Author Topic: 428 piston pics  (Read 1451 times)

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plovett

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Re: 428 piston pics
« Reply #15 on: October 25, 2020, 01:57:21 PM »
A lot of particles in those pics!  I am not sure if that is just from the block being exposed or if they were already there.  Going to take a closer look.....

pl

plovett

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Re: 428 piston pics
« Reply #16 on: October 25, 2020, 02:29:03 PM »
The particles seem to be 99% leaf debris from my garage.

pl

My427stang

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Re: 428 piston pics
« Reply #17 on: October 25, 2020, 02:56:37 PM »
If they mic good no reason you can’t reuse Could coat or just let it be there for a little extra oil retention :)
---------------------------------
Ross

- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

plovett

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Re: 428 piston pics
« Reply #18 on: October 25, 2020, 03:04:12 PM »
If they mic good no reason you can’t reuse Could coat or just let it be there for a little extra oil retention :)

Whole new rotating assembly going in.  Just looking at pistons for information/learning purposes upon disassembly. 

thanks,

pl

plovett

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Re: 428 piston pics
« Reply #19 on: October 25, 2020, 03:13:25 PM »
I plan on boring the block, the minimum amount.  It is currently at 4.155".  I hope to go 4.165" if possible.  I would go 4.160" if that would work.

pl

Nightmist66

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Re: 428 piston pics
« Reply #20 on: October 25, 2020, 07:49:12 PM »
Paulie, I'm trying to get caught up on your engine. Was this teardown from the concern about the valve lash moving every now and then? I spot what looks like an unhappy cam bearing in the last couple pics. Could explain why the lash moved and why the skirts got scuffed. I also agree a sharp edge on the bottom of the bores is a likely cause as well. Hope you get it resolved.

« Last Edit: October 25, 2020, 07:57:18 PM by Nightmist66 »
Jared


66 Fairlane GT 390 .035 Over 390, Wide Ratio Top Loader, 9 inch, 4.71

cjshaker

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Re: 428 piston pics
« Reply #21 on: October 25, 2020, 10:54:53 PM »
I spot what looks like an unhappy cam bearing in the last couple pics. Could explain why the lash moved and why the skirts got scuffed.

A very unhappy cam bearing. That's a burred edge sticking out the side of it. Might have happened when pulling the cam out, but you can see the edge of the bearing is rolled over also.
Doug Smith


'69 R-code Mach 1, '65 427 MR, 2x4, 4-spd, 4.30 Locker
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1970 F-350 390
1958 Ford Ranch Wagon 390

plovett

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Re: 428 piston pics
« Reply #22 on: October 26, 2020, 04:24:11 AM »
I spot what looks like an unhappy cam bearing in the last couple pics. Could explain why the lash moved and why the skirts got scuffed.

A very unhappy cam bearing. That's a burred edge sticking out the side of it. Might have happened when pulling the cam out, but you can see the edge of the bearing is rolled over also.

I've been looking at that, too.  The cam didn't pull out easy.  I didn't think much of it at first.

pl

plovett

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Re: 428 piston pics
« Reply #23 on: October 26, 2020, 04:30:06 AM »
Paulie, I'm trying to get caught up on your engine. Was this teardown from the concern about the valve lash moving every now and then? I spot what looks like an unhappy cam bearing in the last couple pics. Could explain why the lash moved and why the skirts got scuffed. I also agree a sharp edge on the bottom of the bores is a likely cause as well. Hope you get it resolved.



The teardown is just to build a new motor.  I didn't have a specific reason other than that.  So these issues are pretty much academic other than I don't want the new motor to have the same issues. 

When I pulled the cam it didn't come easy at first.  There was some resistance and then it came easily.  I didn't think much of it at the time.  So I am not sure about the cam bearings.  It looks like something was going on there, but I might've tweaked 'em more on the way out.

pl

plovett

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Re: 428 piston pics
« Reply #24 on: October 26, 2020, 04:52:00 AM »
Well, I did have a "feeling" that I should tear this engine down, LOL!   It has always run good, leakdown was good, etc.  It's also been been run hard.  I didn't keep track of the miles, but it's less than 10K, I think.  I am glad I did tear it down now.  It might have had multiple issues.

Thanks for all the comments and insight.

paulie

pbf777

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Re: 428 piston pics
« Reply #25 on: October 27, 2020, 10:20:18 AM »
That is a clearance issue. To high up on the skirt. Mike


     Agreed, as generally a more defined parting line would exist at the stopping point the exposed piston skirting if solely a ruff edge at the bottom of the cylinder; and probably every bit as guilty is the compounding foreign particulate intrusion.       ;)

     Scott.

plovett

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Re: 428 piston pics
« Reply #26 on: October 28, 2020, 07:07:14 AM »
That is a clearance issue. To high up on the skirt. Mike


     Agreed, as generally a more defined parting line would exist at the stopping point the exposed piston skirting if solely a ruff edge at the bottom of the cylinder; and probably every bit as guilty is the compounding foreign particulate intrusion.       ;)

     Scott.

That makes sense.  Thanks.

pl

gt350hr

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Re: 428 piston pics
« Reply #27 on: October 28, 2020, 10:08:08 AM »
  Respectfully to all those that have offered up opinions , what "I" see is "debris" in the skirts , with the second ring as the probable source as it looks to be 50% or more worn. The "bottom of the bore" is often a source of mild scuffing BUT normally leaves a whitness "line" LOW on the piston as only a half inch or LESS comes out the bottom of the bore. The scratches showing go farther up the piston and are small grooves as most often associated with "foreign matter". It seems also to be limited to below the rings , leaving out coming through the carburetor because of a lack of air cleaner. The multiple narrow scratches are not consistent with clearance scuff or "black death" caused by literal melting of the skirt material that turns black and is "smeared" looking.
   "I" would look at the ends of the rings for a shiny spot that indicates the rings were butting. My opinion is from my 30 years in the aftermarket custom piston business and looking at thousands of damaged pistons for "root causes" , which I still do everyday.
   Randy

HarleyJack17

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Re: 428 piston pics
« Reply #28 on: October 28, 2020, 10:59:35 AM »
I am far from an expert but but what Randy said matches my findings on my pistons when there was metal in my oil. Motor was spotless on the build but the dizzy gear depth was wrong and sent iron through the system along with other metal material. Not nearly as bad as yours but strikingly similar and with only dyno time. Just another opinion.

gt350hr

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Re: 428 piston pics
« Reply #29 on: October 28, 2020, 12:20:50 PM »
  I'll add that the pistons are not "scrap  bin" parts as the skirts could be hit with Scotchbrite and coated to be perfectly usable. I wouldn't say that if they had "black death".