well this past fall I purchased some used 062 cylinder heads from a scrap yard with the hopes of switching out the stock heads on my 350 tbi small block. Apparently the vortec heads, specifically those made between 1996- 2000ish with casting #'s 062 and 906 are the bees knees when it comes to cheap high performance cylinder heads. From my reading they should give a modest increase in horsepower due to better porting and combustion chamber design. As well compression ratio is also increased due to different combustion chamber design, all good things when running on wood I assumed.
So I got these heads that looked relatively decent, no apparent cracks in the normal places (between cylinders or around hold down bolt holes) and heads are straight up to 0.002. I did a hydro test when I got home (pouring water in the intake and exhaust ports to see if there were any leaks at the valves. Only a very very small wetness around some exhaust valves, intake valves all were fine, no water, these were also pretty rusty as they had been sitting for a while without oiling etc. That all seemed good so I took off the springs and did a garage valve job on both heads. Valves turned out real nice, I don’t know what they look like new but i’d say they look pretty darn close.
Getting to the point of this thread, after re-valving 6 cylinders on the 7th while doing the exhaust valve I noticed a small hairline crack (see pictures). I was pretty disappointed to say the least. I finished the head since I was so close to finishing but now am wondering if I just have to trash the cracked head or will this small crack make a difference, can it be fixed? I have more time than money in these heads but would like to use them if able. I can’t tell if the crack goes through to the water jacket, once I get my already ordered valve seals I’ll put the springs on and hydro test them again. There is a local shop that could probably pressure test them as well but just wanted to hear some opinions on this as it my first head job and don’t want to go through the trouble of putting these on and the heads be duds.
I attached some low res photos as well as the high res for those with dial-up
any help is much appreciated
Dustin, I know the heart brake of psoriosis, in other words cracked heads on Chevy V8’s … Usually it is between the valves and you get to see that white smoke every time you start the engine. It was probably the worst with the 400’s. It looks like this crack is both in the head and the valve seat. If they were the last set in the world I would consider grinding and filling in and then re-grinding. I have never replaced a valve seat so don’t know what is involved with that. I have just spun my valves with grinding compound with a drill etc etc … I’d send that head packing as I would never have peace of mind knowing there is a crack in the head. It looks like there has been a migration of metal from where it sat on the gasket. Save it for stud parts etc etc etc … That’s just my 2 cents. Now open that case of beer and hammer a few of them down with some friends … Mike L
You could get the head pin welded and a new seat put in, but I would get a different head if it was mine.
Dustin, The whiteish area in your photos look like there has been steam depositing minerals from the water. I extracted and circled this in a photo but can not upload photos on this site. This is an assumption and may not be the case but as the crack appears to run all the way through the valve seat, I’d treat it as a problem. My real e-mail is mlarosa at mhtc.net so if you want that photo drop me a note direct. Mike
Dustin at least you still have one usable cylinder head. Save this one stripped as a “core” trade in for when you can afford to get another one - this time with a crack back exchange guarantee.
well It hurts to hear the truth but I figured as much. Thanks all for the advice, I’ll have to postpone the rebuilt until I can acquire another head
look into this…as I think your head can be salvaged…you will have to have a new seat installed… they do diesel heads without issues…
look under the repair examples tab and under heads
Hey thanks for the link Dennis. The link you posted has a repair of the exact same problem I have, a crack through exhaust seat. I think I may try and salvage it with the pinning technique, might as well since I won’t be out much it I screw it up