serious head issues, need input please

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zinser72

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im not going to use the name of the shop as i am still giving them a chance to make things right. heres what happened: fresh motor, bought new rhs la-x heads and i broke in the cam with no problems. added inner springs (comp 978 ) and was checking the timing curve when a valve stuck.

engine had about 45 min run time on it. pulled cover and everything was dripping in oil as it should be. bent a pushrod and exhaust #7 valve stuck half open, smacked piston pretty good. 20* timing the whole time.

called the guy and he admitted to putting 8mm valves in 5/16 guides. so i sent the heads back and he "fixed" them. put them back on and after letting the engine warm up for about 15 the #7 intake stuck and caused all the same carnage.

questions:
1. any way this is my fault?
2. coincidence that its the same cylinder? it was running 180* temp
3. should i still trust the piston (kb167) thats been hit by both valves now?
4. why me?

seriously any input is appreciated. i have no money left to fix this but is it my problem or the builder's? please help me before i give up and sell the thing. ive spent much more time wrenching than driving and its getting old
 
3.Being a hyper piston, I'd toss it. If you had forged pistons I'd say go clean it up and use.
4. **** happens. I had my x heads rebuilt than couldn't use them and ended up with aluminum eddy heads. Live, learn, get luvs
 
You are using the term "valve stuck"

It may not be that a valve stuck, it might be that there is no valve clearance between cam and pistons. You have to figure out which.
 
zinser72 said:
im not going to use the name of the shop as i am still giving them a chance to make things right. heres what happened: fresh motor, bought new rhs la-x heads and i broke in the cam with no problems. added inner springs (comp 978 ) and was checking the timing curve when a valve stuck.

engine had about 45 min run time on it. pulled cover and everything was dripping in oil as it should be. bent a pushrod and exhaust #7 valve stuck half open, smacked piston pretty good. 20* timing the whole time.

called the guy and he admitted to putting 8mm valves in 5/16 guides. so i sent the heads back and he "fixed" them. put them back on and after letting the engine warm up for about 15 the #7 intake stuck and caused all the same carnage.

questions:
1. any way this is my fault?
2. coincidence that its the same cylinder? it was running 180* temp
3. should i still trust the piston (kb167) thats been hit by both valves now?
4. why me?

seriously any input is appreciated. i have no money left to fix this but is it my problem or the builder's? please help me before i give up and sell the thing. ive spent much more time wrenching than driving and its getting old
Click to expand...

It depends on what the valve guide clearance was. 20° timing is WAY too little during break in. You'll have very high ex. temps!!
Did you run the engine for 20 min. at 2500rpm?
 
5/16 = .3125" 8mm = .3149"
.3149-.3215 = .0024". That would be a loose valve to guide clearance especially if it's bronze (and I would have been pissed if I found that was the case).
I would be looking at the piston to valve clearance. As far as fault - whoever built the long blocvk should have checked piston to valve.
 
67Dart273 said:
You are using the term "valve stuck"

It may not be that a valve stuck, it might be that there is no valve clearance between cam and pistons. You have to figure out which.
Click to expand...

didnt think about that, i will check when i take it apart this time around. but when i took it apart before there was only one piston with a mark and that was the one with the valve stuck open
 
ou812 said:
It depends on what the valve guide clearance was. 20° timing is WAY too little during break in. You'll have very high ex. temps!!
Did you run the engine for 20 min. at 2500rpm?
Click to expand...

i ran it for a half hr varying rpm from 2300-2700. it was at about 28* at that rpm. 20* was initial. sorry for not being clear, temp never went over 190
 
moper said:
5/16 = .3125" 8mm = .3149"
.3149-.3215 = .0024". That would be a loose valve to guide clearance especially if it's bronze (and I would have been pissed if I found that was the case).
I would be looking at the piston to valve clearance. As far as fault - whoever built the long blocvk should have checked piston to valve.
Click to expand...

wouldnt that be the other way around? .0024 interference? im surprised they fit without him knowing it was wrong
 
Hell, I didn't even do the math.

[SIZE=-1]5/16[/SIZE][SIZE=-1] 0.3125[/SIZE] [SIZE=-1] 7.9375
[/SIZE]
 
zinser72 said:
wouldnt that be the other way around? .0024 interference? im surprised they fit without him knowing it was wrong
Click to expand...

I would guess the 8mm valves are undersize by the clearance amount, IE you SHOULD have had 5/16 GUIDES and the "5/16" valves are actually undersize from 5/16 by the clearance. So they probably are a few thou under 8mm, but still......................
 
Did the valve actually get changed out? Was the old one bent, but not resting against the seat on the edge of the bent valve?

When the valve was pulled, if it was, did it fall out or did it have to be forced out?

Pics are a good thing.
 
It may be a combination of a few things adding up to a vlave to piston that's close on #7. Like a non-square deck surface, or a hair taller crank throw or piston/rod assembly. But - something's amiss there...
 
One thing no one has mentioned. Bronze valve guides have pluses and minuses. One BIG minus to me (and it's why I don't use them) is that they CANNOT run dry even for one second. If they do, you get the result you had. They MUST be lubrcated properly upon assembly. If they are not, kiss them goodbye. I much prefer a good old iron or steel guide over bronze. They can take more abuse and they generally last longer. Of course, they are more expensive to replace.
 
Dragonbat13 said:
Did the valve actually get changed out? Was the old one bent, but not resting against the seat on the edge of the bent valve?

When the valve was pulled, if it was, did it fall out or did it have to be forced out?

Pics are a good thing.
Click to expand...

i did not take them apart but im assuming it had to be forced out. it was stuck half open not touching the seat anywhere. and yes it was replaced. sorry i dont have pics right now
 
RustyRatRod said:
One thing no one has mentioned. Bronze valve guides have pluses and minuses. One BIG minus to me (and it's why I don't use them) is that they CANNOT run dry even for one second. If they do, you get the result you had. They MUST be lubrcated properly upon assembly. If they are not, kiss them goodbye. I much prefer a good old iron or steel guide over bronze. They can take more abuse and they generally last longer. Of course, they are more expensive to replace.
Click to expand...

i could see a little assembly lube on them, it was white moly grease im guessing. maybe it only ran until that wiped off
 
and i will bust out the clay and see what i come up with for piston to valve clearance. i dont know at this point. running xe285hl cam and kb167's zero decked with .039 head gasket. how much do i need?
 
I'm pretty sure the generic number for P/V clearance is 0.080" intake, 0.100" exhaust for standard weight running gear. You can run it closer, but ya gotta have enough spring to hold them in.
 
Take the springs out on two valves, put light springs in from the hardware store that you can push down by hand, shim two spare lifters and measure the map from 15btdc on exhaust and 15atdc on intake at every degree of the crank with a dial indicator on the rocker, between those marks.

[ame="http://www.youtube.com/watch?v=ifoGVT4G0m0"]StreetLegalTV.com - Dart University: Piston-to-Valve Clearance - YouTube[/ame]
 
thanks for the help guys. i wont be able to work on it until this weekend but at least i have a game plan now. ill figure out what my clearance is and post up my results
 
IF the valve struck the piston you could have rod bearing damage there, I wouldn't run it till I checked the bearings
 
dustoff440 said:
IF the valve struck the piston you could have rod bearing damage there, I wouldn't run it till I checked the bearings
Click to expand...


x2. The best thing to do is pull that pair of rods to carefully inspect and the mains on either side of them just to make sure. You may find things ok. If it was a serious hit the piston would have shattered and really gotten ugly. But you should make sure.
 
I,d be dropping off the engine..complete to the builder,so they can diagnos what went wrong and why? and fix at their cost..with an apoligy of course.After spending thousands of your hard earned cash to them,there should be some type of warranty on an engine with zero miles.JMO Good luck.
 
i assembled the engine myself. i had all the machine work done and bought complete heads. i checked absolutely everything...except piston to valve clearance. i realize this was a big mistake. i will check it when i get the heads back again. i have pics of the head and piston but i dont know how to post them...i tried and this is the second time i had to type out this post
 
moper said:
x2. The best thing to do is pull that pair of rods to carefully inspect and the mains on either side of them just to make sure. You may find things ok. If it was a serious hit the piston would have shattered and really gotten ugly. But you should make sure.
Click to expand...

i dont think it hit that hard. the piston has marks that i can only feel a little ridge, i think i figured out the pics, these should be of the piston and head the first and second time. first time exhaust stuck open, then intake. see what you guys think
 

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