1968 Colony Park 482

[FirstEliminator]

Hi Lars,
    The crank was touching the windage tray. But, the engine still makes noise after removing the windage tray.

   Since my last posting, the Colony Park has been sitting. No driving means no risk of internal damage to a 427 block. I'm trying to muster up some motivation to get it done as Beaver Springs is 5 1/2 months away. Plenty of time....right?  Ha!, it'll get here quick!  Ugh, I just gotta get started.   Also, I'm trying to motivate a friend to get his car together by coercing him with a fresh C-6. Last year we all made it down. The only FE car brought by our group was my white and primer 64 Marauder sitting in show. Hopefully we have a few in 2020.


   Mark

[Towd56]

Get her going Mark!

[FirstEliminator]

Step one.

[FirstEliminator]

Step 2.

https://www.youtube.com/watch?v=c4_sWICkWKU


 Thoughts?

[machoneman]

Wow, that's weird! 

Maybe, get close to each piston (cardboard tube to the ear, have someone else crank her over) and see if just one is causing the squeek. Once found, remove that slug and see if the noise goes away.

Could though be a crank issue but I doubt it.

[410bruce]

Tight wrist pin?

[Bolted to Floor]

Wow, that piston rock at the end is wild. I’ve never seen anything like that. Broke ring maybe??

[blykins]

Not sure what the noise is, but it looks like you have way too much piston/cylinder clearance. 

[My427stang]

I am surprised at how much a properly fitted piston can rock when you do a test like you did, but yours does seem extreme. 

You would think you'd see some wear on the bore at the skirt location though if that was the issue.  That being said, I'd pull one piston out at a time, look close, see if you can see any tracks making the noise, or a magical disappearance of the noise when turning. If nothing looks wrong, and the noise is gone when it's just the crank and cam in there, bore gauge and micrometer, check clearances and bore shape, and recommend you do it with a head bolted on from the bottom at this point.

The snap type of noise, in the valley turning slow, makes me wonder.  I didn't have that on my flexi-445 a couple years ago, but I had all kinds of odd noises when running, and they all matched yours.  It was just too loose and too crooked.  FYI on that one, I tried to take a shortcut with a machined block, no deck plate and I knew it was on the loose side, never would have tried it if it wasn't my own engine.  Never again  LOL

[FirstEliminator]

I took a quick measurement with dial calipers. The bore measured 4.250  The skirt of one piston measured 4.245. Calipers aren't as precise as a calibrated mic. But, I gave me a bit of a comparison. What I've found for a measurement for the Mahle xxxxx4550 piston is .0041-.0049 clearance. Is this correct? 
  Only piston #1 was removed. I've been working late all week, so chances are I will probably not go back into the shop this weekend to further disassemble the shortblock.

[machoneman]

Wow, that piston rock at the end is wild. I’ve never seen anything like that. Broke ring maybe??

Yeah, after finally looking at the vid through the entire end......that very last shot of I think #8 at the end of the vid shows waaaayyyyy too much rock.

[FirstEliminator]

If the bore is right on 4.250, it sounds like the solution is a different set of pistons. My not be a bad idea as I think it needs a bit more dish.

[My427stang]

I took a quick measurement with dial calipers. The bore measured 4.250  The skirt of one piston measured 4.245. Calipers aren't as precise as a calibrated mic. But, I gave me a bit of a comparison. What I've found for a measurement for the Mahle xxxxx4550 piston is .0041-.0049 clearance. Is this correct? 
  Only piston #1 was removed. I've been working late all week, so chances are I will probably not go back into the shop this weekend to further disassemble the shortblock.

Yes, the big bore Mahles are .0041-.0049 but I personally think that is on the loose side for a 4032, best to match their numbers, although I would be leaning toward .0041 on a street build like yours.

The calipers are not adequate, period, you can't get precisely to the checking point, not even for bench racing at this point in your build.  It won't give you good numbers and even more important, there is no way for you to check the size and shape of the bore to compare the numbers to get the actual clearance without a bore gauge.  FWIW, even a freshly and properly prepped bore isn't exactly 4.250 from top to bottom and changes with the head bolted on.  Our goal is always to be as close as we can to straight, after torque, heat, and all the odd things bolted to a block, but just measuring the top of the bore tells you absolutely nothing of what is going on beneath it.

If you don't have a bore gauge and big mike, just strip it down while looking for things that look different, and if you do or don't find the exact source of the noise while doing that, still have a machine shop use a torque plate or even a head on top the bare block and measure the bores and piston that matches each bore at the checking location.  That way they can tell you bore size, taper, roundness and clearance with the pistons you have.  It will be money well spent

I know this seems preachy, and hats off to you trying to do forensic work, but the tools you are using will only confuse you with bad data.  The proper measurement, and especially with a head torqued down or torque plate, will be a few hours work at most for someone with the right tools and will rule out or convict your clearance numbers. 

[FirstEliminator]

   Off an on for about a decade,  I've been wanting to buy a dial bore gauge. Maybe now is the time. As far as dial bore gauges, is everyone dead set on a .0001" increment or is .0005" usable for this application?

   Just thinking of options, lets say the pistons are too loose in the bore. What is the course of action? Go up to the next bore size? What is the next bore size from 4.250? Or is there such a thing as pistons available in 4.250+.001 over size?

  Tomorrow after work I will get this engine the rest of the way apart. Also I will see if my big micrometer set has standards with it.  If not, MSC deliveries come next day.

[FirstEliminator]

http://www.us.mahle.com/media/usa/motorsports/fe-inverted-dome-web.jpg

    Why is it the 482 piston #930264550 calls for .0041-.0049 when the other pistons call for .0025-.0033.