What valve springs should i choose?

[Caprimaniac]

For a Comp 31-761-8 Magnum solid roller; what valve springs should I use?
I will turn 8000 r's. Cam is NOT a billet core.
Not much street use.
Reliability is a factor.
Nothing but a poll.......

(Engine have been running 8000 rpm with springs weaker than this (145 closed 385 open) without any NOTICEABLE, by the ear that is, valvefloat.)

Rocker ratio may be moved from 1.6 to 1.7 as well.

The two first are suggested by comp cams.

Looking forward to get some opinions.....

RS

[blykins]

This is going to be a love-hate relationship as you need adequate spring pressure to keep the valves in the right spot at rpm, but that cast core cam isn't going to like the pressures that you're going to need. It will start flaking.

For a 1.900" install height on a Victor Jr head, I would at the very least run a Comp 954 spring (and probably shim them up .030"). However, the 991 spring would be one that I would towards using for an engine pushing that kind of rpm with a solid roller.

The whole system really needs to be critiqued to make reliable power at this kind of rpm.

[Barry_R]

Need to know your installed height first. Makes a big difference. Might want to look at the Manley Nextec springs for the LS engines - lots of development going on there. The 221435-16 is a 1.340 diameter double that gives 170@1.811 installed and 446@1.110 with a coil bind of 1.05.

[Caprimaniac]

Well, Barry. I am not sure if I understand what the concern is with installed height....
I will shim the springs to spec, might also measure rate (if I buy in a preassure checker).

Also forgot to say; will have Ti retainers (and locks) + shaft mounted rockers.

It gos as follows:

Above values are for springs installed at

1: 1.800"

2: 1.850"

3: 1.900"

[blykins]

He's just saying that springs are designed for a certain install height.

You wouldn't use a spring designed for a 2.000" install height on an engine that mics up at 1.700", etc. This would wreak havoc on the spring pressures and coil bind clearance.

The springs that he posted most likely wouldn't work for your application as the Victor Jr's have a 1.900" install height out of the box. Unless the valves have been changed or the heads modified, this is most likely what you'll encounter. With that in mind, you need to pick a spring that is inline with that spec.

The springs that Barry mentioned are a much smaller diameter dual spring, so lighter retainers can be used, spring mass is lower, etc. This helps on required spring pressures; just like using a beehive spring.

[Caprimaniac]

Yup, OK.

How much smaller diameter are the Manley springs?

The comps are 1.489, 1.460 and 1.55

[Barry_R]

I put it in the response - 1.340. I'm trying to find you a package that will keep the pressures safe for that non-billet core and still maintain control. Reducing the retainer size & weight is a way to cheat on the pressures a bit. A 1.900 original height against a 1.811 target ain't that bad - a -.050 retainer or keeper and a single .030 shim gets you right there....

[Caprimaniac]

Am a little worried about the non- billet material after what I've read here and there. On the other hand, it's been working well for a while.

Ny input on moving to 1.7 rocker ratio in this regard? I'm not TOTALLY disapointed at the performance as is, so I don't see 1.7 ratio as a must. Thinking of moving on to a billet core grind "next time".

[Caprimaniac]

MAN-221428-16 150 seat 355 open 341lbs
Installed 1.800"
Diameter 1.311"

Scorpion SRP1521 160 seat 435 open 408 lbs
Installed 1.800"
Diameter 1.300 424$....

Lunati list their Pacaloy beehives for solid roller
(160 closed 425 open 408 lbs 1.950" installed)
??? Anyone in for this???

[Caprimaniac]

Only 3 votes? Oh, you leave me with even harder choices than before the vote!

Barry; thank you for your input, which is helpful. Do you think the 221435-16 will be safe & OK for this cam?

RS

[blykins]

I don't think they'll work with your heads....you'd basically have to shim them up .100" to get them to the specs that Barry posted. Considering that you'll have to run a spring cup or locator, you're taking a good chance of not letting the valve seal get a good bite on the guide...and it will pop off.

The first step before you order any springs is to take a closer look at your heads, measure the install height, and then go from there.

[Keithc8]

Not enough information to give a good suggestion. Just get a steel core and be done with it. I can not see any of the springs controlling the valves at 8000 rpms unless that is one really smooth low lift camshft. If that is the case it will not make power anywhere close to that so why turn it that high. If I had shaft rockers and wanted to turn 8000 rpms I would get a better camshaft where I could run at least 200 to 220 on the seat and about 600lbs open. Do this all the time on circle track dirt cars and run them all year long. Just depends on the power you want and what you plan on doing with the engine.

Good luck, Keith

[Caprimaniac]

Maybe that's the way, Keith...

Ok. What about a Crane solid roller? They're supposed to be billet (8620) steel.
368601, 448601 or 448511? It's kind of funny, these cams use 130/ 402 springs, even softer at closed than the ones installed right now.....

And, let me know if I'm completely wrong, 351W cams goes straight into the 302W. And then firing order should be changed at the dist.

But then I think; it's all been working fine till now. Why not just move up to comp's "premium choice" of springs and put on a set of titanium retainers????

[blykins]

Ok, a couple of notes and thoughts.

*351W and 302 can use the same cam. You would also you use the same firing order as you're using now. 13726548.

*You're not making power at 8000 rpm with the cam you're using now, or the cams that you've listed. (They don't have enough duration, lift, or a tight enough lobe separation to do what you're wanting to do.) I don't really know why you feel it necessary to stress the motor that hard, but you'll need a lot larger cam, better flowing heads, lot heavier valve springs, and a lot better valvetrain to make reliable power at 8000. All you're doing now is exercising the tach needle and putting undue wear on the engine components.

*If I could make a suggestion, I would suggest that you take a step back, figure out what you really want to do with the engine, then contact an engine builder that does this every day and just have him set you up with all the parts necessary to make this an easy swap. Keith, Barry, or I would be more than happy to help you with this.

[DAVID GAGNARD]

While it may have been working for you, I just don't see how you can turn your motor or any motor 8000rpms with only 145 lbs. of spring pressure on the seat......that's the amount I run with a hydraulic flat tappet camshaft........

I don't have the cam card/specs with me right now, there are in the shop, but my last 2 solid roller camshafts, Comp and Lunati called for a minimum of 200 lbs. of spring pressure on the seat and I have a 7000 rpm chip in the MSD box........they were both installed at 215 lbs. of spring pressure on the seat...........

David

[Jerry Clayton]

Just set the tach up for a 6 cylinder and you can easily turn 8000 rpm

[madmaxx]

Blykins gave the best advice of anyone, contact one of the reputable engine builders on this site and let them sell you everything, cam, springs, etc. At the rate you are going, the way I used to be, all you do is become a test engine for all the manufacturer and waste alot of money and time and in the end if you do get it running an unreliable engine. The cam is the brain of the engine, the odds of a shade tree mechanic getting the right design is less than 2%. You would be amazed, the builders I have used on this forumn charge close if not sometimes cheaper than summit and you get their knowledge for free.

[Caprimaniac]

Here's some pictures of some of the cam lobes on the Comp non- billet solid roller cam and the Comd solid roller (not pressure fed rollers) lifters. These parts have had two + 1/2 seasons of track use + 2-3 on/ off seasons with not very much use

http://www.clubcobra.com/forums/album.php?albumid=635

Sorry if pictures are too small; will add other formats if any interest.
(Will have to upload to server; cannot upload from computer - why I do not know... And now I cannot add pictures from a CC salbum either; let's try once more! Invalid file! Let's forget it. I'll post the link and read some more on uploading to the forums...)

[Jerry Clayton]

Your cam doesn't look bad for the time you have on it

The choice of what valve springs to use brings many questions to the front as there are so many varibles to consider---
You are looking for shaft rocker arms
You need to check for pushrod /intake manifold interferance where the push rods go thru the manifold by the intake ports---if they need some offset , you will need to take that into account when you make your rocker choice---also the under side of the rocker to valve spring retainer clearance--smaller diameter springs help in that case
You will probably want to run lash caps on the valve tips---Manley has a super set up fpr the retainer/lash cap and it would compliment there spring. Its called Loc-cap---
On aluminam heads you will need a hardened steel locator cup for the lower end of the spring--this will typically take up .060 of the installed height available, so it may be necessary to use some retainer or keepers that allow for extra height or to reduce it.


SOooooooo I guess you (and others) can see that its more of a question about the complete valve train than just a question of should I use this or that spring---

[madmaxx]

If you change cams you need to get away from the POS SADI "cast iron" cams!!! Anyone (comp) will make you a steel billet for about $30.00 more!!! the cams doesnt look bad to me, keep running what you are running.