Thread: Priming a dry engine

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Don't overlook the obvious question:

How does the smoke get into the circuit in the first place?

Well, it's simply magic.

A wizard stands at the end of an assembly line, uttering incantations, and putting in the smoke.

The only indication of the wizard's alignment comes when the smoke gets let out. White smoke shows good, black smoke indicates evil.

Oh, and a bulb doesn't emit light, it sucks in the dark, and stores it in the battery. So you see, batteries start depleted, or empty, and you throw them away when they're full. Nicad cell discharge the dark into the power circuit of the charger.

And lots of smoke means, it was full of it..

Yeah, and it appears that some of the members here are full of it as well.....

.

HijackedThread.gif
ARRRRRGH! Avast, Matey! We're off course!

OK then back on course..

Does priming the pump wet the cam?

http://www.grumpysperformance.com/SBCOiling.gif

Yes - that's a qualified yes. In the diagram above you see that the oil is pumped through the filter to the three oil galleys above the camshaft, and follow the path the oil takes. If you keep the pressure up long enough while "priming" the engine, the oil will overflow the lifters and the pushrod tips a bit and run back down through the valley and drip onto the cam lobes. If there is a glitch in the system, it might not work as it should. I always liked to get an extra hand to keep the drill motor I was using on the priming adapter going while I slowly turned the engine over by hand, and I usually ran the priming at least two or more minutes after I saw oil at the rocker arms. My big Milwaukee drill motor would give me 40 to 50 PSI at the mechanical gauge.

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My apologies to you IowaTom...I didn't mean to hijack your thread...

Originally Posted by Rrumbler

In the diagram above you see that the oil is pumped through the filter to the three oil galleys above the camshaft, and follow the path the oil takes. If you keep the pressure up long enough while "priming" the engine, the oil will overflow the lifters and the pushrod tips a bit and run back down through the valley and drip onto the cam lobes.

I may be wrong (please correct me if I'm wrong), but I seem to remember the valley drains offset and not directly over the cam. Again I may be wrong, but I believe the cam is oiled by crank splash (unless you have bottom oiling lifters). I believe this is why it is so critical on a flat tappet cam to break the cam in at 2000+ rpm for 20 min, to ensure the oiling of the cam.
Also, on a new motor I was taught to minimize turning the motor over once the valves were set, to minimize wiping the high pressure lube installed on the cam lobes off before break in.
If you installed a new flat tappet cam and did note use high pressure lube on the lobes, I would recommend removing the cam and installing the lube on the lobes prior to start up.

Originally Posted by 36 sedan

Again I may be wrong, but I believe the cam is oiled by crank splash (unless you have bottom oiling lifters). I believe this is why it is so critical on a flat tappet cam to break the cam in at 2000+ rpm for 20 min, to ensure the oiling of the cam..

Just an "off the cuff" remark, but.. when you mention cam oiling, you need to clarify the cam journals do or may get oil from the oil pump and it is the lobes that are actually oiled by the mist of oil inside the engine caused by the 2K rpm. ( or thereabouts..) SOme folks hear one thing but aren't clear on the topic of how things happen when it comes to cam lubrication. HTH.

Thx 34-40, the lobes were what I was wondering about. I'm about to ressurect a motor which has been shelved for a decade.

I'm learning a lot from this!
When I start this engine for the first time do I bring it up to 1,500 to 2K rpm and hold it there several minutes?
I realize this might be like asking a question about what oil to use... a myriad of different answers, but I'd like to give this engine a good chance at a long life. :-)

The cam manufacturer generally specifys the requirements. It should'a come in the box.

But the generic spec is 2k rpm for 20 minutes. ymmv, imho, yada yada yada....

Originally Posted by 36 sedan

I may be wrong (please correct me if I'm wrong), but I seem to remember the valley drains offset and not directly over the cam. Again I may be wrong, but I believe the cam is oiled by crank splash (unless you have bottom oiling lifters). I believe this is why it is so critical on a flat tappet cam to break the cam in at 2000+ rpm for 20 min, to ensure the oiling of the cam.
Also, on a new motor I was taught to minimize turning the motor over once the valves were set, to minimize wiping the high pressure lube installed on the cam lobes off before break in.
If you installed a new flat tappet cam and did note use high pressure lube on the lobes, I would recommend removing the cam and installing the lube on the lobes prior to start up.

The drain back holes in the valley are between the lifter bosses on Gen I blocks (on Gen II "roller" blocks, they are different, but cam lobe oiling is not so much of an issue on a roller if good assembly techniques are followed). When the oil from static priming, eg. with a drill motor, runs down the pushrods and seeps out around the top of the lifters and the bosses, it runs back through the holes, down the lifter bosses under the web, and down the lifter body to the cam lobes. In operation, yes, the primary lubrication of the cam lobes is from splash/mist, but for pre-startup, the combination of the high pressure lube and the oil from static priming should be sufficient that the risk of galling on starting should not be a concern.

In my early wrench years, the gentleman I shadowed taught me that slowly rotating a fresh engine, while static oiling, distributed the oil around the bearings, the better to provide protection during initial start, even though the bearings had been oiled by hand during assembly, and we never talked about camshaft lubrication; it seemed it was a given, what with the assembly lube and oil that got onto the cam from priming.

Agreed, I would not install any flat tappet cam without a thorough coat of camshaft assembly lube, and I would limit the amount of rotation of the crank to only two complete turns - rotates the camshaft only once.

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Originally Posted by Rrumbler

The drain back holes in the valley are between the lifter bosses on Gen I blocks (on Gen II "roller" blocks, they are different, but cam lobe oiling is not so much of an issue on a roller if good assembly techniques are followed). When the oil from static priming, eg. with a drill motor, runs down the pushrods and seeps out around the top of the lifters and the bosses, it runs back through the holes, down the lifter bosses under the web, and down the lifter body to the cam lobes. In operation, yes, the primary lubrication of the cam lobes is from splash/mist, but for pre-startup, the combination of the high pressure lube and the oil from static priming should be sufficient that the risk of galling on starting should not be a concern.

In my early wrench years, the gentleman I shadowed taught me that slowly rotating a fresh engine, while static oiling, distributed the oil around the bearings, the better to provide protection during initial start, even though the bearings had been oiled by hand during assembly, and we never talked about camshaft lubrication; it seemed it was a given, what with the assembly lube and oil that got onto the cam from priming.

Agreed, I would not install any flat tappet cam without a thorough coat of camshaft assembly lube, and I would limit the amount of rotation of the crank to only two complete turns - rotates the camshaft only once.

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Thank you.