A hurt valve...

[Paul Workman]

Dr. Pete and his assistant Egore (aka AL) pulled my heads apart and discovered one of the exhaust valves had (for lack of a better description) an evacuation of material about 1/2" long and crossing the big angle of the valve.

Cleaning the top of the piston showed no signs of ingesting anything that Pete and I could see. I didn't have my camera with me, but here is where it is.



Pete's going to take it to the machinist and see what he thinks. It is a total mystery, at this point. But!

More later.

P.

[vettn71]

Weird! Any damage to the valve seat?

Jim

[tpepmeie]

Paul,
just a thought, but is it possible debris from your porting work made its way into the cylinder and damaged the valve?
http://www.zr1netregistry.com/forum/...ead.php?t=8027

Todd

[XfireZ51]

Paul,

Was it #8 cylinder?

Todd,

A bit prophetic, huh!

[Pete]

Yes it was #8.

I really don't think it's the little aluminum flakes that done it.

Took the valve to the machinist he mentioned it looks like it was a bad valve job from the get go and thru the years it ate up the valve.

Pete

[Paul Workman]

Originally Posted by vettn71

Weird! Any damage to the valve seat?

Jim

Not that I could really feel. I ran the edge of my fingernail around the seat, but didn't catch on anything nor did I happen to sense any irregularities. The light could have been better, I suppose. Best I could see, it looked OK.

P.

[Paul Workman]

Originally Posted by tpepmeie

Paul,
just a thought, but is it possible debris from your porting work made its way into the cylinder and damaged the valve?
http://www.zr1netregistry.com/forum/...ead.php?t=8027

Todd

No. #8 intake(s) was closed tight. And, before bolting on the IHs, I dabbed the nooks and crannies with a probe with masking tape (sticky side out) until it was spotless. And, I believe Pete is right about an odd sliver of aluminum would not hurt the bore and would no doubt flash into vapor under combustion.

Truth be known, from day one when I bought the car in Nov of 07, it had a little bit of a rough idle - like it was maybe an injector. I drove the car over 600 miles after reinstalling the ported plenum, and it ran strong. It ran strong when I put it up on jacks to install the new headers, etc.

I first noticed a "chit-chit-chit" sound the very instant I fired it up with the new headers. I immediately suspected a header bolt or two had not been torqued down properly, but no such luck. So, in the back of my mind, I kinda have to wonder if I wasn't just now discovering the problem - perhaps made worse not by the added HP and heat that goes with it.

Looking at the blemish on the valve, it almost looks like someone took a grinder and bumped the bevel on the valve. The seat appears on cursory inspection to be OK. So, the mechanic's comment about possibly a bad valve job somewhere in the car's past, might not be too far off the mark!

Whatever...Screw it! Now that the heads are off, I'm gonna finish the porting, Pete's gonna help with getting the valves ground etc, and do the FBI thing...go racing!! I just hope I can squeeze it all in before Sept 26!

P.

[XfireZ51]

Originally Posted by Paul Workman

Not that I could really feel. I ran the edge of my fingernail around the seat, but didn't catch on anything nor did I happen to sense any irregularities. The light could have been better, I suppose. Best I could see, it looked OK.

P.

Given the possibility of a bad valve job, will you be checking all valves?

[Paul Workman]

Originally Posted by XfireZ51

Given the possibility of a bad valve job, will you be checking all valves?

The plan is to install bronze guides and seals in all the exhaust ports and to have a full valve job done...just in case! But! as long as the heads are now stripped, I might as well finish the porting and be done with it. THEN I'll be ready for the US41 games (provided it all comes together in time!).

I've never done head porting before. But, I have taken the measurements off of Kevin's heads which were originally CNC'ed from Pete's heads. (I coulda taken some pictures, but then Pete would have to kill me if I posted them)...Pretty interesting stuff!! (No wonder that 350 of his is such a killer!! Some real "FBI" stuff!! )

Well, wish me luck!

P.

[Locobob]

You gonna do cams too Paul?