Going back to your original post I read this as you purchased the engine from someone else we will call A and had it installed by a shop called B rather than Shop B actually doing the engine rebuild. (?)
Yes, this is correct. Shop A did the engine, Shop B installed it (and did some other work to the car as well - suspension, electrical, exhaust, etc). Shop B gave me the car and informed me that the car should be taken back to shop A because there was a problem with the engine. Car was then returned to shop A, and is still there.
If the oil pressure was restored to normal by changing the over-pressure relief spring, then the original spring was incorrect or improperly installed…
“He let engine cool down, pulled release spring out, and put in a stronger spring w/ correct seal. Started car back up, oil pressure was at 100 psi. As it warmed up, the oil pressure started to drop down to 80, then 60, then 40 when engine was idling and warmed up.”
Not many shops have a selection of AMX 390 relief springs to choose from…
Lack of crankcase ventilation would have no short term deleterious effect on the engine. The location of the PCV valve is of no consequence in the short time that the engine ran. And unless the exhaust was black and the engine was surging to the point of stalling when idling a rich mixture wouldn’t cause cylinder galling in a few minutes of operating a newly rebuilt engine… Not IMNSHO, anyway.
I think there’s a problem with the engine and the wrangling over it may get tense. Shop A will blame B for an install problem and dinking around with the relief spring. Shop B will blame A for an inherent engine fault that was present from the get-go.
My gut feeling is that A is the one at fault. A dry and wet compression test will at least reveal serious issues in the top end and if one has to go into the cylinder bores that’s going to lead to the bottom end which more than likely has an issue or two also.
I also don’t see the PCV location as being a factor with these problems.
Very tragic situation considering the car. The Javelin has always been a seriously underrated and very cool muscle car. A friend used to own one back in the day with a 390/4 speed and in that fluorescent green color whose color code name I do not remember.
Right up there with the Buick Rivieras when it comes to lack of respect… 
Big Bad Green… sweet color
I agree with you ok4450 - what you are describing is exactly what is going on w/ both shops. Shop A has spent a lot of time on it though since I’ve brought the car to him, and I’m hopeful that he will follow-through and stand by his work.
Hopefully they will get it ironed out for you and I have to think the problem was due to the engine assembly process.
Fantastic car and once on the road hope you can post a pic or two.
About a dozen years ago I was seriously considering purchasing a '74 Javelin but someone beat me to it. The bodystyle is not as neat as the 69s but the right paint and wheels will do them up right.
The one I still kick myself over is from about 40 years ago when I passed on a red '63 Corvette split-window coupe for 1100 dollars.
The only thing it needed was a battery and wax…
yeah, my grandfather was gonna buy me an old javelin about 30 yrs ago and I passed. darn
IMHO there’s definitely bottom end damage, assuming you include cylinder damage in the “bottom end”. Keith suggested earlier that perhaps the rebuilder did not gap the rings. Frankly, I would not be at all surprised if that were true. For that error, I’d expect exactly the OP’s damage to occur as the rings force themselves against the cylinder walls.
Here’s one other way this could have happened - the PCV system without oil separation put lots of oil into the two nearest cylinders, fouling the plugs and resulting in raw gas washing down the walls and getting in the oil. The blowby oil also caused the smoke screen while driving. It could have nothing to do with a faulty rebuild, except for the incorrect setup of the PCV system.
If the carb was flooding that bad, the engine would not run. It certainly would not idle. it would be impossible to start…
Nonsense. Carbs work off multiple circuits. I have seen many improper set ups that idled fine and had reasonable low rpm operation but were not set up correctly once the “secondaries” kicked in. That carb needs to be set up to work with that motor- the combination of cam, manifold, displacement etc. to set the vacuum point for operation of the secondary circuits.
I posted before the information regarding the oil pressure was given so that might help explain the scoring but all the evidence of a mismatched carb are there- raw gas on piston tops and in the oil, black oil after 50 miles etc. A fried header pipe, that certainly didn’t happen during run in or it would have been noticed at some point during or afterward. Gas burning downstream of the cylinder…
maybe if the OP weighs in on who, what, how on the carb set up I will change my opinion, but not likely given the evidence…
I may have missed it, but I’m assuming that the picture titled “Vertical scoring on piston” is cylinder wall scoring on #8, right? Also, the “Fuel on top of piston” pic to me does not show a normal cross-hatch pattern (if I’m seeing it right). I’m seeing half the cross-hatch but maybe it’s the light/angle hiding it. I’m getting a feeling there are several problems going on (PCV, carb, oil pump, rings, cylinder finishing, ???).
Twinturbo - but if the carb were flooding that badly, why would only two of the cylinders be affected?
Another thing to add was the car was running fine. I think #8 was weak, and it may have been operating more like a v6 than a v8, but beyond that it had plenty of power. If it weren’t for the smoke I (though I’m not an expert), would have never guessed anything was wrong.
The engine only seemed to be running fine. The condition of the sparkplugs is evidence to the contrary. The oil buildup on the plugs plus the scoring of the cylinders tells the tale; at least two of the cylinders are damaged and oil is passing the rings into the chamber.
Rich operation causes carbon buildup on plugs, but not the kind of deposition your plugs exhibit, and not generally on only isolated cylinders. And I fail to see any possible way a misrouted crankcase ventilation system could cause this either.
I believe Keith was probably right. I believe the rings may not have been properly gapped. As piston rings heat up, the metal expands. That causes the rings’ arc lengths to grow. If there’s insufficient gap in the ends of the rings to allow expansion, the existing gap will close up and the diameter of the rings will be forced to expand beyond what the cylinder can accommodate. The rings will become too tight in the cylinders and force themselves into the sidewalls with too much force. That damages the cylinder surfaces and destroys the ability of the rings to properly perform their “wiping” of the cylinder walls. At that point, oil can pass the rings and load the plugs up.
That makes sense. Only puzzle to me is the fuel buildup on top of the intake valve and on the piston - that’s like 2-3 tablespoons on top of the piston.
Smokey Yunick never would’ve let this happen.
You’re feeding a lot of gas in with that carb and if the cylinder isn’t firing it can puddle. If the cylinder isn’t firing because of a gumped up plug caused by torn up cylinder walls… caused by what I described above… it’s also likely to pass by the rings during compression and dilute the oil, so you’re likely to see that too. Pooling on the intake valve may have simply been splashback from the puddle on the piston.
I think you should reconsider your carb size. But I also think you have more serious problems to solve first.
If the engine hasn’t been torn down yet, and it will have to be eventually, start by loosening the nut on top of each of the rockers 1.5 turns. Then turn each another 1/2 turn and see if the rocker is loose. If it is not, then the rockers/lifters were not adjusted properly. The only ones that should not be loose are ones where the valves are open, that should be half of them. Turn the engine 360° and the ones that were tight should all be loose.
I once had a neighbor who did this to his brand new chevy engine and had pretty much the same results as you did.