Engine break in

malcons66 · Jan 23, 2006

ill have to try that next time... or will i dun dun dun

jerry S · Jan 23, 2006

this topic came up here before and one of the contributors to the thread posted this link. At the time, my engine was still being assembled so I called the shop building it and repeated the key points of this article. The shop basically agreed. So the advice to "drive it like you stole it" for breaking in a new engine is also out there.

http://www.mototuneusa.com/break_in_secrets.htm

69Rcode_Mach1 · Jan 23, 2006

Yes I am in the same boat as well. If the clearances in the bearings are correct, run it hard. In fact I would recommend getting it on a dyno, it will put a sufficient load on it throughout the rpm range and seat those rings up nicely. Read that link Jerry posted it is full of good stuff. Ronstang also recommended I do it that way, he has been doing this forever so he knows his stuff. That is how the Mach1 is being broken in.

NasaGT · Jan 23, 2006

rbohm said:
assuming the rebuilder didnt break the cam in, then you need 20 min for cam break in(run at 2000 rpm minimum and dont let the engine idle in that period). after the cam is broken in you can dyno the engine.

Not to hijack, why does a cam have to be broken in >> 2000 rpm for 20 minutes? I have never heard of this before...

cobains_dad · Jan 23, 2006

hey guys i just talked to the garage and he said just break the cam at 2000 rpm for 20 min or so that should do the cam and get on the hwy and
start off at 30 and hard to 50 or 60 or so and then back down to 30 he said do that 4 or 5 times and that should seat the rings

iskwezm · Jan 23, 2006

NasaGT said:
Not to hijack, why does a cam have to be broken in >> 2000 rpm for 20 minutes? I have never heard of this before...

as the cam spins at a faster rpm the lifters rotate in the lifter bores, if it idles,they dont spin and get worn and get flat.Thats why lifter should ne numbered when removed and re used,they get a pattern to them.

dennis112 · Jan 23, 2006

NasaGT said:
Not to hijack, why does a cam have to be broken in >> 2000 rpm for 20 minutes? I have never heard of this before...

Non-roller require a break-in period for the cam lobe and the lifter face.

The high RPM is to needed to keep the cam lobes oiled, because the only way they get lube is from the splashing of the crank and the rods.

Comp Cams suggests 2000 for 30 minutes in their installation instructions, although most people seem to use a 15-20 minute timeframe.

NasaGT · Jan 23, 2006

Ahhh, thanks iskwezm and dennis112!

69Rcode_Mach1 · Jan 23, 2006

cobains_dad said:
hey guys i just talked to the garage and he said just break the cam at 2000 rpm for 20 min or so that should do the cam and get on the hwy and
start off at 30 and hard to 50 or 60 or so and then back down to 30 he said do that 4 or 5 times and that should seat the rings

I would recommend doing it more than 4-5 times. The first 20 mile are the most important, but you want to run it hard for the first 200 miles. Get on the freeway and get on all the gears and run them through the whole rpm range, that is the most important. Now if you have overdrive don't worry about going 140mph, but atleast make a blast or two through your 1:1 ratio gear, 4th if its a manual, and 3rd if its an auto. Do not brake, rev it up there and let the rpms drop, let the engine get loaded down and slow on its own. This will ensure the rings get a maximum load put on them and you will be good to go.

12sec67 · Jan 23, 2006

67coupe351w said:
other says break the cam in and run the engine as hard as you can (WOT or dyno) within the first 3 hours or so of its life.

The theory behind running the engine hard is that under high load the rings seat into the walls better while the hone is still on them providing a better seal for the life of the engine. light load or no load simple wipes the hone off the wall.

i installed my roller 347 drove it around the block a few times and have been getting on ever since...no problems here

i have approx 700 miles and 2 oil changes on it now (one after 100 miles then again at 300) and have drove it to the track on 2 different occasions and still tuning

ozstang65 · Jan 25, 2006

NasaGT said:
Not to hijack, why does a cam have to be broken in >> 2000 rpm for 20 minutes? I have never heard of this before...

It's a surface hardening process. Blatantly plagarised from somewhere I can't remember:

"The most critical part of the rebuild process is starting the engine for the first time and this is where many well meaning mechanics go fatally wrong. You MUST NOT let a newly fitted cam run at idle speed for the first 20 minutes of operation. Always keep the rpms up at about 2000 during this period. At idle speed the loadings on the cam 'nose' (that's where the cam is at full lift) are at their highest and the new cam can suffer permanent damage if it is allowed to idle before it has bedded in and work hardened properly. Sitting on the driveway with your foot on the accelerator for 20 minutes can seem like an eternity. Also if the engine starts to overheat it may be necessary to switch off, let things cool down and split the process into several shorter intervals"

I think it's a very wise move to dyno run-in an engine, and it should be budgeted into an engine rebuild. On a dyno, everything can be analysed very accurately. One of the biggest killers in a new engine is incorrect a/f ratio. This can be picked up immediately on a dyno.

Speaking from my own personal experience, I was once of the misconception that it was best to take it easy on an engine run-in. I rebuilt the engine in my Falcon (6cyl) and babied it during run in. It uses oil and has a light fumy smell. I had the head off a few years ago and I could still see the hone-marks in the bore. Now we all know hone marks are there to help bed in the rings. Trouble is, they should dissapear during this process!

Mine will be run in on a dyno. (Hopefully very soon )

Edbert · Jan 25, 2006

I'd hold off on the dyno myself, not for a break in reason but because the engine will still be "tight" and will probably post lower numbers than it would with a thousand miles under it's belt.

I mean, the purpose of a dyno run is to see how much power you are making right? You can use other tools to determine A/F ratio, which I agree is very important.

ozstang65 · Jan 25, 2006

Edbert said:
I'd hold off on the dyno myself, not for a break in reason but because the engine will still be "tight" and will probably post lower numbers than it would with a thousand miles under it's belt.

Why would anyone be worried about 'numbers' during a run-in, I just want to make sure my engine's running right and not doing itself any damage.

A lot of people have a misconception about dynos. The truth is, they're just a tuning tool, used to compare your 'untuned numbers' with your 'tuned numbers', to make sure you are actually making improvements with you tinkerings. Unless you are comparing 2 cars on the same dyno at the same time dyno 'numbers' are meaningless, albeit giving you a ballpark figure. Even taking your own car to the same dyno under different atmospheric conditions will yield different 'numbers'.

Really, at the end of the day, is it dyno 'numbers' that are important, or how quickly you can make those 'numbers' get you from point A to point B.?

Edbert · Jan 25, 2006

ozstang65 said:
Why would anyone be worried about 'numbers' during a run-in, I just want to make sure my engine's running right and not doing itself any damage.

Agreed, that was my point

Tuning can be done without seeing any hp/tq numbers, so why use a dyno in the first place? I guess if you have carte blanch access to one then it is a great tool, but around here dyno time is expensive. They charge by the hour and by the pull. Why do that if you don't want to see the numbers and even the numbers you DO see are meaningless on a tight motor? If you intend on changing jets and advance springs while at the dyno to eek those last couple of ponies out then you can expect a bill in the hundreds. A great tool, I'm not arguing but not the best route for a simple break-in, at least in my opinion.

I plan on doing a 30 minute cam break-in, then maybe 5-10 miles of driving around the block and checking for fluid leaks etc., then hitting the freeway for some ring-seating under load.

351LX · Jan 25, 2006

There has been a lot of talk lately about how modern engine oils don't have the same amount of zinc in them that the old oils had and as a result there have been a lot more flat tappet cam failures on break in.You might consider using one of the off-highway motor oils that contain zinc or adding a can of General Motors Engine Oil Supplement during break-in.

Cobain03 · Jan 25, 2006

do you think i should use our farms oil then? is 15w40 synthitic and is good up to 12k miles or so.

if not, what oil should i go with? i dont mind having to buy a "starter" oil then getting more onces its broken in.

iskwezm · Jan 25, 2006

Cobain03 said:
do you think i should use our farms oil then? is 15w40 synthitic and is good up to 12k miles or so.

I heard you NEVER use synthetic on break on, i used Castrol for break in because it was on sale and i changed the oil after the 20 minute break in, after 150 miles and after 500 miles.Its cheap enough and takes maybe 15 minutes

Cobain03 · Jan 25, 2006

can anyone varify?

69Rcode_Mach1 · Jan 25, 2006

Yes DO NOT use synthetic oil. Run regular oil, and don't switch to synthetic for a while. Atleast wait a couple thousand miles, otherwise you will cause the rings to glaze over.

65up2d8 · Jan 25, 2006

Yes, do not use synthetic during break in. It will not allow the rings to seat because it is so slick. I have always been told to use a straight 30 weight non-detergent oil during break in, but perhaps you should seek your engine buider's opinion.

Engine break in

malcons66

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jerry S

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NasaGT

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iskwezm

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