Cam break in. What's the right way?

What is the best procedure to break in a flat tappet cam?
•Charge the oil system immediately before starting, via the oil drive shaft under the distributor.
•Start and run at 2000 rpm for 30 minutes. Use an IR heat sensor gun to look for hot spots. Worry if you see over 220-230°. Heck, you'll worry anyway. You should have a 190° thermostat.

And what's a good zinc additive to run? Do I run it just for break in, or all the time? How much lube is too much/not enough?
•ZDDP or something similar. Comes in a small bottle correctly size for typical engines.

I'm thinking about saving a few hundred extra and going roller, but man I want to get this thing done ASAP, and that would set me back a while.
Nothing wrong with flat tappets, many were excellent even by today's standards.

too much cam lube is not a problem. use a good cam and lifter "moly" break in grease and vary the rpms for the first half hour or so. do not idle the engine. the range should be 1500 to 3000rpm or so max.

i use brad penn racing oil for break in. it has zinc in it and is good stuff.

once you have run the engine at varying rpms for a half hour or so, change the oil and make sure you take it easy on throttle for a bit.

Put lube on cam lobes and set up at TDC. Put lube on lifter bases and put cyl 1 lifters in. Set preload or lash depending on solid cam or not. Turn engine 90 degrees and put in next in firing orders lifters with lube on base, then another 90 degrees and so on. Use a good oil and some crane or comp cam additive or other zddp additive. They suggest to use it every oil change. If you are running double valve springs remove inners for break in. Pre-prime oiling system prior to starting. Set distributor for quick startup. USE QUALITY LIFTERS?? How do you know?? Beats me. Was told by a cam manufacturer here the biggest cause of failure was due to cheap chinese lifters with a low carbon content?? Once started bring up to approx 2200 rpm and vary up and down to 2000 for 20 to 30 mins. Keep an eye on temp and if you have to, do it in two goes. Also keep an eye on oil pressure of course. After break in change oil and filter. Just on the ZDDP subject, there is a big thing about there not being enough in the new oils. Which is what the cam companies are claiming, but when I rang the oil tech lines they all say they havn't changed their zinc levels. Maybe thats only here in Australia.

In saying this, I have done it by the book and still wiped a cam. Then I have broken in cams that have had troubles starting etc. no additive and it survived no probs. Heck I have an uncle that changed a cam and didn't know you had to break in and that new lifters be used. He put it in and then give it a good thrashing and it is still running strong!!

I have seen 5 cams in total fail, all have been comp cams?? that may only be a coincidence. Four of them solid flat tappet cams on a clevelands with high lift and the other on my buddy's 347 SBF with hyd flat tappet.

I've had two cams each wipe a single lobe and lifter. That was due to the lifter not getting spun by the lobe at fireup. The culprit was too much lube on the lifter and lobe and the use of that same lube on the lifter sides. I use a thin film of lube on the lobe and lifter bottom only, motor oil on the lifter sides and bore walls. And make certain the lifter spins freely in it's bore, when you slip it in. One cam was a Crane, the other a Comp. The Comp failed from the lifter lube on the sides. The Crane failed due to me not waiting for warmer weather to fire it up. Temp was in the low 30's and the motor oil was cold and thick.

when i lube a flat tappet cam, i use a good assembly lube that is designed for cam break in, but can also be used for bearings. this lube is more liquid than the moly lube used on the old days. for the initial break in i also use a can of ZDDP for the first 20-25 minutes depending on what the cam manufacturer recommends for am initial break in period. after that i change the oil and use a can of STP, usually the blue can, but the red can is also good as it has more ZDDP in it. dont forget to keep the engine rpm above 2000 rpm for the initial break in period.

All good points above. About the only thing I haven't seen mentioned is that if you use a cam that has dual valve springs (not not talking about a single spring with a dampner), you should remove the inner spring during initial break-in. Then reinstall the inner spring and then do another 20 minute or so break-in. Even some of the stiffer single valve springs should be removed in favor of a weaker spring just for initial break-in.

Always stay at 2K-2.5K and vary the speed every few minutes. It is OK to shut the motor down if you need to fix a leak or something, but when it it fixed, bring the speed back up to 2K without allowing the motor to idle. Then continue with the break-in.

As mentioned above, lifter must rotate freely (very important!) Cam lube only on the bottom of the lifter and oil on the side.

dennis good point on the valve springs, i would however suggest that you only go with lighter springs if the spring pressure over the nose is above 300lbs. less than that and even with an inner dampner spring there should be no issue.

rbohm said:

i would however suggest that you only go with lighter springs if the spring pressure over the nose is above 300lbs. less than that and even with an inner dampner spring there should be no issue.

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from my experience and from talking with several engine builders the cut-off is in the 340# open range.

I have done several break-ins recently with comp 926s with no problems.

Thats not to say you don't have added insurance running less spring (even heard of using stock springs for break-in) but you can get away with somewhat of a decent spring on a break-in.

68stang351 said:

They are TrickFlow's springs that came on these TW heads.

1.47 o.d. single spring
110lbs. @ 1.8 installed height
305lbs. @ 1.260 open
360lbs. per inch rate

Would they be okay for break in?

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You shouldn't have any problems with those provided you use the break-in lube, ZDDP additive and proper RPM procedures but what cam are you running?

Kind of small springs unless the cam is pretty small.

One more tid bit of advice.........Inspect the lifters, paying close attention to the bottoms before committing to using them. That was another possible culprit in cam/lifter failures, (poorly machined lifters) That could have been the reason in my case too, but I'll never know as I never took the time to inspect any of them. Just never occured to me at the time to do so.

57fairlane said:

from my experience and from talking with several engine builders the cut-off is in the 340# open range.

I have done several break-ins recently with comp 926s with no problems.

Thats not to say you don't have added insurance running less spring (even heard of using stock springs for break-in) but you can get away with somewhat of a decent spring on a break-in.

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i tend to be a bit conservative with things like this. as for using stock springs for break in, i would as long as they dont run into coil bind.

68stang351 said:

They are TrickFlow's springs that came on these TW heads.

1.47 o.d. single spring
110lbs. @ 1.8 installed height
305lbs. @ 1.260 open
360lbs. per inch rate

Would they be okay for break in?

Thanks for all the help guys. These are the kinds of responses I was looking for!

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those springs wont work on the cam you selected as they coil bind at .540" and your cam has more lift than that. however if you swap out to a 1.5 ratio rocker arm for break in they will suffice. you can then swap to a proper spring for your cam and go back to a 1.6 rocker arm.