Our tow rig motor finally gave out at 296k.. We were pulling the black truck to the drag strip the weekend before Houston and everything was fine, then all of a sudden the truck ran rough for 10-15 seconds and died.

Engine would crank but would not fire, sounded like it had no compression.

Rewind a bit. A few days before we left for the Shelbyville KY pull we took the 160 pump off and put the (tuned) 215 pump back on.
It was supposed to be pin-timed at 20 degrees, I found out on the trip that it was much higher (26.5 degrees) and we didn't have time to re time it.
On the way there it was blowing a LOT of oil, presumably blow-by, but some was also from the front crank seal leaking (again). Then it seemed like the timing slipped and the blow by decreased along with power coming on closer to 2000 rpm rather than 2500.

Truck has a 64/14/71 turbo with stage 3 injectors and a ported head.
Has a NV4500 RPM with 4.10 gears so most of the pulling is done at 2300-2500 RPM. Head and block are cut for fire rings.




I hope this valve job can be saved.. We'll see next week.


Notice how all the other pistons have crap in them from #6? Even number one had them!





Have to get that one straightened, does anyone have a pushrod straightener I can borrow? LOL


I am surprised how the aluminum managed to spread itself to the other pistons.. Not quite sure how that works.. Maybe someone can offer some insight..


The right valve pictured is the intake valve, notice the buildup of aluminum shavings.

 

Should buff right out, I'll just take some sandpaper to the cylinder wall and chip the extra pieces off the piston so they don't get caught in the valves.

What do you think guys, will 20 over be enough to clean up #6?

This engine had 296k miles on it. All over the other cylinder walls were perfect, all still have visible cross-hatching present.

 

A couple a gallons of this stuff and she'll be good as new.

 

Nice photos. Ouch, reminds me of a Datsun B210 which dropped its valve seats on the pistons. Hope you have a good machine shop. If I had an engine nightmare this would be one. Post some pics. after the shop work.

 

Will do, my machine shop does great work, I'll follow up!

 

As the valves start to go all that piston does is pump air (and melted aluminum) back and forth. It'll blow some into the intake and the good cylinders will suck it in. Sorry to see it's this bad.

 

MAN that had a really high suck factor.

 

Man, that sucks. Looks like a new sleeve in #6 to me.

 

Yeouch! I hate that for you. Still good life out of it, but sounds like it had a couple hundred k miles left if crosshatching was still present at 300k.

 

At THAT is what excessive timing can do!

I bet EGTs were under 1300 the whole time, eh?

 

Ouch, Melty Aluminum not good.

 

looks like the other cylinders have the crosshatching on the wall still right??
not bad for almost 300k
I too would like to know what your EGT's where??

 

Wow. Crazy pics! Time for more upgrades!

 

dude thats insane!

 

Exactly, I have had this happen (more than once )in my BBCs when a too lean situation with too much nitrous melts down one or more of the pistons, the chunks swap holes from one end to the other. If its just the aluminum from the piston your seats and valves should clean up OK but if there's any ring or Cyl material trapped in there its a different story. I once had a nitrous backfire that made a LS7 connecting rod look like your S shaped pushrod
Do you think the timing was the cause? Thats a lot for a 913 pump