cam break in

[benno440]

just reading the cam card and instructions on my lunati hydraulic flat tappet cam.

it says to pull the inner springs out on my valve springs when i run the cam in as it wears better.

i also have comp roller rockers.

DO I really have to do this because what a pain in the *** this will be, what do you guys think???

 

[Meep-Meep]

The short answer is you should remove the inner spring. The long answer comes with an explanation on what actually happens between the lobe an lifter interface.

The flat tappet cam and lifter is actually sort of a bearing. The lobe is ground on a taper and the lifter face is crowned so the contact pattern is on the edge of the lobe. This relationship causes the lifter to spin in the bore as the lobe lifts the lifter. When the parts are new the amount of surface area at the point of contact is pretty small, or you can say less than ideal to allow the film strength of the oil to protect the mating surfaces, and with high valve spring pressures the situation is much worse. The cam break in period burnishes the two surfaces together making that contact point wider thus creating a better bearing surface, and the film strength of motor oil is sufficient to keep things happy for a long time. This is also why you want to run an oil with proper additives, or even pumped up on steroids so to speak, on initial start up.

So how do you kill the cam in the driveway? One way is to have the lifter not spin, and it is possible that too much spring pressure on a narrow surface that pierces right through the oil film is a pretty good recipe. All it takes is something to make that lifter not spin and you are done.

 

[mopar367]

I took the inner springs out on mine to break it in. I haven't had a chance to put them back in yet though. I'd rather take the extra time and energy first. Than replace the cam and have to do the extra work again anyways.

 

[fatecaptured]

Sorry for hijacking the thread

 

[383man]

It would be a good idea to remove the inner springs to break the cam in. I did and I use oil with alot of the zinc and added a bottle of the zinc additive.
This tool I bought from Mancini racing made the job much easier as you run the allen head screw down to push the valve spring down. And then you can use both hands to remove the retainer and keepers. All the others I use you have to keep one hand on the lever bar and only get to use one hand to do it. Dont remember what I paid but its worth every penny. Ron

 

[Cranky]

I have an OTC two jaw tool. http://www.summitracing.com/parts/otc-4573/overview/ Works ok so long as the spring pressures are not out the window. I've used roller cams before and probably will again and won't have to worry about all that other stuff.

 

[Meep-Meep]

Very neat valve spring tool Ron.

 

[benno440]

what do you use to stop the valve from falling in the cylinder?

 

[moparmarks]

what do you use to stop the valve from falling in the cylinder?

A fitting that goes into the spark plug hole and connect an air compressor to. Presserise the camber keeps the valve in.

 

[RustyRatRod]

Remember though, if air is all you use to keep the valve from falling, at least run that cylinder's piston up to TDC in case the valve falls anyway. It will keep it from disappearing. Although the seal would probably hold it.....it pays to be safe.

 

[67 B-body]

Another old trick to keep valves from falling is to shove a section of small dia rope in through the plug hole, filling it up. Just leave a tail hanging out so you can retrieve it when your finished....