L20B break in

[TheBirdistheWord]

Maybe its the key words im using, or not using... tried a search with no luck with specifics to a bored L20B

 

86mm repco L20B pistons

rebuilt A87 head

polished crank, clevite mains and rod bearings

 

general vibe ive picked up on the interwebz seems to be "drive it like you stole it" it regards to breaking in a rebuilt/built motor.  Driving through the entire rpm range hard and letting the engine break your speed through all the gears. I am unclear about first starting the motor up after assembly and installation.  Is there a, for the lack of a better word, "Prime" method before I actually start it? Are there any signs I should be looking for that the rings have not, or are not seating correctly? how many miles is recommended for break in? 

 

any other information would be greatly appreciated! 

[Eagle_Adam]

You got it man, drive it like you stole it, no consistent RPM's

[red76datsun]

high RPMs low IQ. words to go by!  crank it up

[wayno]

You need to prime the oil pump, that means you need to take it off and submerge it in oil till it is full, then put it back on the engine before starting it.

After you have a couple hundred miles on it at the most, change the oil.

Are you using a new cam, if you are, use delo400 diesel engine oil, or something with a lot of ZDDP additive in it.

My machine shop guy told me to break my fresh LZ23 engine in by driving it normally, he told me that the parts he buys are of such good quality, that the engines are almost broke in when you start them, he said that the parts(rings, ect.) sold these days are just better.

 

Edited the ZDDP additive part, not "zzp" like i originally posted.  :)

[datzenmike]

It is possible to assemble the timing cover without the distributor or the drive spindle for it. Pour oil into and fill the oil pump, then mount it. You can then chuck a long screwdriver in an electric drill and reach in and spin the oil pump to push oil through the motor to prime it before starting it.

 

As soon a possible after warm up get out and drive it out on the highway if possible. Try to keep the revs above 2K and accelerate in 3rd gear to 5K and let off letting the car slow by itself back to 2K and repeat. 3rd is a good gear for the highway as it takes a longer time and the engine has to work harder longer than a quick blip through 1st and 2nd. Full throttle will force the new rings hard against the cylinder walls wearing off the microscopic high points and fully seating the rings for a tight compression seal. Deceleration relaxes the rings and allows oil to lube and flush away any particles. 

 

At all times keep an eye on water temp and oil pressures if you have a gauge. If it has water and oil you can't do any damage to the motor. Avoid extended idling and steady high revs. Keep the revs constantly changing with lots and lots of shifts. Accelerated where safe to do so and you don't have to do it all at once. Just accumulate 30 or 50 good hard runs. If it runs slightly hot, allow it to cool down between runs. If you can only drive in town be extra careful and accelerate in first and second but you will have to do so for much longer to get enough time in. Cops will also see and hear you and there are speed limits so use caution.

 

 

If you are out for a morning or a day (even better) get that oil and filter changed as soon as you get back. Do not break a motor in with synthetic motor oil. Have several thousand miles on your motor before switching to synthetic oils. If you drive it hard I would consider it broken in in a couple of hundred miles.

[MicroMachinery]

I prime the system with one of those bug sprayers with a hose and brass fitting that threads into where the oil pressure switch goes. The oil pump should be full, too. What I do is put the entire 4.5qts into the bug sprayer that will be used for startup, and prime the engine that way. The oil you use is really important, also. If it's a new cam, you'll want to use special break in oil with a high ZDDP content(flat tappet cams like it). If not, I usually use something like straight 30 for the initial break in. DO NOT USE SYNTHETIC. Also, when priming the system, as I watch each qt. go out of the sprayer and into the engine, I turn the crank 1/2 a turn so that all lobes in the cam get thoroughly covered as well as the bearings with oil(some people don't do this, but it's my preference).

Once everything is set to go, go back and double check EVERYTHING: Fuel lines, coolant lines and level, spark plug wires, points gap(if running points), choke operation, fuel level in carb(you don't want to have to crank the engine too much to fill the carb) , etc..

If everything is where it's supposed to be, fire it up. If everything is as it should be, you should have fire in the first few cranks *If it's a new cam, you'll want to run the engine at an RPM no less than 1500 for the first 15min to keep the cam oiled!* When you start it up for the first time, you want to make sure that you have oil pressure within the first few seconds(I usually run a mechanical gauge for this, but some people just rely on the switch.. a little ballsy if you ask me). It's absolutely crucial that you have good oil pressure off the get-go. If that's good, it should be idling high so as to keep the oil pressure up. Make sure that there is no oil/fuel/coolant leaking from any of the lines or connections(keep an eye on this, as they can develop over a few minutes, even if not showing up at first) With a timing light, check and make sure the timing is where you want it. If she's running nicely, keep an eye on the temp and let her get warm, but not hot(thermostat needs to open!).

After around 15min of successful operation, I'll shut the engine down right away and drain the oil and remove the filter. Install a new filter and add oil(No longer straight 30 at this point; I run Delo 400 15w-40), then if all was OK before, I dial in the carb and take her for a spin, varying in speed and RPM. The RPM I run is between 2-5k(the higher the RPM, the more combustion forces the rings out and against the cylinder wall), and then on deceleration, I let the engine do most of the braking, not relying so much on the brakes(this causes a high vacuum in the combustion chamber, which draws oil up onto the walls, washing away ring material that remains on the wall, as well as lubricating). I do this for about 500 miles, letting the engine idle as little as possible. I keep it close to home at first, then slowly move further and further away if nothing bad happens(oil leaks, overheating, burning oil, etc..). Keep a close eye on the temp. and oil levels during this time. The engine will also feel "tight" for the first while, and will run a little warmer than usual. As the miles go on, it will "loosen up" and feel better. After 500 miles, I drop the oil out again, change the filter, and go another 1500 before another oil change. After that, it should be as broken in as it's going to get(I've been told that more than 90% of the break-in is accomplished in the first 10 miles).

[TheBirdistheWord]

wow, thank you guys for the responses.  Oil pump/system is primed already,  used 30w valvoline conventional since im in California and its September. I am just waiting an the correct water pump to be able to start it.  The point of slathering moly grease over the bearings is the protect the surfaces on initial start up until oil can fully reach it them correct?  

 

im anxious to start this thing to see if I did everything right!

[datzenmike]

Assembly lube is fine. I've pulled wrecking yard motors apart that have sat for years and years and all had wet bearings. Motors last hundreds of thousands of miles and have been started in all conditions of temperature and time and they work just fine.

 

The oil used during the first few hundred miles of the break-in isn't that important. I use Chevron Delo 400 which is a 'light' diesel oil that still has some ZDDP in it's formula. The point here is that the oil needs to be changed to get all the break-in crap out! Metal particles, assembly lube, loosened metal chips/dust, condensed combustion blow by gasses. Always replace the oil filter, always! And spend at least $6 on one.. this will eliminate most of the crap filters like WallMart Frams.

[MicroMachinery]

used 30w valvoline conventional...

 

That will do just fine. Valvoline is decent oil. The type of oil that goes in your engine is always important, as is the quality of filter you use. There's garbage oil out there that you don't want in your engine EVER(especially during break-in!), but it looks like you know the difference since you didn't go with Pennzoil or Wal*Mart bottom-shelf brand. Also it's important that if you plan to use synthetics, that you don't use it until after the break in period. Higher ZDDP levels are good for our flat tappet cams, as most modern conventional oils have been formulated to have reduced zinc levels(as it damages catalytic convertors), so it's important to look for something that won't wear down your engine while it's supposed to be protecting it.

[Eagle_Adam]

Some serious knowledge here..... Awesome :)