Opinions on valve springs for hyd roller cam/lifter/rocker street motor

[Ttype6]

Is there a good reason to change valve springs and hardware for less pressure,

If you had some ridiculously high spring pressure for your combo,you could change springs. In your situation,you're right in the ball park. There is no good reason to change them. The springs you have are one of the hand full of spring options that are ideal for your situation. If you purchased springs from another manufacturer,that would also be right for this situation,you'd just have a different set of springs that would also be ideal for your cam. It would be neither better nor worse.

The key is to set them at the proper installed height.

 

[Ttype6]

The 918s arent enough either.

I,m surprised that you say this. I ran these with a 210/215 roller with 1.6 rockers producing .532" lift. I shifted at 5,800 rpm and never experienced any valve float. It seemed to want to rev and rev. I would consider the 26918 springs to be one of the viable options for the OP's cam,but again,no better or worse than the 1201 springs.

 

[87GN_Bart]

I have bought heads from Champion starting in the early 90"s from iron to GN1 and GNR heads. I have never had an issue with the springs they supplied. They always asked me what cam i am using flat tappet or roller whether it's race or street. I put the heads on they way they come and' "O" issues my cars over the years have run from 12 sec to 8 sec.

 

[forcefed3.8's]

You assume they are fine. He set up set of GN1Rs for me and said they are good for a hydraulic roller, and didn't even know what the cam was. I was going to change springs anyway, so it didnt matter. The ability to rev is not a good indication of valve float. There are some tell tale signs of valve float that I have found.

 

[forcefed3.8's]

With that said, I check everything and I have my own pressure targets I shoot for.

 

[87GN_Bart]

Rob i did assume and had no problems however they asked cam size, lift and what rockers i am using and i never had a problem. I agree it should be checked however we rotate the engine set the lash and make sure there is no bind.

 

[broke]

Ramp rate seems to be left out of the equation a lot.

 

[broke]

It seems ya gotta look up lobes in the catalog to find lift at 50 and 200 they only give max lift and duration at 50 in their description. A cam needing way more spring can have a lot less lift.

 

[joed]

Thanks to everyone for sharing this information
So far I've learned..
There is NOT a good reason to ditch the PAC 1201's for my motor
There IS a good reason to take them to the machine shop and get them checked , SET/RE-SET
- I'm taking them on Monday.

Soo, what seat pressure range do I get them set to?
Anything else I have them do or check?

 

[Ttype6]

Ramp rate seems to be left out of the equation a lot.

Along with other comments about Comp Cams incompetents as it relates to valve spring recommendations,my experience is that ramp rates never enter their minds. If someone installs a different cam in their engine and it's the same lift and duration as the previous cam but has XFI lobes,I would recommend 30 to 40 extra lbs on the seat and over the nose just because of the faster ramps.

 

[Ttype6]

Soo, what seat pressure range do I get them set to?
Anything else I have them do or check?

They will be around 140 lbs at installed height but you can't install them at too low of a height. You set them up based on the max lift point. At max lift the springs should be .060" away from coil bind. It's important to get as close as you can to that number because it is important to the spring's longevity that you compress it to its full capabilities. Being shy and staying farther away from coil bind is something that leads to spring failure. Work the spring to its full potential.

 

[Ttype6]

There are some tell tale signs of valve float that I have found.

There is a relatively quiet but audible fluttering sound as the power production hits a brick wall. The very split second that the transmission shifts into the next gear,full power comes back instantly.

 

[joed]

They will be around 140 lbs at installed height but you can't install them at too low of a height. You set them up based on the max lift point. At max lift the springs should be .060" away from coil bind. It's important to get as close as you can to that number because it is important to the spring's longevity that you compress it to its full capabilities. Being shy and staying farther away from coil bind is something that leads to spring failure. Work the spring to its full potential.

Not an engine guy, so not disagreeing here. From an engineering standpoint, that seems counter intuitive. Stress/strain cycle level is inverse to fatigue life. Or does "spring failure" mean loss of k value?

 

[Ttype6]

Not an engine guy, so not disagreeing here. From an engineering standpoint, that seems counter intuitive. Stress/strain cycle level is inverse to fatigue life. Or does "spring failure" mean loss of k value?

I'm talking about breaking the spring.

 

[joed]

Machine shop disassembled today, here is what they found:
Shimmed to Installed height - 1.700 @ 155#
At .500 lift - 1.200 @ 460#
Coil bind @1.100 (see below)
(.496" gross valve lift for my 206/206, lobe lift .320") They are assuming 1.55 ratio? Spring compression must be .496" not .320"? And what if I use 1.65 ratio? Wouldn't the lift then be .320 x 1.65= .528" That would make the max compression 1.700-.528=1.172 that's only .057" from bind.

Here are the specs from Jegs:
PAC 1201 Street Performance Valve Springs
Spring OD: 1.260
Spring ID: 0.770
Seat Pressure: 140 LBS @ 1.750
Open Pressure: 410 LBS @ 1.200
Spring Rate: 540
Max Coil Bind: 1.115
Max Lift: .550

 

[Ttype6]

And what if I use 1.65 ratio? Wouldn't the lift then be .320 x 1.65= .528" That would make the max compression 1.700-.528=1.172 that's only .057" from bind.

It would be .057" from coil bind if you used the factory coil bind specs,but you say that your guy observed 1.100" as the coil bind number. Even if it were .057" you'd still be okay. I would use 1.65 rockers. You'd get everything out of that cam that could be gotten.

 

[Ttype6]

These springs do produce much more pressure than you need. I think the comp 26918 would be a better choice. 460 lbs at max lift is what an XFI lobe would need. This is after all a 5,500 rpm cam with relatively slow ramps and a relatively small amount of lift.

 

[earlbrown]

Do the springs need to be "set up" at a machine shop that TurboNasty mentions? I'm not sure what's involved...

Only if you want it done right.


Here's how I do it. I measure each individual spring installed height and write them down. Then I take note of what valve is the tallest all the way down to the tightest. Then I pick an arbitrary number in the middle of the lift and check each spring putting them in order of stiffest to softest. Then I marry the weakest springs with the tightest valve, and vice versa.

Then I start looking at the poundage over the seat and over the nose. If those numbers look good, I let it fly. If i need more poundage, I'll start shimming. If shims get involved, you have to check for retainer to seal clearance using the actual retainer and locks that you're going to run. If that clearance it too tight (or hits), it's back to the seat and guide machine to lower the guides some more. You literally have no idea if you're done or not until you're done.

If they're beehives, you have to shim them to get them close to coil bind even if that makes more poundage than you want. That only applies to beehives though. Conventional and double springs don't require that step.

 

[earlbrown]

Not an engine guy, so not disagreeing here. From an engineering standpoint, that seems counter intuitive. Stress/strain cycle level is inverse to fatigue life. Or does "spring failure" mean loss of k value?

It's the nature of the design and only applies to beehive springs. Their shape causes the resonate frequency to change as it gets compressed. Iit's main selling point is that it will never see it's natural frequency under use and go limp. For that reason, it's better to shim it more than normal to put it into its range of functionality, than it is it have it '''right'' but not able to change frequency like it needs to.

That methodology does not apply to conventioan single/double/triple springs.

 

[joed]

Earlbrown, thanks for sharing that experience and black magic! I probably can't ask the shop to go through all that! But helpful to know. For Beehives, ignore pressures and set near coil bind (like ~ .060") like has been mention here before.
Cool.