Vader

(Time for a new page...)

You certainly can't beat a leakdown test for diagnosis. When seven cylinders range between 8.5% and 13% leakage on a cold engine, and the eighth leaks at 95%, it doesn't take a rocket scientist to isolate the problem.

Guess what the exhaust valve looks like on a bad cylinder, compared to a new one:

ChevyKen

iTrader: (1)

Hey Vader,

We made it back just fine!

Yeah, that valve was bad, and I've been thinking about it today - Im almost a bit surprised that the seat didn't take more of a beating from it? If it had not been for the piston that doesn't show any sign of contact - I would've thought that must have happend recently. But as you said, it would've had to hit something and it obviously wasn't the piston.....

Oh well! Im looking forward to hear what you find out at the machine shop - and most of all, Im looking forward to hear my baby purr again before too long


Ken

V8Astro Captain

iTrader: (1)

How does something like that happen?...so I know NOT to do it

8Mike9

Sure that's not one of those canted valve heads?

99Hawk120

Was there any damage on the corresponding piston?

ChevyKen

iTrader: (1)

We couldn't see any damage at all to the piston - so the assumption is that this happend when the heads were installed on a previous engine. Our guess is of course also that this has been one of the main reasons for all the trouble that we've been chasing in the previous 4(?) threads that we've gone through regarding my car on this board over the last 3-5 months...

Currently Vader is waiting for a set of injectors and a set of roller rockers to arrive before putting the rest together.

Vader, did you get the pics of the cam spec card last night?


Ken

BMmonteSS

I had the same exact problem with a set of "good" heads i bought off a "buddy". There was a bent valve on both heads one intake and one exhaust. I found the exhaust valve real quick but the intake valve took 2000 miles to start leaking. A top end tear down and one less "buddy" later and the prob was fixed.

Vader

Mike, As a matter of fact, I think it might be. It "CANTED" have possibly run right with that valve in the head.

Incidentally, Comp ground the cam 1/2 degree off (retarded), or my coat hanger wire isn't calibrated. I couldn't have installed the degree wheel a half-degree off, could I? Not ME!

Degreeing the cam showed it was off by 17.75°. If you do some simple math with the tooth counts on the crank and cam sprockets, if the chain set is installed one tooth off, the difference should be about 18°. Guess what I found when the timing cover came off? You can't blame the installer, since the crank gear was marked oddly. I got the auto center punch out and fixed that, too.

zroc

yup... that will do it... cool... glad you guys got some results...

Ken, what does the interior of a death star look like??? lots of cool stuff to play with??? give Vaders dog a pat on the head for me...

zroc

8Mike9

Wow, I'd blame the installer (Ken) ...just because.

BTW, I have a calibrated coat hanger in the closet...if you suspect your may be going bad.

Vader

Mike,

I may take you up on that calibrated coat hanger, as long as you don't want too much for it. Do you have the cert that indicated NIST traceabilty, or will I have to have the calibration checked? Otherwise I'm hitting eBay and I'll get one there as long as the bidding doesn't get stupid-high.

And as for the timing, you can blame anyone you want, but the crank sprocket was marked "NO", presumably meaning "Normal" about a half-tooth from the smaller, more obscure "dot" that is supposed to be used as the alignment indicator. Too bad the photos don't show it more clearly, but if you zoom in you can see a little of it. As I stated earlier, the "dot" was actually a small circle that was barely stamped in the face of the sprocket. Aside from that, the marks on the crank sprocket didn't match the installation instruction sheet provided with the timing set. Great, huh?

I can understand the confusion, and it's another reason I'm not really hot on the "three-way" crank sprockets. Other kinds of "three-ways", well, that's a different story...

Besides, I know you were just jerkin' his chain a little.

8Mike9

Ya....just a little yank'en.

Good news for Ken is that you were willing to take a shot at it...and it paid off.

Funny though, about the valve...I wasn't aware he was using used heads, I thought he bought them new?

And also yet another reason to degree in the cam, especially when you're not doing this type of thing on a daily basis...heads would have still have to come off I guess if they were bad when installed.