car blew up lastnight...

[3vs197]

so long story short my full bolt on, nsr cammed GT had an engine mishap. Racing a buddy in mexico and it just started to mis fire really bad but didn't really make any noise. got it back to the shop and pulled the heads off the car and found one broken exhaust valve. the valve stayed in the head so luckily it didn't hurt the bottom end.

just finished putting comp valve springs/retainers in the car and it ran fine for several days before this. i did bump the limiter in the race but didn't think anything of it (7200). it broke the guide off the head where the valve seal goes over.

im really shocked that this happened and my buddy said it is most likely a defect in the valve and see no reason why it broke. like i said it was a clean break and the stem itself looks good. the follower stayed in place and the follower/cam appear to be undamaged.

several well known shops told me to shift@ 7k and set the limiter @ 7200. So im really confused as to why this happened.

i plan on getting some used heads with stainless valves and a valve job and putting it all back together with 2v iron tensioners instead of the plastic ones.

thoughts? comments?

 

[fdjizm]

Wow that sucks bro, I agree you should be able to shift at 7k all day with that setup.
Just the luck of the draw I guess.

 

[Daniel Day]

Dang dude, sorry to hear that but like you said, at least the bottom end wasn't damaged. Hope you get it up and running quickly.

 

[3vs197]

i really hope it was a fluke but if something caused it i would really like to know why so i can fix it and stop it from happening again.

 

[RedMustang]

what's your plan ?

 

[3vs197]

well at minimum i would like to get stainless valves with a valve job and put it back together. but if i can find enough coin i would like to get some flat tops with used 04 cobra rods and get that machined/balanced with a stock crank.

 

[JeremyH]

Valve seal maybe? I put in new seals when the comp springs and retainers went in.

 

[3vs197]

the seal looks fine. but the part of the head where the valve seal slides over broke clean off the head. my buddy said sometimes due to friction the valve can get stuck in the head when it gets hot but it came out without too much trouble and it looks clean still and he said it wouldn't look so good if that were the case. i just don't know if this is a fluke or not.

 

[GrnBullitt08]

Didn't you just install Comp Springs? Maybe an install mishap?

 

[3vs197]

yes, springs and retainers but my issue with that is a problem there would have been evident immediately. i drove and beat on the car for 3 days @ 7 to 7200 rpms and it ran like a top. i used the stock keepers so i don't know if thats an issue?

 

[GrnBullitt08]

Gotcha... Well sorry to hear about the motor mishap man. Shit happens.



And to answer your question on the keepers you should of been ok. But with that 7000+ rpm range anything can happen. That's alot of stress on the valvetrain. Did you tear anything down yet?

 

[3vs197]

just the pass side head/front cover, etc...ill get the driver head off this upcoming week. no rush though as i have to find a head/heads first.

 

[GrnBullitt08]

Look in the classifieds ive seen a few sets of stock heads in there.

 

[3vs197]

yea i pm'd ibadhrse about his but would like to just find one head if i could. i really hope this was a fluke cause if i put it back together and it happens again, ill be f'ed.

 

[GrnBullitt08]

Are you looking for an assembled set of heads or bare?

 

[3vs197]

bare is fine cause i will be buying valves and already have cams/springs. you got something in mind?

 

[slow06stang]

I have a good passenger side head pm me if interested.

 

[Vxer1000]

Where exactly is the break in the valve itself? Is it by the keepers or somewhere in the middle of the stem? Is there any scoring on the valvestem itself? That really sucks.

 

[NastyStang113]

Who did the install? Maybe they messed it up.

 

[3vs197]

i did the install and its pretty hard to mess it up. it gets put back together right or it doesn't work at all.

and the valve pretty much broke right in the middle. and it looks like a really clean break. no scoring on the valve. and when you hold the two pieces together, its not even bent.