340 break in question

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gzig5 said:
You paint with a very broad brush, pal. I'll leave it at that because I doubt you would understand the retort.
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People give me weird looks when I say I get paid to color
 
dukeboy_318 said:
Haha I actually do get it. Relax, I’m just toying.
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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.
 
gzig5 said:
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.
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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
 
krazykuda said:
I let the engine warm up to full temperature before going to 2000 RPM or revving it.... I keep it at 1000 - 1200 RPM until it reaches temperature and the thermostat opens...

85% - 90% of engine wear happens when the engine is cold and the friction is higher... The faster you rev it, the more forces are on the moving parts, especially the ones with shear (rubbing) force acting on them... When you let the engine warm up before letting the rpm's get too high, it will last longer.... When the engine warms up, the friction goes down and less wear....

My #1 rule: NEVER REV A COLD ENGINE!!!!

If you rev a cold engine you increase the wear on the bearings, cylinders, crank, cam, etc.... Warm it up first, then rev it all you want....

Do you jump right out of bed and run a mile immediately??? No, you wake up, drink some orange juice, stretch a little, then run...

Same with an engine, it needs to warm up....
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Are you talking in general or for break-in? I hate to disagree with you but this is bad advice for a break in.
 
dartfreak75 said:
Are you talking in general or for break-in? I hate to disagree with you but this is bad advice for a break in.
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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?
 
dukeboy_318 said:
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?
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Wouldn't the mushroom style cam/lifters in the Cummins be a bit different to break in vs a flat tappet?
 
dukeboy_318 said:
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?
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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.
 
Even summit says to get it up immediately! Lol

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gzig5 said:
I'm talking because I'm an engineer and have been designing, building, and working on production and manufacturing machines for 30+ years, most of which use plain bearings and all have splash and pressure lubricated sliding surfaces..
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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... :rolleyes:
 
dartfreak75 said:
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.
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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...
 
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krazykuda said:
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, 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...
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That is what I'm doing now making sure all the bugs are worked out that I can before I ever fire it off.
 
dartfreak75 said:
That is what I'm doing now making sure all the bugs are worked out that I can before I ever fire it off.
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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....
 
dukeboy_318 said:
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?
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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.
 
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I8NEMO said:
Hi all,
Sunday I decided to hook up fuel and start the 1969 340X for the first time, what a glorious sound, and a milestone for this build. A substantial inlet bowl fitting leak shut things down and kicked my butt for the next hour so the run time was all of 15 seconds. This is only the 3rd new motor ive started in my life so I have limited experience but am aware of cam flattening dangers. My touted and experienced buddy who ( has built countless sprint car and hot rod engines)built the motor has cautioned me in that the assembly lube is probably gone now and no more dry runs, the next time it fires, it's gotta go 15 minutes at 2k rpm which I plan on doing. Needless to say im feeling some stress.

What has been your experiences breaking in new engines and having to pause? I can add, the build sheet is still awol so I don't have compression or cam specs. If your wondering here's the complete engine story which explains my apparent casualness and ignorance of the internals - in 2014 I had a truck fire in my warehouse, sprinklers killed the fire, enter fire restoration, so the whole building was gutted. I asked my buddy Bob if I could store my 340 parts at his place for awhile during fire restoration. Unbeknownst to me he went ahead and built this motor as a surprise and at no cost. This thing sounds like a high strung beast, lots of cam lope, just sounds incredible. Im back to only 4 or 5 hours of sleep like a kid waiting for Santa.

Thanks

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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.
 
krazykuda said:
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... :rolleyes:
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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.
 
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