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What's the best practice to prime motor a newly built motor?

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Wanted to get everyone's opinion on the best practice to prime the motor after being newly built. I know about priming the oil pump while building the motor. I have new GSC cams as well and I was told that the first start is critical.
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If you used a good assembly lube, just start the engine. At idle you'll get oil pressure much faster.


I just started my ej257 and rebuilt heads. After turning the key to On for ten seconds a few times, I just went to start, the engine started just like it dose every day. 3 cranks and idle.


Some will say to pull the spark plugs, pull the fuel pump fuse, crank the engine for 30 seconds to a minute, or until you see oil pressure if you have a gauge installed.

305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD).  CHECK your oil, these cars use it.


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This statement would force me to call GSC and confirm what they mean by proper break in.


Proper break in and running high zinc oil is a must on flat tappet engines.


Probably idle for a few min after the motor heats up... But how long till you can load it up and drive??? Curious what they say.

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The Subarus I've rebuilt got Royal Purple break-in oil. Once primed, I'd let them run for 20-30 mins at idle only. Then, drain and refill again with the break in oil. Change at 500 miles and 1,500 miles. Dyno oil at the 1,500 mark for 3k then after, synthetic can be used.
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  • 4 months later...

So if you hold the throttle pedal wide open on start up it will crank but not fire. I believe this tells the computer to cut fuel. Pretty sure this is what you would find in the factor service manua for engine priming proceduresl. This will circulate oil without the load created during combustion.


Definitely make sure you are WOT though if you go this route. Wouldn’t want to be partial throttle and rev the hell out of a brand new engine on first start up.


But yes, make sure you have used a good bearing lube if you were down to the main or rod bearings, and a good assembly lube otherwise. Probably too late for that if you didn’t already though

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