When it comes to coil bind, is there any give...or are the tolerances very tight.

If a set of heads are set up with springs that accept a maximum of .550" lift and the cam advertises .558", will there be a problem?

I have a really good line on either a set of 200cc runner aluminum Vortec heads set up for .550" of lift, or a spring kit for iron Vortec heads that accept .550" maximum lift. Both are good options and a good deal, but the cam I'm looking at advertises .558" of lift.

Confused about the tolerances when it comes to that last .008".

Thanks guys.

 

I think you answered your own question, you'll have coil contact with that cam. The only way to be sure is to measure the actuall coil bind with the current spring setup.

 

You need at lease .060 before coil bind. You would need to check them to be sure and not go by advertied maximum numbers. But in general you will probaly be just fine. There are cheap load meters around that you use with the spring in a vise and they are ok but not the best for sure. The best way to set a spring is to coil bind it in the vise and bact the vise off the .060 safety, read that presure. That would be your max open presure. Now back it off the amount of lift for your cam and read that presure that is your max installed seat presure. If these numbers fit your cam spec's your in. Good luck.

 

I called a local machine shop and he said basically what you did. The .008 difference would probably not cause a problem.

 

However all but the best springs will loose pressure starting with just the first few cycles....... couple of thousand miles later and you can expect to loose 10% of your original seat pressure......

Personally and from past experience with minimum springs loosing pressure over time I would say you are asking for trouble to go with what is already by manufactures specs to be falling short on minimum requirements.

To much spring pressure is not a good thing and without a billet cam will result in premature cam wear HOWEVER NOT ENOUGH SPRING PRESSURE WILL EVENTUALLY RESULT IN CATASTROPHIC FAILURE AT HIGH RPM

Doug

 

Use good springs and if the heads are properly setup for a .550 lift cam and your running 558 lift I really don't think you will have a problem. Just check for coil bind before ordering the cam.

 

If you are ABSOLUTELY sure that you will NEVER even approach redline, then you MIGHT be OK.

Sorry, DB, that sure doesn't sound like you (or me, or most of us here!).

 

Well this may have all been moot. I just got an email from the business selling these heads and for an extra $30 they will include .600" lift springs.

 

DB, if you know what cam specs you have now. You can shim up some feeler gauges on top of the valve after the lifter bleeds down and turn the engine to open the valve to .558. From their you can check for bind and valve seal interference. BACKYARD TECH

 

Sweet - go for it!

 

Make sure the closed and open pressure and spring rate are correct for your application. 1.6 rockers will work with those springs and cam too. If your buying rockers anyway it is some free power and get you closer to optimum open spring pressure.

 

Float the valves a teeny bit one time. It'll clean out your bank account fairly efficently.

Coil bind is when the spring is fully compressed and becomes a solid little block of very high quality steel.

Part of that is the reason I keep saying to get the cam/lifters/springs from the same manufacturer. Nobody listens and everyone wants to argue, but by getting it all from one place, the whole show matches and is designed to work together.

 

It is nice to go that route. See my last post. If the heads come assembled and it saves you money make sure they are a good match for what is recommended for your cam. DB never runs his car over 6000 anyway....................yet.

 

I rarely push my engines up past 3500. I like to cruise and enjoy the low end torque. I'm not an HP nut, and I don't do flat out high RPM runs much.

 

Make sure they match the cam, now you almost .050" extra lift on these springs, do you think the seat and open pressure are higher than the .550" lift springs ?

My new heads are coming without springs so I can get the correct ones that are specified for the cam I am running

 

Well, the cam says max lift is at .558". Is there a better spring than the .600"? I asked the shop selling the heads for springs appropriate for .558" lift, and they threw in the .600" springs. Do they make .560" or .570" springs to be more exact?

Maybe I don't understand what you mean.

 

Cams need the correct springs. One reason I can't stand buying fully assembled heads is that I usually have to spend another 200 bucks to get the springs I want.

At .550 lift you start getting into the territory where it becomes much more important to have the correct springs. There are many variables with the springs, including but not limited to seat pressure, open pressure, installed height, spring rate, coil bind etc etc. All of these specs are taken into account when a cam manufacturer recommends the springs for the cam.

Take a look at the specs for the recommended spring for your cam and see if they match the springs coming with your heads. That means you need the specs for the springs, to say they are good for .600" lift cam doesn't give you the info you need. They could be solid roller springs and the open pressure would be too high and your hydraulic lifters wouldn't even work properly

And yes they do make .560" and .570" springs, Comp Cams has a thousand different springs and and spring combinations ( dual and triples ) but they only recommend one set for each cam

When looking for springs I usually look for similar open and closed pressures and well as spring rate, then I calculate the max lift the spring can handle

 

 

Never, never run lifts higher than the recommended max for the springs.

Then check everything. Years ago AFR put the wood to me on a set of roller springs on AFR210 heads. I discussed with them exactly what i was doing and they sent me .600 lift springs for my .620 lift cam with 1.6 RR. I had the heads on the car and TQ down when I first found out that I could not rotate the motor after i set the lash on the first couple of valves.

 

I just got off the phone with the shop selling the heads, and spoke to a tech from Crane. The .600" lift springs that will come with the heads meet all the requirements of the Crane cam. Looks like that parts all good now.

Thanks everyone.