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Old 11-09-2012, 07:53 PM
oldbogie oldbogie is offline
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Quote:
Originally Posted by Mertz View Post
I am putting together my 65 283 after doing the machining in my class and having the final honing and balancing done by my instructor. I have the crank, pistons and cam installed. I will have the oil pump and fuel pump installed in the next few days along with the timing chain.

I have been reading up on what break in oil to use and my instructor recommended Joe Gibbs BR which I can get locally. I have the bearings and the cam coated with moly graphite assembly lube. I want to get the heads on the valve lashed but I have read that I should not pump up the lifters. I was going to prime the pump and the engine before installing the intake manifold. On a video I have the guy primed the engine before he put on the heads and push rods. He kept pumping until no more bubbles came out of the lifters. Isn't that pumping up the lifters? Also by priming the engine am I going to be wiping of the assembly lube off the cam lobes and bearings? I won't be starting the engine for some time but I want to get it ready as much as possible.

Do you have any recommendations how far I should take this before covering it up?
Use a moly lube on the cam and lifters, I wouldn't let the engine sit for months un-run, at least put it on a test stand and run it in for half an hour at a 2000 RPM to get through the initial cam break in.

The problem with pumping up the lifters is just that, you can fill the gap between the plunger and inside bottom of the body to the point where the plunger is now pressed against the retainer clip on the top of the lifter body, you can see this. That means that you have to adjust the rocker just to where there is no lash in the push rod (((BUT))) I really want your attention!!! There can be NO adjustment made past that point (the instructions tell you to take up the lash and tighten the nut 1/2 maybe 3/4 additional turn) NO not if you pumped the lifter up. If you go beyond zero lash without the engine running there is no way for the lifter to bleed the oil that has the plunger and body hydraulically locked at their internal base clearance. Attempting to push into this zone risks bending the push rod or damaging the check valve or maybe even blowing out the bottoms of the plunger and/or the lifter body. This would be most similar to the kind of damage that can happen when you run a bolt into a blind hole that has a pool of oil at its base.

So if you know the lifters are pumped up and make a correction for that when you take up the lash just to zero or a little looser you're OK, but you then have to wait to make the final adjustment of 1/2 to 3/4 turn in beyond zero lash till the engine is running so the check valve in the lifter will be cycling and hydraulic lock up will be avoided.

When you don't pump up a new lifter (assume previously run lifters to be pumped up and treat them to no more adjustment than zero lash) when you otherwise go to zero lash with a dry lifter and then add 1/2 to 3/4 turn it sets the running clearance but the plunger is being held up from its bottom seat by a spring so it will always feel mushy if you really crank on the rocker or push rod you will feel this while making your first adjustment. This is OK! When the engine is prelubed with the valve springs pushing on the plunger the cavity under plunger will only fill to the space limit that exists depending on whether the lifter is on the heel or on a lobe. Any movement after you initially set the lash adjustment, which is done with each lifter on the heel of its cam lobe, once you rotate the still un-oil-pressurized lifter the plunger will set down onto a seat in the bottom of the body as the valve spring pushes it down and it will only fill with as much oil when pre-lubing without rotation of the crank as there is space under the seated plunger, therefore, it will not hydraulically lock. Rotating the engine cycles the lifter through the force of the valve spring this will exercise the check valve and it will fill the clearance chamber to raise the plunger till it feels valve spring pressure. This should then keep the push rod cup at the number of nut turns as that translates into clearance dimension. Given a fine threaded 3/8's bolt has 24 threads to the inch turning down 1/2 turn beyond zero lash will give a running clearance to the retainer of .0208 inch to a 3/4 turn of .0308 inch. If the lifter bleeds down to fast it won't hold this and it will tick, if it pumps up because its chasing lash added by "valve float" it will hold the valve off the seat by this amount.

Bogie
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