Author Topic: Anyone see the clue to engine failure?  (Read 1079 times)

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My427stang

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Anyone see the clue to engine failure?
« on: September 14, 2024, 02:54:01 PM »
Brent can't answer, we already talked and he saw it right away

So I bought a Cobra with a blown 496 Genesis block, Stage 3 Performer RPM, solid roller, tunnel wedge...blown in the bad way not the good ways :)

Dropped an intake valve on #6, and beat up number two as well, however, #7 could not have been long for this world either...can you see why?

This is #7 and #8
---------------------------------
Ross
Bullock's Power Service, LLC
- 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

DuckRyder

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Re: Anyone see the clue to engine failure?
« Reply #1 on: September 14, 2024, 02:59:01 PM »
Valves hitting pistons?
Robert

shady

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Re: Anyone see the clue to engine failure?
« Reply #2 on: September 14, 2024, 03:06:14 PM »
piston kissing the head.
What goes fast doesn't go fast long'
What goes fast takes your money with it.
So I'm slow & broke, what went wrong?
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427FeWedge

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Re: Anyone see the clue to engine failure?
« Reply #3 on: September 14, 2024, 03:16:31 PM »
Number 6 and 7 piston swapped?

My427stang

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Re: Anyone see the clue to engine failure?
« Reply #4 on: September 14, 2024, 03:23:03 PM »
Number 6 and 7 piston swapped?

Sort of, FOUR were in the wrong place.  6/7 were both wrong and two on the other side.  Poor thing didn't have a chance.
---------------------------------
Ross
Bullock's Power Service, LLC
- 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

oldiron.fe

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Re: Anyone see the clue to engine failure?
« Reply #5 on: September 15, 2024, 10:03:43 AM »
          while it isnt nice to point fingers---if person assembled this motor can remain unknown hard /priced lesson--- shop i would note for others to avoid this costly mistake hard to see the expence of good parts destroyed by assy. errors like occurred---  oldiron--john
66' Fairlanes 427 (08/26/67- present)
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Heo

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Re: Anyone see the clue to engine failure?
« Reply #6 on: September 15, 2024, 10:15:19 AM »
Pistons mounted like it was a sbc  with center exaust valves side by side.... ???
built by a SBC builder? old habits die hard



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Stangman

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Re: Anyone see the clue to engine failure?
« Reply #7 on: September 15, 2024, 10:39:54 AM »
It doesn’t look like a new build I wonder how long it was running like that. I guess maybe unless you were really hammering it it was ok??.

cjshaker

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Re: Anyone see the clue to engine failure?
« Reply #8 on: September 15, 2024, 01:30:08 PM »
It doesn’t look like a new build I wonder how long it was running like that. I guess maybe unless you were really hammering it it was ok??.

Same here. It's clear that it's been running for a while. Is that slight scratch on #7 piston a contact point? Cam must have had a mild lift or there would be more obvious indications of contact, as well as bent valves on the offending cylinders.
« Last Edit: September 15, 2024, 01:33:28 PM by cjshaker »
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Tommy-T

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Re: Anyone see the clue to engine failure?
« Reply #9 on: September 15, 2024, 01:39:23 PM »
I made the same mistake assembling my first 427. It was a 454 inch Hi Riser with Arias small dome pistons. I didn't realize there were 4 "rights" and 4 "left" pistons. I did find out in short order when I started to check piston to valve clearance. Rookie mistake if it's your first time using custom pistons.
I also learned how much it sucked to remove double spirolocks  in that same exercise.
2 things
1) Either your roller cam ain't that big or the pistons are down in the hole. Looks like the valve just barely nicks the #7 piston.
2) Why are the valve reliefs so clean on #8 slug?

Hope the carnage isn't that bad. How about a pic of the cylinder with the dropped valve?
« Last Edit: September 15, 2024, 01:41:56 PM by Tommy-T »

My427stang

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Re: Anyone see the clue to engine failure?
« Reply #10 on: September 15, 2024, 01:57:19 PM »
Oh it hurt itself, I just didn't hang the pics.

I have no idea how long it ran, but it ran
---------------------------------
Ross
Bullock's Power Service, LLC
- 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

My427stang

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Re: Anyone see the clue to engine failure?
« Reply #11 on: September 16, 2024, 10:25:48 AM »
          while it isnt nice to point fingers---if person assembled this motor can remain unknown hard /priced lesson--- shop i would note for others to avoid this costly mistake hard to see the expence of good parts destroyed by assy. errors like occurred---  oldiron--john

If the prior owner bult it, he has since passed, no need to share names.  If he paid someone, we don't know who.

The rest of the engine, to include pushrods, rockers, rod bearings, all are in real nice shape, which tells me they were hitting very lightly and fatigued a valve stem, couldn't have been slamming, although it probably didn't run well either. Whether it could have been heard in an almost open header Cobra, who knows?  With modern pistons there is often incredible vertical valve clearance, so it may have been right at the edge, even with radial clearance being known to be bad.  Needless to say I have no desire to reassemble incorrectly to see what we already know.

FWIW - The build used Diamond pistons, Eagle H-beams, and I assume an Eagle crank but I haven't got it out yet.  It also used Clevite standard rod bearings, not narrowed, which is not standard builder fare although they looked good, even the one that ate a valve. 
---------------------------------
Ross
Bullock's Power Service, LLC
- 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