FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: My427stang on September 14, 2024, 02:54:01 PM
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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
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Valves hitting pistons?
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piston kissing the head.
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Number 6 and 7 piston swapped?
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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.
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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
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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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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??.
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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.
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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?
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Oh it hurt itself, I just didn't hang the pics.
I have no idea how long it ran, but it ran
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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.