What is the highest mileage nailhead you have or know of? Are there 200,000+ mile ones out there or don’t they last that long without a rebuild? One of mine is at 111,000.
My Father had a 66 Wildcat 140k sold it for a few hundred guy drove for years T400 shifted like new lol
Bought mine 66GS back in the day at 85,000 and it still ran great at 120,000 +. Like 71stage the St300 ran perfect too. I still got on it with higher miles also. I only replaced the nylon timing gears with a steel set because I had the opportunity as I broke the bolt on the timing chain cover while putting a new water pump in. The nylon gears were still fine as this was around 1982 and they didn't seam? brittle yet.
I think it is the aged brittle timing gear that causes these motors to fail more than mileage. Cheryl
The 66 GS I parted a couple years ago ran excellent with no noise or smoke and had 190k on it. Upon disassembling I found a ridge at the top of the bores that would probably require more than .030 overbore to clean up. The lifters were cupped yet no valve train noise. At sone point the nylon upper timing gear had been replaced but thats it.
I honestly thought my GS had 93k on it because of how well it ran. After pulling the heads there was no question it was double that.
Just my own opinion based on the 3-4 engines I've taken apart.. over 100k, the OEM pistons will crack. Some will have no outward indications and run like that for another 100k miles, some will make noise, some will come apart but not hurt a thing in the process, some will destroy a perfectly good block. It doesn't seem to be contingent on severe duty or not, it's just a crap shoot. I would love to be wrong about this, but somehow I dont think I am..
That's one of the things that convinced me to rebuild mine at 136K. I spoke to a few seasoned people who all said basically the same thing. This is what was left of the OEM nylon timing gear that I took out. The engine ran fine; at least pretty good. But it was a ticking time bomb. I wanted to redo on my terms and not have to deal with catastrophic failure. I'm hoping the rebuild will be good for another 60 years at least.
I managed to get to 108,000 miles (173,809 Km) on my girl and suddenly I couldn't get any fuel. After fumbling around for a while with a new pump and an underpowered electric fuel pump, I took it to my mechanic. He told me that the engine was in desperate need of a rebuild (one lob on the cam was completely rounded off) The fuel problem was simply a loose bolt for the fuel pump on the camshaft. He needed $9,000 to rebuild the engine. Nope, can't afford that, now. Ray was rebuilding it before he got sick. Delays..... delays (said in the voice of Marvin the Martian).
I agree with Cheryl; I don't think that the later Nails have any particular weakness other then the Nylon gears. It's interesting that the Nailhead has pretty much the same lubrication system as the early Y-block Fords, but the Ford V8 had monumental lubrication system problems, and the Nails had practically none unless the owner didn't believe in an oil change once in a while.
I took a factory piston with a very long spiral crack in it out of a slightly over 100,000 mile 264 that ran great. I was freshening it for use in another car. I had flogged that engine unmercifully, so I don't blame Buick for the piston. That was the engine that I installed into the '55 Ford.
mine made it to 143,000, smoked like a freight train. when I would stop for gas I put a couple qts oil in it too, but was still going when I decided to rebuilt it.
