MackTheFinger

It's a shame that happened and a testament to you that you loaned them out to begin with. Thanks for being a good guy for so long!!

Was there a price?

Musta snuck across the state line..

I bought a 5 bolt Dakota rearend from Falconvan for my '47 Plymouth but haven't gotten around to installing it yet. I believe the Dakota has somewhere around 3.55 gears. He relocated the spring perches and rebuilt the rearend but ended up using an Explorer rear. My car has already had the u-joint conversion completed so it should be an easy swap. The original rear is working fine, brakes are good, etc. so it's not a priority. I'll post results when I finally get around to changing it. That's my 100th post!! I'm getting way too gabby!!

Along with your son helping out that was my favorite part of your brake install. It will surely help those of us contemplating a similar upgrade. I'm sure the spacers will work out fine. I hope your trip is going well!

If it's only a matter of grinding a little of that rib in the middle picture I wouldn't hesitate to have at it. Good luck and thanks for posting all this info. It will help many people who are thinking of doing the same conversion.

Sorry to read of your problem. Persistence is the key here.

@Don Jordan < I'm almost tempted to put a 283 in it and call it a day. > If I were you and had a 283, transmission and rear end I'd probably put 'em in and be back on the road before the machine shop was finished with the other engine. It would be nice to keep the car all original but what the heck

I have a picture of me on my old knuck but don't want it public.. I'm still undercover..

Thanks for the pictures. The hole in the Guzzi rods look about like that. I would think a lower end loose enough to bend a rod woulda been hammering hard enough to hear it and cause the oil pressure to be nearly non-existent. Broken ring causing the damage, maybe.. My brain wasn't fully warmed up this morning or I'd have remembered that small block Chevy motors have a notch in the rod to squirt oil at the cam and some of it must be intended for the lower cylinder walls. I've been focused primarily on motorcycles since the late '70's and it's been a while since I paid much attention to automobile engines.

I'm fairly comfortable with my lean cylinder idea but came up with a couple of other things to think about. Many years ago I noticed that the connecting rods in some Moto Guzzi motorcycle engines have small holes drilled in the upper bearing area to direct oil spray to the cylinder for cooling. I asked the only Moto Guzzi experts I knew at the time and they said that what I saw was normal, some engines were shipped that way and some weren't. I believe they finally decided that it wasn't necessary. Someone with better knowledge of the oiling system in the Mopar side-valve L6 could tell us if there's a possibility that an oil distribution problem could lead to a lack of piston lubrication in only one cylinder causing it to overheat. At the other end of my lean idea is the possibility that dpollo brought up, an overly rich mix washed the oil out of the cylinder and caused the piston to overheat. It's a little difficult to see how a leaky fuel pump would cause that, though. I'm not comfortable with the bent connecting rod idea because it brings up the need to explain how the rod got bent. The Harley engines I've encountered with bent rods had either been run too hard, worked on by someone with a 12 lb. hammer, or both. It seems unlikely that an engine with the reputation of the Mopar side-valve 6 under normal usage would bend a rod. Unless some other idea comes along I'm still leaning toward additional air somehow getting into the cylinder.

Thanks for that update! My lil bro lives in Minneapolis! I'd have you wave at him if you see him on the road but he drives a Volvo XC90. It's generic enough it would be hard to find in a parking lot.

That may be a possibility. I've seen a lot of bent rods in Harley engines but generally they'll spit out a wrist pin circlip while the piston twists around. Thanks for the Christmas wish but obscenity really isn't my thing..

I stand corrected. I had forgotten that. Thanks!

Enlighten me, Reg. What's your theory?

The same fuel mixture is NOT necessarily delivered to all cylinders. There's one intake port per cylinder or there could be a leak between the head and any particular cylinder, neither of which would affect the other cylinders. Since the head had been removed prior to this problem that's where I'd look first. In the absence of any other evidence an overheated, burnt piston with collapsed ring lands supports the theory of a lean fuel mixture.

I appreciate what you're saying with a few caveats. First, I started playing guitar about 1965 and still don't feel that I really know what I'm doing. I treasure constructive criticism and advice to better inform and make me a better guitarist. The same can be said for my mechanical abilities. I still learn from my own and others mistakes. Second, I've hired more than one person to work for me who had 20-25 years experience but apparently, just as with some of the mistakes I continue to make; they just did the same thing over and over and over. A third caveat is that I've worked on many vehicles that had problems the owner never noticed. I think some of these problems came on gradually and only became evident when either someone else drove the vehicle and noticed the problem or there was a catastrophic event like a collapsed, burnt piston.

I didn't mean to give the impression I was trying to bust your chops and I apologize if it seemed that way. You give a lot of good advice and seem to have less ego than some. I was taught to envision fuel mix issues by thinking about an oxyacetylene torch. Spark it up with just the gas turned on and it'll blubber and smoke until you give it some oxygen. The more oxygen you give it the hotter it gets, right up to where it'll melt steel. In my opinion that's what happened in the Zen Master's engine. Somehow there was more oxygen introduced into the cylinder, the piston got red-hot and expanded enough to decrease the clearance until the piston scuffed. I suspect there was some detonation or the ring lands wouldn't have been hammered. It's a reasonable explanation until a better one comes along.

Right on. If a carbureted engine runs perfectly at sea level it'll run poorly at 6,000 feet due to the decrease in oxygen. Most engines aren't optimally jetted so it's not always severe enough to be noticeable. Computer managed, fuel injected engines vary the mix so it's not an issue with them.

Wow right back at you.. I didn't call you an idiot and won't now but for some inexplicable reason you tore down what was by your accounts a perfectly running engine and found a burnt, scuffed piston with collapsed ring lands. Pistons burn and ring lands collapse because they've been overheated. Your machinist told you the damage was caused by overheating. Have you told him he was wrong, too? I offered my opinion in good faith but I'm always looking for enlightenment. Have you come up with another reasonable explanation for the damage other than the errant wire brush fragment theory?

It's a given. Less oxygen=richer mix.

How many symptoms do you need? You've had two people tell you that it looks like a burnt piston. The symptoms you have, burnt piston and collapsed ring lands; indicate that the cylinder ran lean. If you think the piston just decided life wasn't worth living and decided to self-destruct; go ahead and put a bunch of money and new parts in it and hope it won't happen again. In fact, I suggest you do exactly that.

Something caused that cylinder to run lean and overheat. I'd make sure I knew what caused it before I put it back together.

That's a cool piece!!

Sorry to hear you're having problems and kudos to Rekbender for offering free parts. It's impossible to be 100% certain what caused this but every time I've seen a motorcycle piston that looks like that it's been caused by a lean fuel mixture. I've attached a picture of a piston from a fairly fresh Triumph Bonneville rebuild that shows nearly the same scuffing and I know it was caused by a lean mix. Collapsed ring lands are generally caused by detonation, again a lean mix problem. When you re-assemble your engine be sure to check for an intake leak on that cylinder. Good luck!