Car is cursed

69gmachine · Oct 20, 2008

I was on my way home from this month's local Mustang club meeting Saturday when the engine suddenly started making a bad popping noise and lost power. I nursed it the rest of the way home and pulled the passenger side VC. The #2 exhaust valve spring was broke in 3 pieces. The valve was stuck down. Not a good sign.

I had replaced all the factory springs when I rebuilt the valvetrain last year with the bee hive springs from Comp Cams. The only thing I could find on the internet as a cause for spring breakage was corrosion (new, there was none) or fatigue (don't see that either). I'm guessing they were not properly heat treated, or it may have been a bad batch of steel. It failed at the top of the spring where the diameter reduces.

Yesterday I pulled the head and sure enough the valve is bent. Smacked the piston pretty good, but I think it'll be OK. I really don't want to tear down the engine again. I've got the head ready to ship out tomorrow. I see my plans for the Pony drive going up in smoke already

mrmustangman357 · Oct 20, 2008

sounds like comp cams need to make this up to you - bad

why does the head need to go out? did it mess up the seat? You should be able to pop a new vale in and hand-lap it then ur done.

but at a min. comp cams should "comp" you a new valve and a full set of springs, locks, retainers. . .

POST PICS TOO if ya got em

10secgoal · Oct 20, 2008

How close to coil bind ?
Pics of the piston....probably just fine man. Don't fret yet man.

woodsnake · Oct 20, 2008

Ah, performance cam? Did you measure for correct pushrod length?

ForceFed70 · Oct 20, 2008

I havn't been hearing a lot of good things about beehive spring lately.

Having said that, I'm wondering the same thing as woodsnake. Have you checked pushrod length? If it's a 69/70 block, you need shorter pushrods than what all of the other 351W's use.

bnickel · Oct 21, 2008

i would imagine he's sending the head out to have it worked on because of the bent valve, most likely they'll cut the valve out because if you try to pull a bent valve out of the head it will mess up the guide. i think i would be asking comp for a complete new set of springs, if one spring failed with no obvious signs of damage then most likely more will fail from the same cause eventually

69gmachine · Oct 22, 2008

mrmustangman357 said:
sounds like comp cams need to make this up to you - bad

why does the head need to go out? did it mess up the seat? You should be able to pop a new vale in and hand-lap it then ur done.

but at a min. comp cams should "comp" you a new valve and a full set of springs, locks, retainers. . .

POST PICS TOO if ya got em

I expect the valve guide will need to be replaced. Even if it's still OK now, it won't be after removing the bent valve. Seat looks OK, but until the valve is out I can't really do a good inspection.

10secgoal said:
How close to coil bind?

It shouldn't be anywhere near coil bind. The cam is XE282HR-12. Max lift is .574. The spring binds @ 1.23". Installed height is approx. 1.88", although I haven't mic'd it to be 100% certain. That allows for .65" lift, plenty of room. The engine went through at least 6 dyno pulls after assembly. I haven't been to the track since installing it this time, and I was just cruising home at around 2400 rpm when it let go. I'll try to take some pics.

woodsnake said:
Did you measure for correct pushrod length?

Yes.

ForceFed70 said:
If it's a 69/70 block, you need shorter pushrods

It's a D1AE block, which is the taller 9.503 deck height. It cleaned up at 9.488. The pushrods are the stock length for the '94 roller cam engines, which is much shorter than the regular flat tappet pushrods. The pattern on the valve stem was about as close to perfect as I've ever seen.

I would expect that if it was a geometry issue, more than one would have failed, and it would have been when the engine builder hit 6K, not 1500 miles later when I was just cruisin' but thanks for the ideas. I'd like to figure this one out so I don't make the same mistake again. Right now, I still think it was the spring (Comp Cam part #26120) My mistake was not leaving well enough alone. I replaced the OEM installed springs in the belief that the bee hive springs would survive an over rev better.

mrmustangman357 · Oct 22, 2008

69gmachine said:
My mistake was not leaving well enough alone. I replaced the OEM installed springs in the belief that the bee hive springs would survive an over rev better.

the bee hives couldnt survive a normal rev better

any pics of the damage?

68GT500KR_Vert · Oct 23, 2008

Curse of the engine builder

69gmachine · Oct 25, 2008

68GT500KR_Vert said:
Curse of the engine builder

I think you're right! Thanks for making me laugh anyway.

I took pics of the piston damage and the broken spring, but the head was already shipped out. It took forever to load just the piston picture on Cardomain, and the site went down before I could get the broken spring picture loaded. At the moment I can't get into Cardomain at all, so I can't link to the pictures. I know there are other picture hosting sites, but I'm too lazy to open another account.

69gmachine · Nov 2, 2008

the carnage pics

I finally got around to uploading the carnage pics of the spring and piston damage.

bnickel · Nov 2, 2008

youch......

bnickel · Nov 2, 2008

bnickel said:
youch......

actually it looks like your piston to valve clearances may be a little on the tight side, do you happen to know what they are off hand?

69gmachine · Nov 2, 2008

bnickel said:
actually it looks like your piston to valve clearances may be a little on the tight side, do you happen to know what they are off hand?

I didn't clay the pistons as I left that to the engine builder, but I don't think a stuck valve is a good indicator of valve clearance, or lack thereof. If you mean the notch is a little close, it may be because the valve bent and struck it where it normally wouldn't.

bnickel · Nov 2, 2008

yeah i was referring to the valve reliefs. they look a little close to the edge of the valve to me, but you could be right about the bent valve ending up somewhere it wouldn't normally be.

bnickel · Nov 2, 2008

oh yeah, you might actually want to pull that piston and file the edges a little where the valve struck it, especially the cylinder wall side of it, don't want it to scratch or gouge the cylinder.

Shakin66 · Nov 2, 2008

I had a similair issue and am going to throw this out there although I dont think this is it but....Make certain your valve guides are not too tight. I know that wouldnt cause the spring to break unless the clearance was way too tight but I have been down this road and it wasnt a Piston to Valve clearance issue but was instead the fact that the valve was "locking" in the guide once the engine reached operating temp and causing the piston to hit and bend it. I have pics also and did the whole clay & feeler gauge procedures to make sure I was ok there and I was way good also.

ashford · Nov 2, 2008

Shakin66 said:
I had a similair issue and am going to throw this out there although I dont think this is it but....Make certain your valve guides are not too tight. I know that wouldnt cause the spring to break unless the clearance was way too tight but I have been down this road and it wasnt a Piston to Valve clearance issue but was instead the fact that the valve was "locking" in the guide once the engine reached operating temp and causing the piston to hit and bend it. I have pics also and did the whole clay & feeler gauge procedures to make sure I was ok there and I was way good also.

BINGO, i had this happen to me 5 times in succession on a near stock rebuild, the last time it happened i was so pissed off i got the head off and to the machine shop while the head was still hot and had a short one sided conversation with the machinist. in the end i told him to make all the exhaust valves loose and no problems since.

69gmachine · Dec 15, 2008

We've been having some unusually warm weather here lately so I've been wrenching on the car the past several days. I finally started it up tonight, wohoo!! It started on the first try, so I'm stoked. I may be able to make all the events I planned for next year after all.

stonecoldtx · Dec 16, 2008

69gmachine said:
The cam is XE282HR-12.

Hey, I'm putting together a similar combo (393 with AFR 185's--just the next size smaller in each category), and was planning on using that cam.

I wondered what the idle was like with that cam--is it fairly smooth with the increased cubes, or is it still lumpy?

Do you happen to have any sound clips of the idle?

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