[Va68goat]

mgarblik,
I heard Paul said it collapsed .04 and I heard him say .036 when he was on the phone with someone. I do commend Paul for flying out here and addressing this problem and Jeff for flying him out here. I'm sure it wasn't cheap and I did my part by having him stay at my house to save them some expense. No doubt that mistakes happen and I said that early on but I wasn't getting anywhere with that. I'm sure it wasn't easy for Paul to stay at my house with the bantering that we had months ago. I welcomed him here and it was actually great getting to know him. I most likely should have been upfront with the dyno failure on this thread but I was really trying not to hurt the guy or his business.

I can say this, the motor is INSANE!!! The carburetor is awesome. No doubt they produce a great product. Things just got a little crazy and I hope all of this will get worked out. It will be done off this thread though!

[shoebox1.1]

If there were a in car video of the power I think everyone would like to see! Wink wink!! Lol

Badass car btw! Beautiful

[Va68goat]

shoebox1.1,
I got your hint! I'll get that done!!

[grivera]

I’m sure they are full floating rods

[NeighborsComplaint]

See my post #802 7/27/2019 - I called it the moment I heard your vid.

Glad you got it resolved.

[ponjohn]

Originally Posted by mgarblik

A collapsed piston skirt is a situation where the lower part of the piston, (skirt) crushes in toward itself in operation. From here, it gets rather complicated. The tendency for a skirt to collapse depends on a huge number of factors. Here are a few: 1. piston material 2. piston head design 3. piston skirt design 4. piston pin box design and support 5. cam grind on the skirt 6. piston skirt strut support and design. 7. oil drainback design in the oil ring groove 8. piston to wall clearance 9. amount of piston skirt that comes out the bottom of bore at BDC 10. piston to rod ratio 11. dwell time at TDC 12. detonation 13. mechanical interference 14. Dozens of other factors.

So it's a complicated series of compromises that go into piston design, machining clearances , and material choice, and application that determine the final outcome.

Thank you. To clarify.



Is it a force at the bottom of the skirt as shown in my picture?

OR a reduction in diameter or both?

[mgarblik]

Again, I am most happy that the engine is repaired, in the car and doing what a Pontiac is supposed to do. Tearing the tires off in a smoky cloud is what I mean. If in fact the piston skirt was collapsed .036"-.040", that would make for a noisy engine that would be there all the time. I have removed forged pistons with severe heat damage and detonation damage that had .008"-.010" of skirt collapse, but that's the worst I have experienced. Probably as mentioned, mechanical interference at TDC when the piston is in the crossover mode would put huge load on the bottom of the skirts and collapse them. Some on this thread "can't believe" something like this could be missed once, let alone twice. This is my guess of exactly how this could happen. New pistons come in, they are measured because we never believe what the box says. They are assigned a hole in the engine they will be installed in and probably the block is select honed to fit each piston to a hole. They typically would never be measured again. Where does this skirt collapse occur? It's not nearly as dramatic as it sounds. We all understand that the pistons are tapered top to bottom and the largest diameter is at the bottom tip. They are cam ground to have minimal metal to metal contact with the cylinder wall to reduce friction and wear. So we are looking at two little tabs at the bottom of the skirt that stabilize the piston in the bore, extremely important at the crossover between TDC and BDC. Ross pistons, in particular, have very small, thin, skirt tabs. If the tabs get bent inward, (skirt collapse) it is generally not visible by any type of inspection other than a remeasure of the skirt. Since piston slap was not considered a cause of this noise by the builder because he built-in the correct piston to wall clearance, then it can be missed on inspection. All I am saying is it can happen and this may be how it happened. We all make mistakes. The builder didn't run away from this one like many would have. This engine could have been held-up, not running for another three or four years while the situation slowly wound it's way through the court system. The car owner could have lost even more time and enjoyment of the car while lawyers delayed and finally ended up taking 50% of some small settlement. Really glad that doesn't appear to be the way this is going. Again, I repeat my offer to help make the OP whole on this deal. BTW, I am no shill for Mr. Carter. Our only personal contact has been a few minutes of conversation at the PRI show a dozen years ago. His many posts on here show me he knows exactly what he is doing and I actually feel bad for everyone involved.

[mgarblik]

Originally Posted by ponjohn

Thank you. To clarify.



Is it a force at the bottom of the skirt as shown in my picture?

OR a reduction in diameter or both?

Yes to answer your question but your picture isn't good to compare. Look at post #1367 at a Ross forged piston. Only the little "tongue" sticking down reflects the minimum piston to wall clearance. There is a gradual taper from that tip to the bottom of the ring groove. The BME forged pistons we use in our race engine have almost .006" taper in the skirt because noise is the last thing we are worrying about. Not sure about Ross. Probably around .003" or so. But those little tips are the largest diameter on a piston. If they collapse, more of the skirt contacts the walls and the piston becomes unstable, especially when it changes direction and knock results. If it's very slight when cold, as the pistons warm up, the clearance goes away in a controlled expansion and the engine gets quiet. Cast pistons fit much tighter, typically .002" clearance, have little skirt taper and thus are very quiet. But they are weak and brittle in a performance application.

[NeighborsComplaint]

Originally Posted by dataway

I want my prize ... I think I was right 10,000 posts ago.

Yeah. You hit it right out of the park. lol

Originally Posted by dataway

Yep ... that sounds random ... not a crank/rod/piston/wrist pin ... it sounds random. Certainly does sound like something hitting the oil pan to me. Doesn't not sound like the solid impact of important parts against important parts.

I still say .... Go Fund Me to send it back if necessary. Jeez, we are all in this together, YOU, Paul, all of us in my opinion .... I'd be happy to contribute. Paul has provided reams of very valuable information to this forum and it would be small pay back to contribute a few bucks to hear his opinion after getting his hands on this engine again.

[Va68goat]

Well this isn't a dramatic video but you have to remember, I havent driven a car with this kind of power before and the last thing I want to do is put it in a ditch after waiting two years. To me, this power is just insane and I have a great deal of respect for the power. I'll get better with time behind the wheel.

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


mgarblik
I agree with 100% of what you said. Paul and Jeff made made this motor right. The rest is just business. I'm so damn pumped to finally get behind the wheel.

[Colin70TA]

Ill chip in $20, somebody set something up. It sucks when stuff like this happens, I am going though it right now with my new build, its back out of the car and my original motor is back in so I can salvage a bit of what's left of the year.
I think Jeff and Paul did more then any shop I have ever come across has ever done. Might be because it was public but either way happy to see this resolved.
Go buy some tire stock and have some fun!!

Sent from my SM-A530W using Tapatalk

[shoebox1.1]

Sounds great. Looks like it pulls hard

[NeighborsComplaint]

Nice to hear it pullin' hard!

[dataway]

Originally Posted by NeighborsComplaint

Yeah. You hit it right out of the park. lol

Dang internet and all that pesky evidence of what someone said.

Actually I thought it was the oil pump drive shaft hitting something.

I'm a millennial ..... I still want a prize!!

And yes, I'd be in for a $20 donation just in the hopes that all parties go home reasonably happy. And .... jeez, the thread was worth it.

[Va68goat]

dataway, Colin70TA & mgarblik,

Thank you very much for the offer to make a donation but thats not necessary. I really do appreciate that. It's when you hear things like that, makes you realize the camaraderie between "car guys". I imagine there have been plenty of guys that have been stumped while diagnosing their motor and you guys can relate. I met a lot guys from the forum and spoke to many over the phone that are now friends.

[68 461 Bird]

Originally Posted by mgarblik

Again, I am most happy that the engine is repaired, in the car and doing what a Pontiac is supposed to do. Tearing the tires off in a smoky cloud is what I mean. If in fact the piston skirt was collapsed .036"-.040", that would make for a noisy engine that would be there all the time. I have removed forged pistons with severe heat damage and detonation damage that had .008"-.010" of skirt collapse, but that's the worst I have experienced. Probably as mentioned, mechanical interference at TDC when the piston is in the crossover mode would put huge load on the bottom of the skirts and collapse them. Some on this thread "can't believe" something like this could be missed once, let alone twice. This is my guess of exactly how this could happen. New pistons come in, they are measured because we never believe what the box says. They are assigned a hole in the engine they will be installed in and probably the block is select honed to fit each piston to a hole. They typically would never be measured again. Where does this skirt collapse occur? It's not nearly as dramatic as it sounds. We all understand that the pistons are tapered top to bottom and the largest diameter is at the bottom tip. They are cam ground to have minimal metal to metal contact with the cylinder wall to reduce friction and wear. So we are looking at two little tabs at the bottom of the skirt that stabilize the piston in the bore, extremely important at the crossover between TDC and BDC. Ross pistons, in particular, have very small, thin, skirt tabs. If the tabs get bent inward, (skirt collapse) it is generally not visible by any type of inspection other than a remeasure of the skirt. Since piston slap was not considered a cause of this noise by the builder because he built-in the correct piston to wall clearance, then it can be missed on inspection. All I am saying is it can happen and this may be how it happened. We all make mistakes. The builder didn't run away from this one like many would have. This engine could have been held-up, not running for another three or four years while the situation slowly wound it's way through the court system. The car owner could have lost even more time and enjoyment of the car while lawyers delayed and finally ended up taking 50% of some small settlement. Really glad that doesn't appear to be the way this is going. Again, I repeat my offer to help make the OP whole on this deal. BTW, I am no shill for Mr. Carter. Our only personal contact has been a few minutes of conversation at the PRI show a dozen years ago. His many posts on here show me he knows exactly what he is doing and I actually feel bad for everyone involved.

I don't see it quite like you do but I do agree with your opening statement and I am also happy this is resolved and Joe is driving and enjoying his GTO like he should have been able to do a long time ago.
As I see it Paul made two mistakes here, 1st with the oil pump and second with the repair. When he replaced the rod on the #5 piston, he should have noticed the damage on the piston and took measurements there. Extra care should have been taken with this engine since Joe's friends convinced him to send the engine all the way across country to Paul who was highly recommended. He could have taken it to other reputable Pontiac engine builders on the east coast but he went with Paul. I came across this thread a few months ago and Paul was blaming it on bad gas. I have been around the Pontiac hobby for almost 40 years and I knew it was internal.
I also believe with this story being aired on this forum it put pressure on Paul to make it right. Without social media, I would expect the typical engine builder response you mentioned above and blame the customer. Times have changed and social media is now a factor . Paul did admit he made a mistake on the oil pump and he should own up to the fact he missed the damaged piston and pay the $2,575 and the additional $1,900 chasing the knock. He also should have worked it out an amount with Joe before leaving his home, I would have..
I also have never met Joe and never heard of Paul until this thread so my opinion is not biased either way either. Joe paid out an additional $4,500 he shouldn't have. I hope he is compensated to his satisfaction, time he lost he can never get back. my2 cents.

[shoebox1.1]

I agree... now let’s start another oil thread and see some drama there! Lol j/k. Yeah it’s a bad deal due to the long distance thing. I think they’ll make it right. Hopefully the car sees some fun at track before the winter Hibernation!

[Va68goat]

shoebox1.1,
I'm pretty confident that all will end well. The "oil thread"..hahaha. I started reading some of those threads and developed a headache. As for the track, I think thats a long time away. I'm new to these old cars. I'm going to need some drive time before I even consider that..hahaha.

[NeighborsComplaint]

I'm also going to "throw down" and a claim a double diagnostic victory.

Way back I suggested oil pump pickup/oil pan interference as a possible cause of the noise. I also mentioned that my 66 year old eyes noted marks in the bottom of the pan that witnessed this interference.

Low and behold, it was later revealed the oil pump pickup had fallen off and was laying in the bottom of the pan. I guess that would be considered pump pickup/oil pan interference. lol

Not a cause of the noise on your motor but obvious to my eye that the pickup rubbed the bottom of the oil pan.

[gtofreek]

I just have a few things to say about this.

Everything being offered against me is strictly speculation on all Joe's friends part. Don't get me wrong, I have respect for those guys, I met them and they seem very knowledgeable, and I like them. BUT none of them were here at our shop or took part in any of this build. They came along after the fact so everything they say is simply their opinions. They question whether I even took the engine apart. That's ridiculous. I took this engine completely down. Even took all the pistons off the rods to make sure there were no issues with the pins or pin bushings. I even posted pictures on here of the rods and crank. I didn't want any more problems with this engine. The mistake I made was I measured all the pistons at their gauge point, which just so happens to be about the most structurally strongest point of the skirt. They all measured good. What I FAILED to do was measure the skirt tips. They looked fine and there was nothing that drew attention or concern, but still I should have caught that. My mistake. At least my mistakes are few and far between, but I am not perfect.
The idea that someone put out there that I was trying to hide the skirt damage by Scotchbriting them is about the most ridiculous thing I have ever heard. Scotchbrite will not fix a bad skirt. If I was trying to scam Joe or hide something I would have just bought a new piston and no one would have ever known any different. I'm not a scammer, and I stand behind my work.
Fact of the matter is anytime I am putting used pistons back into any engine, I am not going to put them back in dirty and carboned up. So I clean them in the solvent tank with a Scotchbrite pad to get the carbon off. So now this is criminal? I then use a fine bristled SS brush to clean the friction reduction grooves on pistons like these. Once they are de-carboned, I give them 3-4 strokes each direction in an "X" pattern on the skirts with the Scotchbrite pad to help hold oil on them. Been doing it for over 20 years. To think I was trying to hide something is just stupid non-sense.

Also, some speculate that the skirt got damaged when the rod bearing went bad and the piston hit the head. Two things wrong with that.

1. The rod bearing would have had to have spun the lower shell up into the upper part of the rod. That did not happen. It never spun a bearing. It burned the bearing up, and it started to stick to the crank and it blackened the rod as the bearing got damaged. The crank wasn't even chewed up and it's a stock cast crank. It just had black streaks on it, so I replaced the crank with another one, along with a new rod. The piston never hit the head. Also, that would have left a mark on the head if it did, but it did not. Plus the bearing shell would have had to have worn down to less than .020" thick and if that happened, it would have spun. As soon as we heard it start knocking, we shut it down.

2. When you hurt a rod bearing, you do not send pieces into the intake manifold. What hurt this piston was something non-metallic going down the intake and into #5 cylinder. From there it got pinched between the piston and the corner of the combustion chamber hard enough to put a dent about .020" deep in the forged piston. It then banged the piston and head two more times only much lighter as the first hit probably broke it up some. That initial hit is what cocked the piston in the bore and pushed that skirt in. I think any knowledgeable engine person would agree with that. Then, considering the piston goes up and down the cylinder dozens of times per second at even very low speeds, it doesn't take but a second or two for it to pound the skirt even further inward. I say non-metallic because there is no other damage done to the bore, or no dings in the chamber or valves. If it was metallic, all those things would be dinged up. Anyone who does this stuff for a living can attest to that.

Some say it's awful coincidental that it was #5 piston that was damaged and that's the same bearing that went out. Not really, that's only a 1 in 8 chance. That's really pretty good odds. You want coincidental, I'll give you coincidental.
My dad grew up in Iowa, but in his older age, moved to Utah. Meets a women in Utah and they get married. About 6 months later they are talking about stuff and turns out they both grew up in Des Moines, Iowa. Turns out her parents bought my dads parents house from them and when she was a young girl moved into and grew up in that same house my dad grew up in and just moved out of. This was 50 some odd years before! To top it off, her birthday is the same day as my moms, only a different year! This is a 100% true story. Now that's what you call coincidental. If that could happen, something falling into #5 cylinder is easy peezy.

So now the question becomes when did this piece of whatever go down the intake.
Joe says it must have happened here at our shop because as soon as it started, it knocked. That's understandable for him to think that way, he is new to this all and doesn't know about engines. Can't blame him for that.

BUT, lets look at this from another perspective.

That piece could have fell into the intake here, but keep in mind, between Jeff and myself, we have over 60 years experience doing this. We know exactly what happens to an engine when something goes down the intake besides fuel and air. We take precautions to make sure this does not happen. Could we still have accidentally dropped something in there without knowing? Sure. Sh*t happens.
But it is just as easy and entirely possible that something fell in when Joe and friends or the shop that got it running were putting this all together. Something could have been stuck to the bottom of the carburetor and fell in, or any other way, something could have accidentally fell in. Then the first time they crank it over to start it, it goes into #5 cylinder and hurts the piston, and as soon as the engine starts, it knocks. But you see, no one wants to think it could have been them that did this, so the blame goes to the engine builder, in this case, me. Fact of the matter is we will never know when it happened, so in this case, Joe can be the victim, and I will be the bad guy and take the blame and pay for it even though I could just as easily be the victim here.

You people in the lynch mob need to consider this before you go throwing a rope around my neck and stringing me up from the nearest Oak tree. Remember, many innocent men were strung up by lynch mobs in the 1870's without any evidence of those persons guilt, only suspicions.