[pontiacman63383]

Hey guys. Just got the heads back from the machine shop. They are 4x head (7h id number with screw in studs) I am running old faithful with 1.65 rockers. install height on springs is 1.600. I need help picking out springs but I also am looking for info as to why you recommend said springs. I'm looking for info like what kind od of seat pressure is recommend with hydro roller cams along with open pressure. Do I need to adjust my install height? So someone please give me a lesson on how to chose valve springs. thanks guys!

[76 poncho]

See the thread . going ol faithful any advice. Whole topic is descussed. It's just down a few threads from yours

[ponjohn]

http://forums.maxperformanceinc.com/...d.php?t=784905

[b-man]

I'd say 1.600 spring installed height won't be enough, probably at least 1.700 is needed.

Why not just contact Dave at SD Performance who came up with the camshaft you're using and knows the correct springs needed and take the guess work out of it?

[455rebel]

I've always used the cam mfg spring recommendation.

[blykins]

I can help....

What's your cam specs?

[Cliff R]

They really don't make a spring that's a good fit for the OF cam with 1.6" installed height.

The Crower 68404's may have enough room if you are only running 1.5 rockers on it, but I much prefer to a higher installed height, as it opens up options for better springs and more room to grow with that cam choice.......Cliff

[blykins]

It's really easy to manipulate the install height by .050" or even .100" depending on which lock and retainer you use. Plenty of valve springs out there that would work in the 1.650-1.700 range.

[jonmachota78]

You need at least .060" clearance after subtracting valve lift and and coil bind from installed height.
So 1.6 - .650 - .060 = .89
You need a spring with no more than .89" coil bind and probably at least 150lbs at your 1.6" install height. Like cliff said, ain't gonna happen. And if you did find a spring that can fit those parameters, even with offset retainers and locks, your most likely going to be crashing your retainers into your valve seals....
To run that cam with 1.65's your looking at longer valves, or cutting the spring seats IMHO

[blykins]

I'm not familiar with this "Old Faithful" camshaft, so I was thinking something with around .550-.580" lift.

If you are looking at .650" lift at the valve, then no, I don't think you're gonna get there from here with the valves that you have.

So, what is the OF cam?

[grivera]

Originally Posted by blykins

So, what is the OF cam?

According to SD's site: 236/245 dur @ .050" lift .578"/.582" lift with 1.52 ratio rockers 112 lobe sep

http://www.sdperformance.com/viewPro...productID=1816

[blykins]

Originally Posted by grivera

According to SD's site: 236/245 dur @ .050" lift .578"/.582" lift with 1.52 ratio rockers 112 lobe sep

http://www.sdperformance.com/viewPro...productID=1816

To the OP then.....I would be looking at the cylinder heads to see if it's even necessary to run a 1.65 rocker. If the heads have been flowed and you can see a substantial flow increase from .550 to .650 valve lift, it would be something to weigh the pros and cons of.

If you gain single digits or lose flow at that lift, I certainly wouldn't go to the trouble of running a higher ratio rocker.

[Steve C.]

blykins....

They are Comp Magnum High Lift hydraulic roller lobes 3122B & 3120B

.3800" / .3830" lobe lift.

As mentioned in the link above Dave Bischopp states he often uses the Crane 99893 springs installed at 1.780-1.800".

At 1.785" installed height I've seen them at about 145 lbs on the seat after run in with that spring.




.

[pontiacman63383]

Cam specs are
236/245 dur @ .050" lift .578"/.582" lift with 1.52 ratio rockers 112 lobe sep*
I am running 1.65 rockers. So if im needing 1.7-1.8 install height can i machine .2 off the heads? If so will i have a clearence issue with valve seals or is it best just to get new valves and if so how do i know what the install height will be to order?

[blykins]

Are the 1.65's set in stone? Is your install height measured with a locator/spring cup?

You have to watch really closely about cutting the spring seats that amount. There are things that lie underneath that you don't want to hit.

I would look at a +.100" set of valves.

[pontiacman63383]

Install height mesured with factory locks and retainers. Yes the 1.65 are pretty much a for sure. Push rod holes widened and I have the rockers already. So if i go with the off set .100 valves you guys think i will still have the clearance with valve seals

[blykins]

Originally Posted by pontiacman63383

Install height mesured with factory locks and retainers. Yes the 1.65 are pretty much a for sure. Push rod holes widened and I have the rockers already. So if i go with the off set .100 locks you guys think i will still have the clearance with valve seals

Here's your options...

Most of your tool steel and titanium retainers are +.100" height. So you have that.

You can get valve locks in +.050", but you have to watch about retainer to rocker arm clearance with those.

Potentially, you can get an extra .150" in height, but by the time you buy titanium or tool steel retainers, you would well be on your way to a set of valves and a valve job.

More than one way to get there though.

A couple of other thoughts....

1. If you do overcome the install height/coil bind clearance issue, you do still have to watch out for retainer/seal clearance, but you can always have the guides cut down so it would lower the seal.

2. If you don't have a spring locator/hardened shim/spring cup factored into your install height, you probably should. Hydraulic roller spring pressures are higher than your flat tappet stuff...

Is the cam set in stone too? If not, there are many, many lobes available that would cut the lift down.

[pontiacman63383]

Cam is installed already. So its looking like new valves. I did not account for anything in 2. Ca. You give me a run through of what they are and why i need them. (Ive never run a hydro roller cam before)

[blykins]

Your normal spring pressure for a hydraulic flat tappet would be 90-100 lbs seat and 260-280 open (or less). On a hydraulic roller, you have a more aggressive lobe, a heavier lifter pair, and you need to run more valve spring pressure to account for it. I'm normally anywhere from 130 lbs seat to 160-170 lbs seat depending on the lobe, and anywhere from 320-330 to around 400 open.

Those higher springs pressures and bigger valves springs can induce some wear between the spring and cylinder head with those scenarios, so it's common-place to use a spring locator/cup/etc. to locate the valve spring and to keep it from not playing nice with the spring pocket.

Obviously, this is a lot more important with an aluminum head, but still a factor with cast iron stuff.

Your typical spring locator is .060" thick and that needs to be accounted for when measuring install heights.

[pontiacman63383]

Alright everybody, crisis averted! The joy of being a Pontiac pack rat is I have about 4 other sets of heads. started pulling valves out and found a set that will have in install height average of 1.77. So I now have the clearance I need. Sucks I will have to have them cleaned and seated but this will be a lot cheaper then a new set of valves. Now with the info everyone has given me. So looking online I have two sets of springs I like and would like you feed back. First is crane cams 99893. 130 lbs @ 1.850. second set I'm looking at is comp cams 914-16. I bit high on the pressure I believe. 165 lb @ 1.800. I think im going to shoot for an install height of 1.800. what do you guys think?