You paint with a very broad brush, pal. I'll leave it at that because I doubt you would understand the retort.
No worries. I do understand that sentiment though. I sometimes have the same perspective, but it is usually for folks that have never left their cube and or been out in the field.
I’ll never forget the time I got into an argument with a freshly graduated engineer, who wanted to put a 3/4 inch threaded hole in a sheet of aluminum 1/8th of an inch thick, to hold a 700 pound, 150,000 dollar piece of equipment
Are you talking in general or for break-in? I hate to disagree with you but this is bad advice for a break in.
Why? When I was in the test cell for Cummins, it was policy to get them up to operating temperature then do the break in procedures. Not saying you’re wrong, but why are you saying it’s a bad idea for break in?
Wouldn't the mushroom style cam/lifters in the Cummins be a bit different to break in vs a flat tappet?
Every book every artical, every instruction i have ever read for breaking in flat tappet lifters all say to get the rpms up to 2000rpm min as quickly as possible. My luniti instructions even say not to let it idle. Maybe rollers and diesels are different but for flat tappet engines I have always read and heard do not let them idle. Get em up to 2000rpm and get it the running temperature then start the increase of 500 rpms for one min all the way to 3500 then the same back down to 2000.
Do you want a medal or a chest to pin it on???? So you're an engineer that doesn't know about inertia, momentum, and force...
That's ok, I still like to warm up my engines before bringing them above 2000 RPM.... I ran a standard bore 318 up to 500,000 miles on a daily driver... Less friction = less bore wear...
Funny how they don't mention to apply any assembly lube to the cam while installing it... Then don't recommend using break in oil until AFTER the break in... I use beak in oil/zinc additive DURING the break in...
1200 RPM is not idle, and will allow full oil pressure... First start of an engine is pretty hectic; verifying oil pressure, listen for knocks, setting initial timing to get it to run smooth and not choppy or die, verifying no oil, trans fluid, or coolant, or fuel leaks, that's an easy 3 - 5 minutes right there... Then get it up to 2500 and set total timing, then watch the temp gauge to make sure it doesn't overheat... If there are any issues that are critical and make you shut it down to fix so it doesn't blow up, it doesn't matter if you were at 1200 or 2500 RPM before you shut it down... Verify there are no issues before starting the break in...
That is what I'm doing now making sure all the bugs are worked out that I can before I ever fire it off.
Murphy's law... If it can go wrong, it will... That's why you have to check as much as possible before starting it the first time... Then double and triple check before you start it so you don't have to shut it down... I helped a friend start a fresh rebuild and we found out one of the trans lines were leaking like a sieve and had to shut it down and fix the line... Then topped off the coolant and trans fluid and restarted it... Then the carb bowl was flooding over on a 'fresh rebuild carb'... There's always something to go wrong that you have to react to during first start and break in.... Very rarely do things go smoothly on the first try....
You are talk'n about a total differant animal. Most diesel engines have roller cams which require zero breakin. With any engine it is proper to bring it up to operating temp before applying load but it is not always the case. Look what they do to engines on the production line test, no warm up at all. I am also a Cummins Guy as I retired from Cummins Engine 10 years ago. It takes very little run time to flatten a flat tappet cam. It has always been my opinion that alot of flat tappet cam failures are caused by the tappet(s) not rotateing in the lifter bore properly and/or improper lubricant's.
How many car shows have you seen on the TV where they do a cam swap and run a breakin on the cam? Never
You really think the TV shows televise the break in? That's cut out and they usually say "the engine was broken in and now we're doing some power pulls...". I built my stand just to limit the liability with sending a customer the engine and relying on them to get it broken in right. First start is the most risky part. Not the grease, not the break in oil, not removing the inners... Verify rotation, and get it fired with the least number of rotations under 2K as possible.
Aren’t you a piece of work? Pretty sure I get the concepts and am way past the theoretical. Like i said, you do it your way.
A couple of comments. [1] I assume the engines were not pre-heated at the factory before they were fired up & checked. And they lasted for tens of thousands of miles... [2] Roller cams have less friction, post #35. No, actually for two reasons. One, the flat tappet lifter face is convex & the lobe has a taper, side-to-side. This combination allows the lifter to spin, to pirouette like a ballet dancer. Only point contact is made. Over time, as both lobe & lifter face wear, friction would increase. The other friction with a roller cam is the pressure angle. The smaller the base circle, the greater the angle & the greater the levering force exerted on the sides of the lifter bores. On Pontiac V8s that have some of the lifter bores unsupported, & the bores have been known to break from this side force when duration/lift reaches a certain level.
