Best engine break-in method if cams aren't new?

Basic tech questions such as future setups, different turbo kits, car diagnosis, etc
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modulation
240sx Wannabe
Posts: 114
Joined: Fri Jun 12, 2015 4:55 pm

Best engine break-in method if cams aren't new?

Post by modulation »

Block bored .020 over. New pistons, rings, rods, new bearings. Head was refreshed, but I'm still using my old 248/248 cam setup.
Since I don't care about breaking in cams, do I still need to run engine with no load from 2-3k for 20 or so minutes and change oil? Or should I just fire it up, fix timing, and go for a drive as soon as possible to put load on the engine and seal rings?
Going to use T4 Triple Protection Conventional 15W-40 for break-in oil.
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NukeKS14
240sx Wannabe
Posts: 157
Joined: Thu Jan 09, 2020 8:33 pm
Location: Northeastern KS

Re: Best engine break-in method if cams aren't new?

Post by NukeKS14 »

Id do a short run, 10 mins at least at 2-3k to clear assembly lube and then change oil. I do highway pulls and coast down then accelerate again once drivetrain is fully warmed up for the first couple hundred miles or so. Come straight home and let the car sit overnight until cold iron to allow rings to conform to cylinder walls. Broken my last 2 engines in like this (NA LS3 and my KA-T) and they run wonderfully. No engine decel. No constant rpm cruising. Change oil and filter again at 500 miles. Its a pita but kaind of my ritual now.
modulation
240sx Wannabe
Posts: 114
Joined: Fri Jun 12, 2015 4:55 pm

Re: Best engine break-in method if cams aren't new?

Post by modulation »

At what point do you normally see oil pressure? Can you see it while just cranking with starter, or do you have to actually start engine to see it? Do you normally pack the pump with grease or anything?
NukeKS14
240sx Wannabe
Posts: 157
Joined: Thu Jan 09, 2020 8:33 pm
Location: Northeastern KS

Re: Best engine break-in method if cams aren't new?

Post by NukeKS14 »

When i rebuilt my most recent KA I redid the oil pump with new internals. I packed just the gears with grease and rotated it by hand before I put the cover back on. I disconnected the CAS at startup to prevent fuel and spark and cranked it over a few times at about 5 second intervals with a short break in between. Saw small oil pressure the last time, (like 5 psi or so) reconnected the CAS and fired it up. I get about 45psi at idle cold and 17ish fully warmed up with about 55 to 60 at max warmed up around 3500+ RPM. Oil temps in the summer get up to about 190F if I am beating it on the highway (setrab oil cooler helps) My oil pressure sensor is where the dummy oil pressure light switch used to be. I Teed off of there for oil feed to turbo, removed the dummy switch and light, and put my oil pressure sensor there on the t. My oil temp sensor is in my Greddy thermostatic block for my oil filter relocation. Hope that helps.
modulation
240sx Wannabe
Posts: 114
Joined: Fri Jun 12, 2015 4:55 pm

Re: Best engine break-in method if cams aren't new?

Post by modulation »

Thanks for the reply. Fired it up today, and of course it didn't work first try, but after fixing a few grounds, and using another car to help jump-start it fired up. Only was able to run it maybe 5 minutes at a time for maybe 20 minutes total revving it at 2-3k rpms, but it had good oil pressure, got up to temp and sounded great.

Few problems.
1. Narrow O2 sensor is probably bad, rattles when I shake it, ECU didn't see any voltage, and I tested the wiring with a volt-ohm-meter and it's good, so ordered new o2 sensor, should be able to pick up tomorrow.
2. Can't idle properly, probably need to raise idle (all idle control stuff is removed, I use throttle plane set screw.) Also need o2 sensor to work properly for it to idle.
3. Big pain in the ass is I got a big rear main seal leak, my fault for pounding it in un-evenly. Not much oil leaks when car is off, but after car is on for 5 minutes I get 1/4 cup leaking from bell housing. Removed one of the engine-trans mounts, and it's coming from above the oil pan where the dust shield is so rear main is gotta be the only thing that could be leaking.. Sucks I gotta drop the trans, but compared to rebuilding an entire engine it's not big deal right?
4. Not sure if timing is off, since I can't get it to idle I can't tell, revs great, and distributor is in almost exact same position it was in when I took it out (marked the head/dist before taking it out) but I get a bit of backfire in my intake on idle.

Man I'm so pumped though. Can't believe I'm actually a "successful" engine builder...
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