valve job

I bought a 64 Riviera that has a a burnt exaughst vale but other than that, its a running car. I plan on taking the head off and taking it to my machinist.

What do I need to tell him to do for this ? I was going to do a valve job with new galve guide seals. He wants to put in hardened seats but I seem to remeber reading that 1. You dont need them 2. if they put them in, it cuts into the water cooling area.

Is this true and what do I need to watch for so I dont trash a head.

Thanks

 

Dont put in hardened seats, unneccessary expense. in all my years of messing with nailheads I have never heard of one burning a valve. rare.
Dont let them ''sink' the valve pocket to narrow the valve seat. ''raise'' the seat by using a stone down in the pocket to bring the valve seat into spec.
Check close, if the valve is actually burned, to find out why.

 

After reading posts in the middle of the night last night (too much mexican food for a late dinner) I found information about doing the valve job on this board. Now I wonder if I do have a burn't valve... I am going by what my mechanic told me. Normally he doesn't try to get money from me extra as he gets enough as it is.

What I have is a pronounced ticking from the drivers side valve train. It sounds like the first cylinder in that bank. Could it be a lifter ? If I do a compression check it should show if I have valve problems.

This motor sat for 27 years and now its running great except for this noise...

 

More information and a question or two...

I did a compression check this morning and all the cylinders except the noisy one have between 150 and 170 lbs. The noisy one has 30 lbs. I squirted oil in it and it is still at 30 lbs. So it sounds like a valve problem to me.

I have a pair of heads that I pulled off a running motor after it put a rod through the cylinder wall. Same casting number and it was a425. Do you think it is safe to just stick another head on there ? How could I tell before I put it on, if the head is any good ?

Thanks for any help.

Bill Stoneberg

 

Woodenbuick.......it sounds like perhaps a valve is sticking. As for hardened seats, that's a definite no-no on a Nailhead. You WILL trash the head unless you are very lucky. Also, burned exhaust valves on a Nailhead are extremely rare.......it could have been caused by severe overheating. There's really no way to tell until you actually take it apart and find out what's going on in there.

 

I'd pull your original head, and find out where you stand- could be the head, could be a piston- you'll know either way real quick- could be a valve sticking - you'll only know by pulling the head...

 

So I have the head off, no hole in the piston and the valves look good.. Nice and tan for the exaugst valves.

So how can I tell if one is burnt ? It really doesn't look like on is toast but I may be missing something. How can I tell if one is sticking ? None look open after taking the rocker arms off. The top of the valve looks different on the noisy cylinder though...I was going to pour some solvent in the chamber and see if it will stay in the chamber or leak out.

Thanks

Bill

 

Looks different how? sounds like a weak lifter , bent pushrod, weak spring or bent valve on that cylinder. noisy leads me to lifter or pushrod...good luck...

 

Burned valves get really hot, and usually appear to be cleaner than the others. Very little carbon, b/c the heat burns it off. It may appear to have a gray color, normal color may be tan. What makes it get so hot is the hot exhaust gasses leaking past the seat, which could be from it sticking in the guide......possibly other things. Either way, you'll need to have both heads done up.

IMHO, don't replace the guides, sleeve them. Some of your original guides may be non-concentric, replacing them with new concentric ones will throw off the spring seats. The valves will end up deeper into the seat pockets, and everything will be out of whack.

Be sure to stay away from hardened seats.....Carmen has a cutaway view of a Nail head, and it's amazing how close the water jacket comes to the exhaust seats. When you cut the opening for the new seat, even if it doesn't break through, the casting ends up super thin in that area......not a good thing. :Smarty:

Good luck

 

break the valves down on the suspect cyl. look at the faces and the valve seats. highly possible that you have a lifter that is not pumping up at all, especially after sitting up for so long. pull the lifters on that cyl and look at the surfaces that mate to the cam. If they are cupped , look at the cam lobes. If the lobes are ok then replace the lifters. also check out the push rods,rocker arms, and rocker arm shafts.

 

I poured some gasoline into the offensive cylinder head and the one noisy cylinder, it leaked right out past one of the valves while it stayed put on the other 3 cylinders. So something is wrong with the way its seating. Dont have the tools to pull it apart though.

Looked at the pushrods and rocker arms and see no visible damage. I am off to my machinest tomorrow to see what he finds.I in the meantime will clean some of the accumulation of dirt off so I can get the valley pan off.

Thanks for all the help today and the suggestions on what to check.

One more question, where can I get a steel head gasket to replace the one that was on it ?

 

[check.

One more question, where can I get a steel head gasket to replace the one that was on it ?[/QUOTE]

try www.classicbuicks.com

bob m.

 

Thanks Doc for the dood suggestions... After taking it to my machinist, I discovered my valve and seat were rusted and pitted beyond repair, because as they were trying to repair it, they found a crack in the head by that valve. We are assuming that is what let water in to rust the valve.

I also checked my rocker arms and need to replace a few as the steel pades were gone and the pushrods were beating the aluminum to death.

So I found a good head and am getting all new lifters for that side. I have some spare rocker arms and will change those.

 

Here's what scares me here.......if that head was cracked, and water rusted a valve seat, it sounds like it froze and cracked. I can only wonder if the block may be cracked somewhere too? You may be much better off just rebuilding the whole thing and magnafluxing the block rather than trying the piece meal approach. Just a thought.......good luck :TU:

 

Hi Bill, let me give you a "tip" now for what it's worth. With ALL the damage you've mentioned you ARE going to do an all-out rebuild in the near future. Trust me on this one, it's not "if", simply "when"!!

All the metal "floating" around the unit more than likely has "contaminated" both the bearings AND most definitely the cam, lifters, and rings. This includes the cylinder walls also. This won't be an enjoyable unit to deal with "down-the-road".

I would recommend examining every area inside while it's opened up.

I hope I'm "out in left field" somewhwere, but I do this all day long for a living!
The way you've explained it all, I see a short-lived future!

(Add) With respect to the valve seat inserts, this is becoming a very "major" issue with these and other "thin" cast heads. As the alcohol content of the fuel climbs the seats are going see more "wear & tear". These heads, the Nailhead, along with the early Hemi's, and numerous others don't lend themselves to inserts very well. They all can be set up for unleaded, but it's another entirely different procedure altogether. It involves "laying" a nickel bead in the seat area. Unfortunately at this time I personally can't do them anymore with the "nickel" welding method.

Thanks, Gary in N.Y.

P.S. Remove the lifters one at a time and examine the bottoms, there should be a slight "roundness" at the surface. Lay some sort of straightedge on there and see if they're still "convex". It's also not good practice using new lifters on an already broken in cam. Many will argue this point but if we use new lifters, we use a new cam. The risk outweighs the benefit of a "lifter-only" change.