Race engine break in with flat tappet cams.

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Sep 9, 2003
I'm new here and did a search on this subject but didn't find anything specific. I build and dyno test race engines, most with flat tappet cams and high spring pressures. I normally use a 10W diesel oil (Cenex 518) for break in and Amsoil 20-50 Series 2000 or 5-30 series 3000 after. (Break in, for me, means the first 30 minutes of engine run time and maybe a half dozen or so partially loaded pulls on the engine.) It's my understanding the reduced zinc oils are mainly the 30 weight variants of gas engine oils, the S rated oils in 5-30, 0-30, 10-30 etc. This is why I have got in the rut of using the Cenex 518 10W for break in. The last few years I've been paranoid enough about ruining a cam to add a bottle of Sealed Power LL-5 to the break in oil AND the Amsoil. I have a dyno test coming up on a Engine Masters Contest entry and for break in the engine builder wants "any name brand 10-30 from Walmart". I'm having a fit. I think since he wants a 10-30 I'll use Cenex 518 10-30, or better, the 518 15-40. The engine has Schubeck lifters in it because we will be testing a few different cams and with the Schubecks the AW additives (or lack of relative to flat tappet cams) shouldn't be an issue but paranoia is a hard thing to suppress. The final cam will use conventional all magnetic solid lifters. So are there any specific suggestions or thoughts on this subject? Thanks, Jesse Lackman [ September 12, 2003, 12:13 PM: Message edited by: BOBISTHEOILGUY ]
Jesse, [Welcome!] If you have had success with doing what you are doing, why change? Dont you know more about building engines than a customer? I have built a couple of motors and just break them in on havoline 10w-40 with a good filter, then change to synthetic at about 3000 miles in the car. Impressive setup on the web page. Dan
That oil seems light, IMHO. Why the 10W for cam break-in? Don't most cam companies recommend a 30W or 40W straight weight for flat tappet cam break in? Also, I thought the Schubeck tappets, besides being reusable, eliminated break in and or having to use reduce ratio rockers of lighter springs? I'm not saying what you are doing is wrong, just want to know why the choice for that oil. Have you looked into cryogenic tempering of engine parts and what do you think of this for flat tappet cams & lifters? Mondello told me that in their experience, a flat tappet cam & lifter set after freezing, required no special break in (treat it like a roller) and they got 2-1/2 times the life out of them. I am considering this for my next cam. [ September 10, 2003, 01:33 PM: Message edited by: goatdude ]
Well first thing is you use low pressure valve springs for cam break in ,and use the cam break in lube as per cam manufacture and use an oil with high anti wear additive levels that is it. I would use h.d. 30 wt. or 15w/40 oil.
Well it's settled on 15W-40 diesel oil. I've always broke in flat tappet cams with light springs. goatdude the cryo treatment sounds interesting, I have heard of it but not specifically for cams. Thanks for the replies.
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