My Hemi Is Pinching Plugs Closed...Help Needed!

My only guess is that it came from one of the cheap ass air cleaners. I have had to fix the two center ones a bunch of times. Who knows? And no, I didn't find the nut sitting on top of the head.... I just put it there for the pic. Im taking the head to the machine shop today, and go from there. As far as the piston goes, in a perfect world I would replace it. They were custom made by Ross, and as far as I know, they won't just make you one. I am way too broke, and way too short on time to replace all of them. Im just gonna clean it up as best I can and run it. I know it will at least get me to the roundup....

 

Is the piston cast or forged? I really don't think the piston is trash because I've had this happen once also and the piston was fine but hey you never know!
Good luck on getting it going again as soon as possible.

 

Thanks man.... the piston is forged.

 

I spit an exhaust valve out of the engine in my dirt car and it did a number on the piston, a .060 over J&E for a 331 which is not a cheap piece. I pulled it out and had it crack-checked, and it had no structural problems. I did take it to a very skilled welder who welded up the gouges in the head of the piston, and then ground it down to it's original shape and finish. That was a few years ago and the engine has run strong since. Single pistons were not available, so that was my only choice, and it worked. I would go to the trouble of pulling it and double checking everything to eliminate the probability of problems down the road. From my experience, it looks like you lucked out.

 

You're probably OK with the piston, Ross makes some tough hardware. I don't see any real deep pits, looks like the edge of the piston in the valve reliefs has the worst damage. Pull it out and polish off as many of the sharp edges as you can. Take a good look at the top half of the connecting rod bearing as well.

 

Yeah, I agree. If it's forged you're probably fine.

As for Ross, if you still have the paperwork associated with the pistons (they usually come with a quality check list showing weight of each piston, specs., etc.) there is probably a reference number to your order. I believe they keep your order on file for quite awhile, and I think they will make you one piston if you REALLY had to. But it will obviously cost you. You're probably okay, though.

I also agree with Ebb. Probably a good idea to pull it off and do a good inspection as well as knock down anything that may do harm.

 

Just had the same thing happen to a buddies O/T 1967 GT500 the jamb nut for one of the aircleaner studs was the culprate - the offending cylinders plug was destroyed too - your lucky - we had to sleeve his cylinder (and completely rebuild the 428) as it cracked the wall in three places!

 

The pics tell me that the nut bounced freely and was not crushed between piston and 'whatever' so structural damage to the piston is likely non-existant.
I would clean off the piston top as best you can without removing too much material...a buffing wheel might be enough... and the same with the combustion chamber only there you will need something like a flapper wheel. Just get rid of all of the 'points' that can get hot and cause pre-ignition. Yes, carbon build-up will be an issue with all of the pockets.

.

 

I agree with the majority opinion ... the piston looks to me like it's probably fine. I wouldn't really want to take the bottom end apart just to check it unless I absolutely needed to be sure. But I would like to clean up the top a little. Bead blasting might be good, but you can't really do that with the thing in the motor. I would certainly button up everything tight to keep grit out of the motor, no matter what method I used.

 

Dude, I think it's no good now. You need to build a new Hotrod. I'll come get it so you won't have the hassle of getting it out of your way

Realy, I agree with those above. Buff it off and put it back together with a new valve. You'll never know it happened.

 

Hurry up. Side by side donuts.

 

And that, ladies and gentlemen, is why you come off the wallet for a few hundred bucks to pop for an $800 set of forged pistons over a $400 set of cast slugs for our vintage motors.

There's a very real chance that would have shattered the dome on a cast piston, at which point the con rod becomes a battering ram that slams through the cylinder wall and out the side of the block. If it's REALLY feeling froggy, it'll break the crank on the way out.

I'm really happy for you that this damage is so slight.

At the very least, I would pull the piston and file down all the high spots on the divots--they'll become hot spots and can cause detonation.

I'd also call Ross... they're a race piston company... they're used to making one or two or four pistons for racers that do exactly what you just did.
You may find out they will only sell a set of 8. But you might also find out they'll do one for you. Either way, the phone call is cheap.

Congrats on dodging a bullet, and kudos for stepping up during the build and buying the insurance of forged slugs.
-Brad

 

Glad you found the issue and its not a minor thing but then could have been worse.Good luck,magic words for a Hemi are zoom,zoom before start up.......YG

 

LMAO. Funny ass shit.

 

to be safe, i think the piston needs to be checked to make sure the top ring moves feely in the ring groove

 

x2. And if that had been a hyperutectic the bottom end would now fit loosely in a 5 gallon bucket.

 

Dropped the head off at the machine shop today. Thanks you guys for the moral and mental support. Definitely could have been worse! Ill update you on monday when I hear back.

 

Send me a PM, and Ill tell you the address to send the car hauler to....

 

-----------------
Back around 1974, a buddy of mine - also
currently now on the HAMB - but who for
the sake of brevity, shall remain nameless
(but you know who you are. "BL"!) - was
campaigning an NHRA-legal Super/Stock
250hp/327 '65 Corvette. He had replaced
the stock cast iron four-hole closed-plenum
intake manifold with an Edelbrock 'Tarantula'
(the hot Super/Stock 'trick of the day' back
then!) open plenum intake, but per class
rules, instead of a Holley carb usually used
with these manifolds, he had to use it with
the original 250hp-spec 4GC Rochester carb.
Unlike Holley carbs though, which would be
perfectly safe on an open-plenum intake,
4GC Rochesters have a large, single, 7/16
inch-or-so diameter machine screw in the
center of the baseplate, to attach it to the
main body of the carb. With the stock 4-hole,
dual-plane, divided-plenum intake, if the
machine screw comes lose, it would simply
butt up against the divider in the center of
the stock intake manifold and it couldn't fall
into the engine. Not so with an open-plenum,
single plane manifold design like the Tarantula
though. And sure enough, that's exactly what
happened too! He had staged the car and
was sitting on the starting line, holding the
revs at 8500 rpm as the tree flashed down.
Then all of a sudden, just about the same
time as the green flashed on, the machine
screw in the carb baseplate came loose,
dropped down into the intake manifold and
got sucked into an intake port and "KABOOM!!!"
In about half of a nano-second, a fresh,
$5000 (a LOT of money for an engine back in
1974!) Super-Stock race engine was reduced
to 'instant, ready to eat', shrapnel and a
smoldering pile of broken parts!!! I think
he was able to salvage the carb & intake. one
cylinder head and 5 or 6 pistons from the
carnage. Everything else in the engine was
trashed!

Mart3406
==============

 

You can buy copper washers in different sizes for under the plugs.

I used to use them all the time for turning the spark plug electrode so that the open end was in just the right position for firing.

Hope that helps. Jimbo

 

over rev can stretch a rod.. just a bad thought ....

 

That went about as good as something bad can go.

 

Huh? Keep your bad thoughts away man.....

 

hey Mark,
glad your getting this figured out.
Thanks again for the ride to the Revolution!

 

I had a valve seat come loose on my '46 Knucklehead and it broke up and did a number like that on the piston and head. I had the seat repaired and ran that piston for YEARS. I replaced a blown head gasket years later and noticed carbon had conveniently resurfaced the top.

 

Hey Joe, good to hear from you. Now we know what happened on the way there..haha

 

Thanks. It's nice to be appreciated.

For an extra bonus, you guys, if you are ever in this predicament you can remove the object from the cylinder easily. Take the spark plug out, stick the air hose in the hole and blast away. The air will blow the object out the spark plug hole (if it is small enough and it usually is). This works best if you do it before you start the motor.

 

Mark, It's an extra days work, but I would pull that piston/rod and check to make sure the rings are free, check your rod for straightness and see what your bearing looks like.
It will be worth the piece of mind...
Hans

 

Any updates?