OjaiM5 HalfDork
3/14/21 9:38 p.m.

I did a compression test on my 454 and the numbers were great (180+) until I got to the cylinder that read flat 0! The car actually ran pretty good and I had no real reason to think there was a broken valve. Pulled off the head and found a chunk missing. 

I am wondering what to do next? I rather not pull the engine, or have to rebuild it if I do not have to. I do not see any signs of a collision between the piston and the valve although it seems like this is what would have caused it. My wish would be to just check the springs and put in a new valve. 

Would love to hear some suggestions.  Thanks in advance.

wvumtnbkr GRM+ Memberand PowerDork
3/14/21 9:49 p.m.

Put in a new valve and send it.


I'm curious if the valve you take out is bent at all.

aircooled MegaDork
3/14/21 10:03 p.m.

I am curious where the piece is.

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
3/14/21 10:05 p.m.

In reply to aircooled :

It went out the exhaust and is now in the cat 

Curtis73 (Forum Supporter)
Curtis73 (Forum Supporter) GRM+ Memberand MegaDork
3/14/21 10:07 p.m.

Replace valve
Lapping compound until you get a good pattern
Bolt heads back on and drive.

stuart in mn
stuart in mn MegaDork
3/14/21 10:17 p.m.

I wonder why the valve broke, and would worry a little about it happening again.

Gearheadotaku (Forum Supporter)
Gearheadotaku (Forum Supporter) GRM+ Memberand UltimaDork
3/15/21 11:07 a.m.

Yep,new valve and go. If it happens again then do the long investigation.

OjaiM5 HalfDork
3/15/21 1:28 p.m.

Thanks for all the input, much appreciated. I am looking forward to using the lashing compound, never done it before. 

I'll tell ya, not fun bending over into an engine compartment to fish out a 454 head. Damn heavy!

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) GRM+ Memberand MegaDork
3/15/21 1:32 p.m.
OjaiM5 said:

I'll tell ya, not fun bending over into an engine compartment to fish out a 454 head. Damn heavy!

That head probably weighs more than half a me!

APEowner GRM+ Memberand Dork
3/15/21 2:59 p.m.

I can't tell for sure from the photo but odds are that valve is burned not broken.  While you've got the head off check the other exhaust valves to make sure that they're still in good shape. 

bigbrainonbrad Reader
3/15/21 3:28 p.m.

It'll buff right out?

TurnerX19 UltraDork
3/15/21 5:37 p.m.

Strong recommend from me to replace all 8 exhaust valves. They were all new together and this one is the first to fail. If it is really burned (doesn't look it to me) then something else probably caused the failure. If broken, the other 7 are going to do the same pretty soon. Look close at the fracture before you decide to just replace one.

mdshaw Reader
3/17/21 9:47 a.m.

Also when you get the valve back in, set the head up on it's side on the intake ports & fill up each exhaust port with gas or diesel. Let it sit all night. Then you'll see any leakers.

WillG80 GRM+ Memberand Reader
3/17/21 10:02 a.m.

I haven't seen it mentioned, but I'm assuming no damage to the cylinder wall? Assuming that's the case, I'd replace the valve and run it. 

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