Just had my engine rebuilt and requested a mild cam upgrade just to make the engine sound a little better. I have no idea the specs of the cam and had no idea about what it takes to break in a flat tappet. Engine guy said not to let it idle but rev to about 2000 rpm for 20 min. He lubed cam and put break in oil in it. Now I’m scared to death that I’m gonna destroy the cam. I read lots of horror stories about this procedure. My fear is, what if engine doesn’t start right away, and I have to troubleshoot things which requires cranking over the engine many times, will this destroy the cam ? Any experts familiar with this process? I wished now that I had kept stock cam.
It should be fine. There's been a lot of B.S. perpetuated over the last 20 years about what causes cam failures, mainly because cam companies don't want to take any responsibility for it. It's not lack of "zinc" (ZDDP), although you do need a certain amount. It's not lack of cam hardness. It's not usually the fault of the customer or engine builder (although it can be). It's usually caused by poorly machined lifters. So why have cams from so many various cam companies failed? Because most cam companies get their lifters from the same place and put their name on them. If the lifter face is improperly machined, the cam can get wiped. If the lifters are not spinning in their bores, the cam will get wiped. Extremely stiff valve springs for racing applications can wipe a cam. For a mild street cam, you "shouldn't" have any problem if you follow the proper procedures. 20 minutes at 2000 RPM is correct. Prime the oil pump with a drill before firing it up. It doesn't matter if the engine doesn't fire right away (although you want it to). As long as you're not cranking it for hours with a no-start, the cam lube will protect it. I mean, how many RPM is it spinning during start? There's very little friction, and no heat...
Engine is primed with oil according to the builder. He recommended valvoline vr1 oil, 10w40 after replacing break in oil around 500-1000 miles. 10w40 is a little hard to find, may have to switch brands or go 10w30
I have broken in quite a few cams I my lifetime. What the engine builder told you is correct. Don't worry about if the engine don't start at first. It won't do anything. A correctly timed and fueled engine will start right up. Like posted prime it with fuel and oil.
You need the oil to flow as quickly as possible. 5w-30 or 10-30 would be better for this than 10w-40. Change the oil after the 20 minute break-in. Don't run that break-in oil for 500-1000 miles. It will have metallic particles in it. Get that stuff outta there and change the filter too. Use Motorcraft FL1-A or the WIX equivilant. Stay away from Fram. I run Valvoline 10w-30 with Comp Cams ZDDP additive in my Maverick...
The second number in oil is the viscosity when HOT. In other words, 10W-40 flows approx same at ambient temps as 10W-30. The 10W-40 will not thin out as much when engine is hot.
I think there are a number of things that are contributors, but the best evidence I've seen is that badly machined lifters are a major issue like TeeEl said. I've seen some close ups that show actual flat spots and angles on the lifter face, which should be very smooth and slightly crowned. Some lifters have the crown ground off center, all kinds of stuff. No amount of zinc will fix that. If your cam is mild, it may even use stock valve springs, which greatly reduce the odds of wiping a cam. Today's high performance cams with aggressive ramp angles and high lifts require a lot of spring. With those cams it can be advisable to use lighter springs for break in or remove the inner springs from a dual spring setup. Like others said, do what your engine builder advised. Here's some more advice on how to get the engine to start right away, so you're not cranking on and on or having the engine die repeatedly after short times running. http://www.how-to-build-hotrods.com/start-your-engine.html And a couple of YouTube videos from a channel which has some great Ford content.
Lucas Engine Break-In Oil 10631 use it all the time. Works great, I always run them at around 1,500 rpms and rev a little every now and then during break in. Then change the oil and filter. As for starting itself, I always use a points dist since they are a much more sure thing and you don't have to worry about wiring it right, Then after break in, change to what ever.
"Break-in" oil is exactly that. It is designed for breaking in a new or rebuilt engine. It typically has no detergents, and is not meant to be used after the break-in process. For example; Comp Cams break-in oil is some of the worst motor oil you can buy as far as lubrication properties. The idea is to seat the rings against the cylinder walls right away, which requires friction, not lubrication. My understanding is that it contains no detergents. They load it up with 3,000ppm of ZDDP, which is double the amount needed, which is their idea of protecting the cam during this break-in process. I used it when I did a cam swap on my Maverick (before I knew this stuff); the engine was already broken in with 4,000 miles on it. Did not have any problems. but when I did the cam break-in on my Chevy 350 (engine itself was already broken in), I used Quaker State full synthetic 5w-30 with the Comp Cams ZDDP additive. No problems with that either...
Depends, too, on what piston rings you have. Cast iron requires some miles to seat, moly-faced rings seat almost as soon as you turn the key.
".. scared to death that I’m gonna destroy the cam. I read lots of horror stories ... " . . Yes, No, Maybe do this or that ... , there's not too much to worry about startup' if you have a plan and I'd pay attention to the machinists' advice/opinion for warranty. . BTW priming with oil pressure by spinning the pump is not an opinion - it's a necessity. . Initial startup with a total car build is more problematic, any trouble with COOLING system will become evident at 2K RPM quickly. A cooling problem with the Tri-Power Comet 250 six getting hot on break-in was remedied by flooding outside of radiator with a garden hose to complete cam break-in and then fixing the rad/fan control system. . all the somewhat conflicting info can be digested as you listen to the engine at 2K and a get to finally smile and relax. have fun
Just an update and to pass along my thanks for all the info. I got it fired up. Timing was off and it didn't crank right away. I moved distributor around a bit and it fired up. Ran my 20 mins and it appears (fingers crossed) that it's okay. Whew!
