rpm level remains stock?

Anyhow, I helped Christian install his springs. It was easy with the head off though. We installed bottom tapped studs, injectors, springs, and a new head gasket in his driveway one Saturday afternoon.

If I remember correctly, you have to remove the injectors in order for that Cummins 4-spring compressor tool to be used. So to make this project worthwhile, I think you need new injectors too.

 

Well injectors and studs are next on the list... Studs should be here monday or tuesday... I have been talking with Nathan and Christian on which size of injectors to get so I might as well do all three at once eh..... How much beer do I need

 

Its just like your truck. You dont need any, but you modify for the great feeling of satisfaction in a job well done and a having good performance.

I always modified myself right up to when they stopped sellin beer. But at that stage I was never ready to perform.