Yeah when you take it to the machine shop they should be able to tell what caused it to eat the valves like that , See what the other side looks like ,but if its just that side i would think carb or intake or just a head problem .... Lew

 

I am surprised no one has seen that before??? I would say, that was the reason the truck was parked in the first place.

Many reasons for that condition. Most common, is severe over heating, in the back half of the engine. Keep in mind, and double check the fireing order, it is also common those back cylinders are fed last, and tend to run lean. Especially a problem on high HP engines running nitrous. That condition didnt come from sitting. I would be concerned, moisture may have gotten into the cylinder though. How did the walls look in the cylinder? Try to flush you water passages out to, Sometimes windsor blocks will plug up with sludge in the back, and you will notice the exhaust manifold turning red hot, from exactly that. ( you picture)

PS I realize yours is not a windsor, but used that term as an anology. ( I better disclaim my statements for fear of people that all of a sudden know more, running with it ) LOL

 

I would check out you carb, maybe only one of the two barrels is working properly causing a lean condition in one bank.
-Johnboy

 

Thanks for the comments. Mustang, it wasn't the rear cylinders it was all 4 cylinders on the driver's side head. The cylinder walls look good. I will flush the block. This thing is bone stock F250, no nitrous. I agree, I don't think these valves got that way sitting in the driveway.
Johnboy, I was thinking lean on one barrel too.
I took the heads to the machine shop today. They are going to let me know if they are buildable in a couple of days.

 

I was honestly impressed with how good the seat looked. LOL. My bet is a simple rebuild if you will.

 

After you send the heads out i would have a good look at the intake & carb , if all the valves burn't on that side because of a lean condition makes me think bad carb or big intake leak on that head . How did the intake gasket look when you took it off . If your not going to rebuild the motor i would clean the valley of the motor real good & look for cracks especially around the water jackets , thats a good place for a crack , if the motor ever overheated bad , sometimes there hard to see . I would rebuild or replace the carb if you think its suspect....Lew

 

Before he can go out and start trouble shooting, he has to see what the cause of the valve problem...

Fact is, in the 70s more so in the late 70's all Company's where using lousey metal. Look at Chevy and there soft cam issue's. One could think they had an oiling problem, when they see the lobes wiped off...

If the oil looks fine, (not like a choclate milk shake). And the Anti freeze looks fine. ( No oil) and the Spark plugs look fine, ( Nice tanish color) I would leave all alone, get the heads redone, and roll with it. If there is going to be a problem, it wont run right. Then you trouble shoot. In all actuality, it was darn lucky you happened to take the head off, because next thing that would have happened is the valve head would have broken off, and then really caused some grief.

I am not a big fan of throwing cash out the window, and creating problems, or chasing ghosts.

I am curiouse to see what the machinist thinks caused this...

 

Wow dude im just saying when he has the time to check some things out . It dosn't burn 4 valves on the same side for no reason . Whats wrong with trying to find out what the problem was ??? I just said if it turns out to be the carb rebuild it or repace it . And if he isn't going to rebuild the motor checking it over good my help..And i know what a burned valve looks like thats why in my post i mention carb & intake, two likely causes . Your idea overheating & thats possable to ..So your saying i shouldn't try to help...Lew

 

Why did you edit your post mustang ????

 

These heads have been rebuilt before, by looking at the hardened seats on the exhaust. Check to see if the head gasket was instaled properly. The side marked "front" in the picture was it installed towards the front?

 

Seems the PO lied through his teeth....

 

I have to agree, It made me wonder , I thought it was only the rear cylinder... but all 4 in the same head...

 

the carb/manifold doesn't supply fuel to one bank or the other unless it's an SP2P manifold or an Offy 180*? and how do the rear cylinders get 'fed last", i thought they all draw from the same plenum? i've heard the myth of the rear cylinders running hotter a million times, might wanna think about where the vacuum taps(and leaks) are...



i'd also try to figure out if the head gasket was on backwards, and check the plugs to see if they're the same side to side

 

I found that out last night with the air hose. One barrel feeds 2 cylinders on each bank, not all 4 on one bank. There goes another theory . . .
Another oddity. For some reason the valley pan gasket has holes rusted through it. Never seen that before. Don't know if it relates, just thought it was weird.

 

yeah, i've found rust pinholes in the valleypan before, that's why i prefer to not use them any more, or at least put something on them to protect from rust.