spunky602

hey all.. these are L92 heads on a 408.. the car had been smoking white at idle for a whileand makingreally good power... a few days ago i sprayed 100hp
after that the smoke stopped... but a day later i could feel something went wrong because the car doesnt sound the same and lost alot of power

so i pulled out the heads
could a stuck open injector cause this?

Randy WS6

iTrader: (69)

Looks to me that you might have a broke ring, Did you run a compression test first before you pulled the heads.

Sales2@Texas-speed

iTrader: (5)

What does the piston look like?

LS6427

iTrader: (2)

Have you checked the valve seal in that hole? Here's what mine looked like when EVERY one of my valve seals went bad and drove it for about 3 months till I pulled the heads off to have them rebuilt.

I know these are pictures of the pistons, but my heads and valves also looked like yours. Don't see how a stuck open injector can do that, that would just cause it to be rich as hell and cooling it. No???

Bump the key to move the piston down in that hole and check the cylinder wall for any scoring/marks?

.

spunky602

compression was actually better than others.. in the affected cyl it was 9 and 8.5 in the first in the same head
the piston seems to be fine and so does the wall
but i found something broken in the head
what i don't get is what went wrong.. i used to pull that plug once a week to clean it because i didnt feel like pulling the engine apart,, why now suddenly it stopped workin?
i know i might sound dumb but i dont have much experience here

Randy WS6

iTrader: (69)

On the pic that you have on the piston in the bore, It looks like the valve has hit the piston on the top intake eye brow. You may have a bent valve or bad guide
and on the top pic of the head the intake valve has a mark on the top near the spark plug hole .The valve looks crusty from the build up but at the top of the valve , it looks smooth were it has touch

Randy WS6

iTrader: (69)

Also check the rocker arm, from the looks of things, When the valve hit the piston it drove the valve stem up into the rocker and flexed it enough to brake the pedestal, You are real lucky that you did not drop a valve. What size valves are they ? From what i can see the piston beside it has also has the mark on the eye brow , but cant really tell with the pic.

spunky602

yeah .. a mechanic inspected the car last night and told me that my valve has kissed the piston.. but that doesnt really explain the carbon build up that has been going on for quite some time.. cleaning it was a pain in the *** specially the black oiley sludge in the exhaust runner


so back to my original question ... an injector stuck open for 3 months could have caused this?? or was the valve guide leaking oil into the chamber??
i used to refill oil every few days .. it consumes around a litre a week if i race alot...

Beaflag VonRathburg

iTrader: (176)

That is oil in the chamber. Fuel doesn't smoke white, think about diesel trucks. I would look at your PCV setup and work from there. The way your headers look whitish looks kind of like coolant got spilt on them, but I could be wrong.

cam

iTrader: (9)

Looks to me that there was clearly contact with piston to valve. Probably bent the valve a little which has taken out the valve guide and broken the saddle from incorrect geometry. If the valves bent in the middle and the guide is trashed then it will allow tons of oil into the cyl which is sure what that is. No way fuel could cause that usually overly rich conditions wash the pistons clean rather than gunked up with crud like that.

Either that or its a ring blown off ( Could be BOTH ) but there is definitely a head problem. Was the valve spring broken?

One thing to keep in mind is a heavily oiled cyl will raise the compression.

spunky602

aha... the spring was intact but it took alot of force to remove it as the valve was stuck.... what causes the valve to hit the piston? i have been told that a low compression piston should have alot of clearance

Randy WS6

iTrader: (69)

It looks to me that the valve diameter is to big for the valve pocket, when you have a piston to valve clearance problem it from the cam having to much lift or duration , over revved or valve float or a miss shift. But the problem that your having is the valve is way to big for the pocket not the cam lift. You need to mic the diameter of the valve and the valve pocket and i would clay the piston to check the clearance,You have hit the top of the piston, your valve should be going down in the valve pocket ,If the valve pocket was the right diameter for the valves that you have, you would not be having this problem. You will need the pistons fly cut for your valves. Now for some reason if the valve pocket is right , then your guilds are shot, letting the valve move horizontally in the head moving the valve out of center slapping the top of the piston.

spunky602

the heads are stock.... maybe its over revving.. last time i sprayed it missed 2nd to 3rd even though i released the nitrous button at 6700 and it was suppposed to shift at 6850 but it went to cutoff at 7200
thanks for the help guys... i'll check for bends and replace the guides and maybe lower my cutoff a bit

speedracer2536

iTrader: (15)

You should really put the car on a WOT switch.. Having to hold a button sucks *****

Randy WS6

iTrader: (69)

What your saying is most likely what caused the problem, But the L92 heads have 2.160" int.valves not the standard 2.00" in the LS1 style head, Whats is your pistons max valve dia.valve pocket ? What im trying to say is, the valve dia. is to large for the valve pocket on the piston ,That's why the valve hit the outer edge of the valve pocket. The valve should go down into the valve pocket

TransWS6Am

iTrader: (41)

off topic but i noticed you are running green coolant. I thought green coolant was a no no in aluminium blocks? iv only here ran the orange dex-cool. or is the green coolant thing a myth.

Randy WS6

iTrader: (69)

Most of all the coolant are now compatible for aluminum blocks, no mater what color they are.

briancb1

The green coolant is probably fine.

Your setup was under-springed for a 7200 Rev or even a 6800 IMO.

Hell I have LS3 valves, dual springs with 160 seat/448 open and Ti retainers and I wont get it that high up there. You pretty much solved your own question bud. Good luck with your fix.

Beaflag VonRathburg

iTrader: (176)

This is a very good point. I know Wiseco switched over to a multi valve usage valve relief a couple years ago. You'll see some companies label the pistons for certain head usage.

I think 7200 RPMs with your valve train setup might have had something to do with it as well.

madmax4499

iTrader: (3)

hard to tell in the pic. but it looks like a bent valve, if you look at the exhaust seat it looks like it was not sealing. that would not allow for good combustion and would make the chamber look dirty. let us know what you find.