My 427/452 autopsy results are in

[AlanCasida]

I pulled the 427 apart today to see how bad it was but before I did I ran a compression check and all the cylinders checked 195-200 except #8 and it was 175. I figured that was probably where the problem was and that is where I thought I heard it knocking. Next I cut the oil filter apart and found a bunch of metal in it. When I pulled the heads you could see where the knocking was coming from, the top of the piston had a couple of good shiny spots where it had been hitting the head. When I got it out and the pan off I could see #8 rod had gotten pretty hot and when I pulled the cap off my suspicions were confirmed, I had spun the rod bearing. They had gotten thin enough that one half was laying on top of the other. It scratched it up pretty good. Hopefully it will be salvageable, we'll see. The good news is it looks like the cylinder is ok. It has some scratches but I think they'll hone out...I hope! I guess I should have went with my gut at the motel in Norman when I was running the valves. It was turning over really hard by hand and I thought something was up but I couldn't put my finger on it. It still had good oil pressure. Anyway, I have all winter to decide what I want to do.         

[cjshaker]

How does the crank and other bearings look? I've had that happen before and never could come up with a good reason why one rod bearing failed and the others looked good.

At least the problem isn't fatal to the block, and everything except the one rod should be reusable, assuming the crank is ok.

[Stangman]

Glad it’s not worse Alan. Do the bearings have the bevel on the edge on one side maybe that one was riding on the crank were it bevel up on the journal?. Not really liking the piston it looks like it was beat down a little. Does the ring feel ok in the ring land. Also not sure how it works but with that one rod seeing so much heat does that hurt it’s strength?. I think I would be more comfortable getting a new rod and piston but I would see what some of the builders think. I’m glad it’s only this stuff though. Good luck I’m sure you will keep us informed.

[jayb]

Looks fixable Alan, I'm sure you can get it back together with fairly minimal fuss.  Check the oil hole in the crank and make sure it is good between the #5 main and the #8 rod, and mag the crank too to be safe.  How does the #5 main look?

[My427stang]

If there is enough journal to turn, have it magged, just in case a crack was dumping the oil

What were your bearing clearances and what were you running for a pan? Also what was total timing on that one?

[AlanCasida]

Thanks for all the replies. I haven't dug into it deeper as of yet. It was late last night when I got to the rod.  This is the new Scat crank I put in last year after torque converter issue ruined my OEM crank. I had it all rebalanced at Gessford Machine and I am pretty sure they magged it while it was there. They are pretty thorough. As far as clearances I don't remember for sure but I think it was .002" or maybe .0015". I am thinking it might have been on the tight side but my memory isn't what it used to be. I really need to take notes when I do stuff like this. I am running a Canton rear sump pan that only holds 6 quarts and that has been a concern of mine for awhile. I had even been considering adding a "T" to the sump to give it more capacity. I was running 32 deg total timing. I got to thinking this may have started even before I left. On one of my shake down drives I noticed the oil pressure gauge fluctuating a bunch +- 20 psi and I had to drive it maybe 15-20 before I could get to a place that had oil. I think it was sucking the sump low enough to make the pump cavitate.   

[wowens]

My 2 cents. The piston to the left looks awfully clean on the quench area. It's down in the hole and it's dark in the hole so hard to tell. You may not have enough quench clearance. A light touch may have crushed the bearing resuting in the final damage.
I would look very closely at piston to head clearance on all the pistons. Especially on that corner of the block.

[AlanCasida]

My 2 cents. The piston to the left looks awfully clean on the quench area. It's down in the hole and it's dark in the hole so hard to tell. You may not have enough quench clearance. A light touch may have crushed the bearing resuting in the final damage.
I would look very closely at piston to head clearance on all the pistons. Especially on that corner of the block.

Well when I saw that I got to thinking I did go with some .027" head gaskets to gain a little compression. That may not have been a good move on my part.

[frnkeore]

Had you measured the deck clearance, before ordering the .027 gaskets? If so, what was it?

[AlanCasida]

Had you measured the deck clearance, before ordering the .027 gaskets? If so, what was it?

I did a quick measurement with my dial calipers and it looks like .010" in the hole.

[frnkeore]

If accurate, that's .037 and that's right on the raged edge.

I would remeasure the other holes for deck clearance, with a depth mic and see what you get.

[My427stang]

Good to check, but that kissed one is likely due to the bearing.  .037 should live but it starts getting tight and you don’t want to be guessing

[Hemi Joel]

The rule of thumb for FE's with stock style pans is to always fill it, then add an extra quart before making any drag strip passes. You could have run the pan dry, I know of a few instances where that has happened.
If your bearing clearance is on the loose side, only you will know it. If your clearance is on the tight side, everybody will know it. I usually shoot for 003 to .0035 on the rods and use h series bearings that give more clearance at the parting lines.
Good luck finding the cause and getting it all fixed, Alan

[My427stang]

Thanks for all the replies. I haven't dug into it deeper as of yet. It was late last night when I got to the rod. This is the new Scat crank I put in last year after torque converter issue ruined my OEM crank. I had it all rebalanced at Gessford Machine and I am pretty sure they magged it while it was there. They are pretty thorough. As far as clearances I don't remember for sure but I think it was .002" or maybe .0015". I am thinking it might have been on the tight side but my memory isn't what it used to be. I really need to take notes when I do stuff like this. I am running a Canton rear sump pan that only holds 6 quarts and that has been a concern of mine for awhile. I had even been considering adding a "T" to the sump to give it more capacity. I was running 32 deg total timing. I got to thinking this may have started even before I left. On one of my shake down drives I noticed the oil pressure gauge fluctuating a bunch +- 20 psi and I had to drive it maybe 15-20 before I could get to a place that had oil. I think it was sucking the sump low enough to make the pump cavitate.   

I doubt anyone magged a new crank if you didn't ask.  However, you can't assume anything now, even though I suspect that crank is junk

I'd be very leery to run an FE journal at .0035, pretty loose for anything but maybe race only, cold start can hammer the top bearing a little over time if too loose. if that applies to you,  but the oil supply is certainly good advice.   I like .001 X rod journal, round up, especially for something on the street.  So in this case,  .0025 is what I'd be shooting for up to .003 if the parts forced me there.  FWIW I haven't seen a tight SCAT FE crank yet either, on the 2.20 stuff I generally need .001 or a mix, haven't run a SCAT FE journal though. 

Of course restricting helps keep a little more oil in the pan too

My gut says, still tranny/converter problem combined with maybe kissing the heads based on the marks on the adjacent cylinder, but who knows, could have taken out a second bearing, just not spun yet.

Sounds like you have a strong running combo, just needs some careful measuring on the next version to get it to stay together

Where are you from Alan that you use Gessford?  They aren't close to me in Omaha, but closer than most others, I use a single local guy that holds numbers better than anyone I know, but you pay for it.  If he drops from overwork, I am hurting LOL

[67xr7cat]

Sorry for your bad luck.

From your two threads I see three issues that likely caused the failures:

1. Ran low on oil. No. 8 last in line so makes sense. I'd get a better pan on there and make sure mark the dipstick once you figure out the right level.

2. Rod clearance is too tight. .0025 - .0028 be a good clearance.

3. Get rid of that converter. Pull and check the front pump and input makes sure all is good.

If you are still running the oil relief at the back of the engine I'd check make sure it is working right. Pumpbuilder sells a new spring and valve.

Good luck, Steve