I have the 977-16 springs from comp cams. After talking with comp yesterday, I find out that they are not usually recommended for hydraulic roller cams because the hr cams are supposed to have about 130 seat psi, and these springs have 160 at 1.850". They said I'll have to have mine opened up to 1.900" for them to be at approx. 130psi.

Question 1: Is the stock valve stem length enough to get 1.900" of install height?

Question 2: What are the negative side effects of having a little to much seat pressure?

I have comp "R" lifters and a cam that goes to .575"/.595" with 1.6 rockers...

I can't say for sure since I have aftermarket valves. But checking my notes I have mine set at a range of 1.88-1.85 the most variance per cylinder is .011". This is as close to being equal that I could set them up with a good barrel micro and a set of .015 shims to use for adjustment. 1.90" may be a bit tall for the stockers

I would be more concerned about excessive open PSI, but you did not show that. I would think it could be over 400-425lbs! which is a lot for a street engine with a desire for durablity and reasonable service life. What is the listed open pressure with your cam's lift at a 1.90" (or a 1.80) installed height?

I am not certain but I would think premature valve train wear would top the list of negatives of having too much pressure. You might wipe a cam lope or wear out a lifters in half the normal life (whatever a normal is?).

I agree with Don, your lifters would ear sooner, and the cam lobes might also exhibit excessive wear. You can get diffferent locks that let the spring move up some, but I dont believe it would be .05.....

You can get locks that change install height .050 but you wont be able to run SA rockers beacause the valve tip will be too short.

Kevin

Good point!

Maybe he can gain some height by using titanium retainers. Am I correct in believing that they might be thinner and allow a higher install height?

I beleive that they are slightly thinner but the height change comes from the lock seat location, meaning that the locks sit deeper in the retainer. Another problem then occures whith SA rockers, the alighning washers on the rocker will sit on the retainer and thats a very bad situation.

thanks for the replies guys...

I wasn't able to check in today since I've been in the garage all day. I'll have to see what happens with the springs. I supposed I could order different ones, but I have the titanium retainers that I believe are designed for these springs. Would it hurt to put a different spring on this retainer? I guess what I'm asking is, are the retainers specific to each spring.

I was told that these thing would work for me. damnit. I hope they do. I won't be installing the springs until tomorrow or saturday anyways, but I'm hoping they work out...

I don't know what your defination of to much is but a solid roller runs 250-300+ on the seat. You have a roller cam so cam wear is not a factor.I run between 125-150 on the seat when new without any problem.Springs will loose a few pounds after the first few heat cycles maybe 20-25lb's
You could get .050 up keepers and/or retainers but you run into problems with the rocker clearing without a lash cap.I would run it just like it is and see.I don't think the extra 30# or so are going to bother it.It WILL be less after a few miles.

I don't understand your comment about "you have a roller cam so wear is not a problem" . While roller cams have less friction than flat tappet cams, there is still friction and thus wear with a HR cam. I always thought that higher spring pressures enable higher rpms, but at the cost of greater wear of the components.

Also, I understand that springs loose a small portion of their listed psi after a few heat cycles, but cam manfacturers take that into consideration when they spec a spring's open and close psi to match a cam. I believe for a street vehicle there is not much to be gained by exceeding the recommended psi but potentially much to be lost in the service life of the valvetrain.

Ok, heres what I did. I called up my spring guy and bought a different set of springs. Basically the same spring but with a lower pressure rating...

Part #: 978-16
OD: 1.460"
Max Lift: .700"
Seat PSI: 150 @ 1.800"
Open PSI: 400 @1.200"
Bind: 1.140"

I think these will work much better. I plan to install at about 1.850" which should get me down at or near 130 seat PSI without needing the .050" over locks, and then with a max lift of .595" on the exhaust side, I should have an minimum open height of about 1.250" with a pressure of a bit less than 400 PSI...

I don't mind having a little bit to much psi, cause i want to be able to rev it up a bit, but I just don't want the comp r's to collapse on me. I think these new springs will solve that problem...

400 is a bit much on the nose for a hyd cam,you need to cut that down.




DON 97 SS

The cam makers only know what the spring is when they made it,and that is the only spect you will get.They don't ALLOW for anything.They would have all kind of problems if they did,like people calling and saying my springs only lost 16PSI and you said between20-25PSI.
I don't understand about the wear answer you gave,Are you not thinking.A BIG solid roller runs in the neighborhood of 300+LBS on the seat and 700-1000LBS on the nose with no wear damage so what makes this small cam different.Is this one of those THING I HEARD ABOUT that people take as GOSPEL?

I don't know if this helps or not, but...

Back when I was running my old cam (Crane's GM 847 clone), I ran K-Motion K800 valve springs. 165# @ 1.850" installed, 470# @ 1.150" open. Everything worked fine, but the K800s kept collapsing my OEM replacement lifters. When I took the cam out to sell it, there wasn't any extra wear on the lobes or anything. Atljar (Jared) is still running the GM 847 with K800s and Comp R lifters and hasn't had any problems. I plan on staying with the K800s for my new cam when my engine goes back together (242/248 0.575"/0.600" with 1.6 rockers)...I'll be running Comp Rs with that setup.

I don't know about all of the technical details, but in practice, it seems like running extra spring pressure doesn't excessively wear on anything (other than lifters, but the Comp Rs can take it).

Don,

Not to bust your ***** here but before you get on RacerDude's case you might want to know that he's not just some internet expert. The guy has been around engines for a long time, one of those guys who can tune a mechanical fuel injection and a carb.

Back on to the Hyd Roller seat pressure debate....

155lbs on the seat is not too high on a HR setup. The problem with a HR is that if the lifter is not made well then the plundger and spring in the lifter might colapse causing big problems. The good thing is that on somthing like a Comp R they hold up to the pressure so you can run a lot of seated pressure.

As Racerdude said big SR setups can run lots of seated pressure, sometimes in the area of 400+ if the cam is a big drag racing setup. NASCAR boys use 260lbs on the seat since they have more of a durability concern. More pressure means that you wear out the roller in the lifter faster, not wipe out cam lobes, that will happen with too much pressure on a flat tappet setup. You can run lots of pressure on a flat tappet cam too, but you need special oil additives and a very careful break in procedure to get it all to work and NOT wipe out the cam.

As for over the nose side of things, 400lbs is going to be common on something like a 977 spring setup, plus the higher the rocker ratio the more the lifter and pushrods see, and at that point deflection of the pushrod is going to be your enemy.

If it was me I would set the springs up at 155lbs on the seat or whatever the cam manufacture and designer call for. 155 is not that high in all reality.

Bret

It's funny... these questions seem to come in pairs. There was a similar thread here a few days ago.

The cam companies from most of what I've seen are a bit conservative in their response but that's to be expected. Most of them will say something to the effect of "excessive valvespring rates cause accelerated bobe/lifter wear". So there's no real secret about where the confusion stems.
Personally, I'd run a bit more spring than is required (or suggested) because I have never seen a situation where it cost power..... only helped it! From the research that is available now, you'll see that Spintrons have shown that valvetrain motion seems to be more controlled with higher tension springs.

I agree that there's going to be more friction/heat so you need to get the heat out and thats where having the oiling system up to snuff is important. More oilflow = more heat carried away. You also want to control oil aeration or you're going to have some problems but these new engines have very good windage systems in place already.

All said, I shoot for 150-160 lbs on a good lifter.

-Mindgame

Bret,
Thanks for the kind words.


I was unaware that Comp's lifter's could stand 400 on the nose.Guess I need to use some and see what they will take. In the past,around 375 has been my cutoff point with factory lifters,anything over that I go to SR.
Ran 140&370 on a 10# blower engine and made over 500RWHP and the owner tow's his offshore race boat around with it(26 ft.) and runs 7.35-7.45 every pass in a 4600LB truck 1/8 mile.Thats on pump gas & 20.000 miles later it is still going strong.

Thanks again