rockjeep73

Well last time we had the truck out to the track we decided to lean on her a little and break into the 12's, asking too much out of a mildly built VE-pumped 1st gen with a stock 3 speed auto...maybe? So we bumped the timing up to the head, only about a 1/16" farther than it was, and took it for a spin, truck sounded the same and smoke was less at full throttle, EGT's were climbing slower, and power felt about the same(hard to tell), just what we were looking for. Then we mixed up a gallon of 75%methanol/25%water and poured it in, I usually run 50/50. Adjusted the hobbs switch to bring the w/m on at 25psi, prior to this it had been set at about 35psi. So we get to the track and 1st pass I run it out to about the 1/8 and get out of it because something didnt feel right, come back check it and everything seems OK. So I go back for another pass and lay into it all the way down the track and the thing must have been eaten itself up the whole time because it only ran a mid 14 or something. So I drive pack to the pits and it is idleing like crap, just like it did when I had popped the headgasket, and there was coolant coming out from the HG, so at this point I was thinking that it was just the HG. Well now I wish it was because this is what I found.

#1 piston is toast, 3 others have some visual damage.
So what killed it, w/m, timing?

JD730

That stinks. I guess when you play sometimes your gonna have to pay. It looks like it scuffed/scored #1 up pretty good. Looking that the last picture it looks like the injector isn't spraying in the bowl very much. From what I understand #1 cylinder is air challanged so it was probably just a little hotter than the rest of them. Probably enough to damage it more that the other pistons you noted.

I didn't realize the combustion bowl design was so different from the intercooled trucks.

Begle1

Wow... Don't know what that looks like...

Other than I had no idea that we had such funny shaped combustion chambers...And isn't that a sleeve around there as well? Looks like one...

And just for another periphery question, how hard is it to rebuild one?

12vchevydually

We have done that a couple of times on our truck that we haul cars with, the fist time it happened was 500 mile from home, 48ft trailer and one car on it. My friend had to drive it all the way home hammering. The second time it happened was 200 miles from home and the truck and trailer weighted around 28,000lbs. Had too drive it home like that again hammering. We found out that we had a injector Popping off early. I would have your injectors pop tested and see what they are going off at. I really think that you will find the block is ok and that it is just coated with that aluminum from the piston.

lovemysan

How many miles were on that? I can still see the cross hatch. I must admit I felt an immediate let down reading this thread. I'm saving for a locker. Going for low 15s with stock injectors.

Begle1

I've heard that cross-hatchings remain visible at up to 300,000 miles, so I don't think that's too good of an indication.

So an early pop-off, eh?

JD730

On mine cross-hatching was very visible at 230,000.

12vchevydually

Maybe, I am no expert, I am just throwing out some idea's from exp. I have had in the past. These block bores are totally unreal. I don't think the metal they used is not from earth,LOL. Everytime I pull a head off one I am like . Even with all the hard miles we put on these, right on the edge of things melting or melting . The pistons we pulled out of ours looked worse then those, well one of them did, OUCH!!!!!!!!!!!!!!!! We just cleaned the block up with a hone and slapped some new pistons in it, we didn't have the time for the down time too take it out and have the block gone through.

12vchevydually

RockJeep what kind of EGT's where you seeing?

Underpsi

Wow sorry man that is depressing, hope you get her all fixed up. Maybe a set of marine or performance cut pistons?

rockjeep73

EGT's were never never an issue as it started burnin up before it ever got that hot, and they only get as high as about 1600-1700 at the end of the track.

Im thinking that the last little bump in timing caused it to spray out of the bowls and that with a set of injectors that probably arent balanced too well out of the box. Number one could have been popping early for all I know.

12vchevydually,
Where did you get your new pistons from and what do they run for price?
The block looks just fine, just some aluminum from the piston built up on the wall. The motor only has about 130,000mi on it so im trying to decide wether or not to rebuild the whole bottom end or just slap a new set of pistons in it.

Also, what are the differences between the marine pistons and the OEM, I have heard that the marine ones are stronger but heavier?

Thanks

signature600

Might as well do it right...the only real extra cost would be any machine work for the crank/rods!

JMHO,
Chris

bgilbert

You can see those 4 hole POD's weren't spraying good into the bowl. A thinner washer would help. But yes I know, not with the nonIC'd head. I wouldn't use marine pistons. They won't match those edm's you plan on getting in the future. Then again, they might match the POD's since they are a marine injector. We don't have too many choices on pistons. Cummins or Scheid ' Arias' pistons I believe.

I'd take your time, do it right. 14mm head studs, maybe a hot cam, new 7mm head, new pistons etc etc etc..

haloman

I think I can see why I haven't turned my truck more than it is. Just seeing that carnage makes me wince.

G1625S

I 'might' go pull some timing out of my truck in the morning...but I think the extra meth is what broke that camels' back. Sorry to hear of your misfortune, Rock. I guess you're stuck driving that boring old 13 sec. truck now, eh?