1970 911 2.2 T major engine rebuild - break in period
07-18-2017, 05:06 PM
#1
1970 911 2.2 T major engine rebuild - break in period
Hi guys, as the title says, Just fully rebuild the engine, so now what's the correct "break in" period? How many miles, how many rpm's? General advise for this period?
Thanks for your feedback!!
Thanks for your feedback!!
07-18-2017, 06:01 PM
#2
Team Owner
Waynes book is pretty good on that.
first hook up battery charger and set to 10 amps no more .
1. crank it over with ignition disabled for 30 seconds.
2. stop and go look around the engine for leaks
3 after 2-3 minute cool down for the starter crank again until the green light goes out
if light doesn't go out stop . inspect oil pressure switch and other possibilities for no oil pressure
if light does go out stop and let the starter cool down again , then crank for another 15 seconds.
4. make sure car is outside, hook up ignition and when / if she starts rev it up to 2000 RPM and HOLD. for 20 minutes ..yes 20 minutes .. use a watch so you can keep track. 9you want to keep oil pressure maxed out while cams bed.
( I had a helper keep an eye on things with an extinguisher and set the idle high for me so I could get out of the car. )
change oil after 20 minutes
go for a drive vary engine speed up to 5000 rpm constantly changing gear and engine speed. 3-5 miles ( I stayed close just in case )
check oil level after warm and go for extended drive for 10 miles again constantly increasing and decreasing RPMs
accelerate rapidly as well as coast down a hill in a lower gear to build vacuum and bed rings.
go home and change oil.
let it cool down , next day drive 500 miles fine tuning things like fuel timing leaks etc.
then adjust valves, and while covers are off retorque heads for magnesium case engines
change oil
1000 miles adjust valves again retorque heads, change oil and your done.
I would use dyno oil for all this break in .
first hook up battery charger and set to 10 amps no more .
1. crank it over with ignition disabled for 30 seconds.
2. stop and go look around the engine for leaks
3 after 2-3 minute cool down for the starter crank again until the green light goes out
if light doesn't go out stop . inspect oil pressure switch and other possibilities for no oil pressure
if light does go out stop and let the starter cool down again , then crank for another 15 seconds.
4. make sure car is outside, hook up ignition and when / if she starts rev it up to 2000 RPM and HOLD. for 20 minutes ..yes 20 minutes .. use a watch so you can keep track. 9you want to keep oil pressure maxed out while cams bed.
( I had a helper keep an eye on things with an extinguisher and set the idle high for me so I could get out of the car. )
change oil after 20 minutes
go for a drive vary engine speed up to 5000 rpm constantly changing gear and engine speed. 3-5 miles ( I stayed close just in case )
check oil level after warm and go for extended drive for 10 miles again constantly increasing and decreasing RPMs
accelerate rapidly as well as coast down a hill in a lower gear to build vacuum and bed rings.
go home and change oil.
let it cool down , next day drive 500 miles fine tuning things like fuel timing leaks etc.
then adjust valves, and while covers are off retorque heads for magnesium case engines
change oil
1000 miles adjust valves again retorque heads, change oil and your done.
I would use dyno oil for all this break in .
07-18-2017, 06:20 PM
#3
Thanks Theiceman, that first steps are done, I want your advise on how to drive it for the next, x miles...
For example, I have one opinion that I should do 500 miles not going over 4.000 revs, after that doing 200 miles not over 5.000 revs and than I can start ro floor it a few times....
Another guy told me to do 500 miles 80% at maximum 4.000 rpm, but towards the end, going to max rev sometimes to "loose" the engine....
So, I was trying to get opinion of you guys about this
For example, I have one opinion that I should do 500 miles not going over 4.000 revs, after that doing 200 miles not over 5.000 revs and than I can start ro floor it a few times....
Another guy told me to do 500 miles 80% at maximum 4.000 rpm, but towards the end, going to max rev sometimes to "loose" the engine....
So, I was trying to get opinion of you guys about this
07-19-2017, 09:13 AM
#5
Team Owner
I didn't pay attention to any" rules " after my initial break in. I just didn't drive it like a moron if you know what I mean. Just use common sense.
And drive it without hammering it till you are comfortable.
And drive it without hammering it till you are comfortable.
07-19-2017, 05:14 PM
#6
Quit Smokin'
Rennlist Member
Rennlist Member
There are many many theories on engine break in, most of them will definitely get the job done safely
You certainly do NOT want to do anything to a new engine that you shouldn't be doing to a fully broken in engine. For example, low rpm + large throttle input. Don't lug a new engine.... but also, don't lug an old engine. You also do not want to drive a ton of heat into a new engine. so: no extended flogging, extended periods of high load, climbing a mountain with your foot planted on the floor.
you definitely DO want to vary the engine speed. Acceleration runs increase the pressure of the piston ring against the cylinder wall, so some bursts of acceleration help the piston rings seat against the cylinder wall when the cylinders still have a fresh finish. Technically if you take a brand new engine and do the first 1000 miles easy on the highway you could smooth out the cylinder wall prep without getting the rings seated. Typically when I have new rings I will do a couple full throttle pulls from say, 3500 to 4500 and then 3500 to 5500, quick bursts in second gear, and I let the engine run down from the peak RPM with a closed throttle. Supposedly the closed throttle vacuum pulls oil up to cool the rings back down. And again, this is not repeated thrashing to heat soak the parts, it's just a a couple quick rips every drive...and of course this is after the cam break in cycle, and a couple heat cycles around the block.
Most things that would fall under common sense will work fine for your new engine. In all honesty if you use your 911 for country roads and in town, just drive it the way you always would drive it. If you drive like me, and tend to run things pretty hard, then a more metered break in is prudent.
NO LUGGING and NO HEAT SOAKING, and you'll be fine
You certainly do NOT want to do anything to a new engine that you shouldn't be doing to a fully broken in engine. For example, low rpm + large throttle input. Don't lug a new engine.... but also, don't lug an old engine. You also do not want to drive a ton of heat into a new engine. so: no extended flogging, extended periods of high load, climbing a mountain with your foot planted on the floor.
you definitely DO want to vary the engine speed. Acceleration runs increase the pressure of the piston ring against the cylinder wall, so some bursts of acceleration help the piston rings seat against the cylinder wall when the cylinders still have a fresh finish. Technically if you take a brand new engine and do the first 1000 miles easy on the highway you could smooth out the cylinder wall prep without getting the rings seated. Typically when I have new rings I will do a couple full throttle pulls from say, 3500 to 4500 and then 3500 to 5500, quick bursts in second gear, and I let the engine run down from the peak RPM with a closed throttle. Supposedly the closed throttle vacuum pulls oil up to cool the rings back down. And again, this is not repeated thrashing to heat soak the parts, it's just a a couple quick rips every drive...and of course this is after the cam break in cycle, and a couple heat cycles around the block.
Most things that would fall under common sense will work fine for your new engine. In all honesty if you use your 911 for country roads and in town, just drive it the way you always would drive it. If you drive like me, and tend to run things pretty hard, then a more metered break in is prudent.
NO LUGGING and NO HEAT SOAKING, and you'll be fine
