cam break in...

[DANNY]

Have 1.3 break in rockers already. Starting pulling inner springs but after 2 keepers flew off and fell into motor, luckily it's still on stand and they in the pan so gotta pull it back off. I'm really wondering if pulling the inner springs is necessary?

[stockcar5]

What is your open pressure with the 1.3 rockers?

[Brian Gray]

Roller or flat I haven't used break in rockers or done anything to the springs in decades.

Just use a conventional lube that has a high zddp content and imeadiatly bring rpm to around 2100 . If you did your job right there should be no issues. If the components are of inferior quality your break in procedure isn't going to make a difference.

[DANNY]

Not sure of the pressures on the 1.3 but we checked the springs at full valve lift for the cam I was at #450...

This is a flat tappet... I know I been told it would be good. I never have last one I did didn't even have break in rockers I threw the 1.6u I was going to run on and fired it up...

[stockcar5]

You need to know how much open pressure you have with the 1.3s. If you have your seat and open pressures with the 1.6s and the total valve lift i could figure out what your open pressure would be with a 1.3. A sprint part number would help also. Most flat tappet cam guys dont want you going over 350lbs open during break in.

[Lizardracing]

I would do whatever your cam company tells you to do by the letter. They are going to be more likely to help you out under no obligation IF something goes wrong.

Aside from that....I would do either the 1:3 rockers OR the remove the inner springs. You need some pressure to get the wear pattern established but not so much pressure the lifter and cam are destroyed.

Remember that "breakin" is really just a controlled amount of wear so parts will become hardend, smooth and shiny and will last a very long time. Too much pressure will wear them away to quickly.

[DANNY]

Seated they are #145.

Most likely I will continue with pulling the inners and use the 1.3. Then replace the inners and go again. After that it should be good to go. How would I calculate the open with the 1.3 vs the 1.6?

[Brian Gray]

You multiply the open spring pressure by the rocker ratio. If your open pressure is 450 lbs x 1.3 , 1.5 , 1.6 ect .

[Brian Gray]

When I was doing cup stuff we had to run flat tappets . We had springs in the 7 - 800 psi range with 2:1 ratios and never broke a motor in.

I'm not recommending this just noting the pressure isn't your enemy.

[DANNY]

So with the 1.3 I'm at #345. Not bad

[Brian Gray]

800 psi open witha 2:1 ratio would be 1600 psi.

[Brian Gray]

Now multiply that in series and you will understand why the 55 mm cam core and roller bearings came about.

[stockcar5]

Do not listen to Brian. His math isn't even close and he has no idea what he is talking about.

He obviously never worked in cup. They haven't run those kinds of spring pressures with 2 to 1 rockers ever.

[DaveBauerSS6]

You dont need to pull the inners and run the 1.3. Do one or the other. The 1.3 is the way to go.
We dont have nascar parts machined by a nascar shop. Break in the cam on the 1.3 rockers.

[Brian Gray]

I'm not going to argue but cyl heads was my primary job. And calculating lifter load was a part of life for nearly 12 years. So to make a statement and discredit me is really ignorant on your part.

I did say I didn't recommend this . because in order to have a cam and lifter live in that situation takes some real knowledge of materials and tons of cash. But 4 or 500 lbs of lifter load is not a concern enough to validate the extra work or parts to reduce the load for break in. That's my point and the answer to the question the original poster asked.