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I don't know it all and never will. I learn something new everyday and respect those who know more than me.
Agreed, that's the attitude I try to take towards my mustang addiction and life in general.

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Not to argue but the cushion of stored oil is a hydraulic lock that resists "immediate" bleed off. Hence my comment of no bent pushrods. A short rocker slot would hammer rather than cushion no? .... Flattening the cam? Pushrod flex negates that in a marginal bind situation.
Not an argument, just a discussion. I agree that the lifter doesn't bleed off its reserve immediately but it does provide some cushion. It's not a hydraulic lock but a variable volume reservoir that can bleed off when the pressure internally exceeds the incoming, or external, pressure. This would be more pronounced in jarring situations, hence the next counterpoint.

A short rocker slot does hammer, and flex happens in more than just the pushrod. The immediate side load can cause the rocker stud to flex as well providing deflection in the valvetrain increasing the loss of intended geometry. Between the pushrod, rocker stud, and hydraulic lifter a loss of lift can take place without all of that energy going into the camshaft itself and the oil wedge that keeps it away from the bearing. And that's not taking into account the harmonics involved throughout the rpm range.

Having said all that I still am inclined to believe nothing else is wrong other than the chain having been too tight. My guess is the direct and mechanical interaction between the two didn't allow the oil wedge to form around the entire circumference of the cam journal. It's only a guess. That's just for the record; not trying to be argumentative.

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Mentioned early on was that the push rods were 1/8" longer than stock. This will tip the rocker arm over more. In such a scenario it is wise to check the slot-to-rocker stud clearance. The damage this engine suffered is unusual and warrants checking everything. True cause could be unrelated to anything so far discussed. Bringing up alternative possibilities and discussion is intended to be helpful, even if wrong. If and when the solution is found, we all benefit from the experience.
 

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Discussion Starter #85
I am close to breaking the “new” motor again. It has been a while as we were in Europe for vacation. I don’t have any questions, just closing the loop on some things.

I posted my bearing clearances in post #52. They are on the loose side so I expect my oil pressure will be lower than others. That is fine as that is how a positive displacement pump work, same RPM, less resistance, less pressure.

Again to recap, my original timing chain was way too tight with definite tension between crank and cam which ate the soft cam bearings. New chain is installed and feels “loose”. This is a good thing. Deflection is about ¼”, See pic.

I have also finished the top end and found the following which indicate there is no valve train binding as I knew but still needed to confirm. This build is very mild and never was intended to push any clearance/lift limits.

Cam Lobes – All were measured and are correct

Valve Springs – I used solid lifters in #1I and #1E. Valve spring height at full lift was ~1.41” Intake and ~1.38” exhaust. Coil bind is published at 1.13” See pics…Plenty of space left on the springs

Rocker to stud clearance – There is no evidence of rocker arm to rocker stud contact (no witness marks). Also I verified at full lift that there is ~3/32” space between the two on the front (see pic). The rear has tons of clearance.

Piston to valve clearance – Did this again with solid lifters. I have .243” clearance Intake and .279” Exhaust.

So the bottom line is there is no valve train interference, but all of these things should have been checked (and not assumed from the specs) the first time.

Now I need to find a couple days to install and break it in.

z Ready.JPG

zTiming Chain new.JPG

zvalve train 3.JPG

zvalve train 2.jpg

zvalve train 1.JPG
 

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I went out and took the bag off my original 289 with 300 miles on the rebuild and took a picture. Looks like a 1/4" to 3/8" deflection so I think your good to go. Good luck!
 

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Discussion Starter #87
I went out and took the bag off my original 289 with 300 miles on the rebuild and took a picture. Looks like a 1/4" to 3/8" deflection so I think your good to go. Good luck!
Thank you for the pic. I have no worries as I doubt with my car it will ever wear out a timing chain!
 

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Discussion Starter #88
Just wanted to close the loop. I did break in the newly rebuilt motor several weeks ago and it went just fine. I have not inspected the cam bearings (nor do I intend to) but have no doubt that they are fine. If I pull the oil pan down the road, I'll see what I can see which wont be too much). The original timing chain was way too tight and that was the problem. Break in oil was "clean" upon inspection.

Moving on to first drive in a couple weeks.
 

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Just wanted to close the loop. I did break in the newly rebuilt motor several weeks ago and it went just fine. I have not inspected the cam bearings (nor do I intend to) but have no doubt that they are fine. If I pull the oil pan down the road, I'll see what I can see which wont be too much). The original timing chain was way too tight and that was the problem. Break in oil was "clean" upon inspection.

Moving on to first drive in a couple weeks.
That’s a great result. Thanks for the closeout post, it’s always good to hear of a happy ending. I’ve learned another point to check when building up an engine.

Looking forward to reading about your successful first drive soon!
 
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