i am really let down that GM chose to go with such a cheap valve in these heads.

the valve stem broke in my engine last week, some of you already knew that... but i am still irritated about it. luckily though, since i put a cam in the engine, warranty did not cover it. YAY! i guess i knew that going into this, but i hoped that they would cover it still, since it was a defective valve.

i was cruising home about 50 mph when it happened, sounded like a bucket of bolts in there. the stem broke right under the retainer, i have the piece in my pocket actually. the locks and retainer are still attached, just a clean break on the stem. you can see the shiny and dull spots on the stem where the break occured, and it looks like a cast valve... like some kind of shitty metal was used to make this valve with.

oh well, i found a built 377 with 0 miles on it, stage 3 patriot heads, and a fairly large custom grind cam in it... for a very reasonable price. it is going in as i type this... hopefully it will be running by this weekend, and retuned by next week.

the head didnt look too terrible, but the piston did. probably since i drove it around my yard, then on and off a tow trailer and around the dealership with a valve in the cylinder clanking around.

i expect the new motor to be well over 500 rwhp on the juice.

stay tuned.

 

Shoulda kept driving it

 

Is there any evidence of valves hitting the piston on the other cylinders? Usually when a valve breaks like that it's because the piston hit it. I know the 4.8L has flat top pistons, and the short stroke degrades piston to valve clearance. Were you running LS6 springs?

 

If you were worried about the warranty why didnt you pull all the performance parts off?
The time spent pulling off parts probly would of saved you a few thousand dollars.
Even if it costed you a days pay for missing work.

 

i havent pulled the other head yet, but all the pistons looked perfect on the other cylinders.

all of the plugs looked great too, even the one in number 3 cylinder where the valve broke.

and YES, i was running ls6 springs.

 

well, mainly because i tossed the factory pushrods and springs, and didnt have that option. and secondly, i thought my buddy at the dealership could "pull one out" for me.

no biggie, i would have rather saved this money though.

 

ohh the buddy hookup yep thats a 50/50 shot most of the time
those parts are a dime a dozen
kool,hey if you got it may as well spend it you cant take it with ya

 

this is true. i just didnt want to spend it, my sons first birthday party was 2 days after my motor let go. i had to downsize the party a little to buy a new motor..

hell, he probably wont remember his 1st birthday anyway right?

 

was ls6 spring the cause of the failure?

 

the shitty valve was the cause, as far as i know. the spring never let go, nor did the retainer or lock.

the valve just broke..