[gp64389]

These questions may sound stupid. I've rebuilt plenty of motorcycle heads, but never automotive heads.

I recently purchased a set of "rebuilt" #76 heads off ebay. I got them and they didn't look too clean, so I decided to investigate. The valve seats still had lapping compound all over them.

They supposedly had new valve guides installed. The exhaust valves looked like they might have had new press-in guides installed, but I can see no parting line where new intake guides were installed.

As far as valve stem seals. Exhaust had some ratty looking rubber seals. They came off really easily as if they might be worn. Intake had no seals. Is this right?

New valve seats would require some machining and new seats to be pressed in, right? I can see no parting line to indicate that another piece was ever pressed in.

The combustion chambers and valves are clean, and overall, tolerances appear to be within reason. I've got a feeling that I'm getting the shaft here and these heads were never rebuilt. Any answers are appreciated.

The heads were fairly clean

[gp64389]

These questions may sound stupid. I've rebuilt plenty of motorcycle heads, but never automotive heads.

I recently purchased a set of "rebuilt" #76 heads off ebay. I got them and they didn't look too clean, so I decided to investigate. The valve seats still had lapping compound all over them.

They supposedly had new valve guides installed. The exhaust valves looked like they might have had new press-in guides installed, but I can see no parting line where new intake guides were installed.

As far as valve stem seals. Exhaust had some ratty looking rubber seals. They came off really easily as if they might be worn. Intake had no seals. Is this right?

New valve seats would require some machining and new seats to be pressed in, right? I can see no parting line to indicate that another piece was ever pressed in.

The combustion chambers and valves are clean, and overall, tolerances appear to be within reason. I've got a feeling that I'm getting the shaft here and these heads were never rebuilt. Any answers are appreciated.

The heads were fairly clean

[samssuperpro]

Sounds like you might have gotten shafted. The first thing you need to do is take them apart have a machine shop check them out most shops won't charge you much if they are apart. You need to know if the springs are new they can lead to the most problems,and have them maged for cracks. Hope this helps you if you still need info reply back i'll be more than happy to help you Good luck!

[gp64389]

I knew that the springs weren't new from the start. I planned on replacing those as they could lose some force over a 40 year span.

I need to know specifically:
Does every valve have a stem seal?

To replace a valve seat is the old area machined out and a new seat pressed in?

What do the valve guides look like? Are the old guides machined out and new ones pressed in during a replacement procedure?

[Jeff Walker]

Originally posted by gp64389:
I knew that the springs weren't new from the start. I planned on replacing those as they could lose some force over a 40 year span.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>I need to know specifically:
Does every valve have a stem seal?<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>

Yes, the original style seal is a small rubber sqare cut o-ring that fits on the lower groove of the valve. Some years did have a positive style that fit over the valve guide on the intake valves.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>To replace a valve seat is the old area machined out and a new seat pressed in?<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>
Yes, thats how it's done

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>What do the valve guides look like? Are the old guides machined out and new ones pressed in during a replacement procedure?<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR> <HR></BLOCKQUOTE>
Correct again! There are a few different styles of replacement guides. Some are a thin bronze sleeve, a spiral threaded bronze type, a bronze insert, and a cast insert. Generally the exaust guides will wear more than the intake because of the heat.

As was posted earlier your best bet is to take them to a machine shop and have them checked out to see what you got.

[Mr. P-Body]

"Shafted" may be a pretty strong word. You're only shafted if the individual you bought the heads from had a clue what he was doing. This is one of the areas we have so many problems with, I would LOVE to see some sort of certifying or sanctioning body to establish EXACTLY what "rebuilt" means. To one, it means lapped valves and new seals. To another, it means new parts and ALL machined surfaces showing ANY wear, are refaced. The latter is what it means in MY shop...
We get people trying to sell us cores all the time, telling us the parts "were just redone", thinking that should add value. It does not. In fact, it makes them worth less, unless the source of the "redone" is known, AND known to be good. This is because we, as a shop, must redo the stuff to our specs, if we're to be expected to honor any sort of warranty.
You (anyone, not just this case) are almost ALWAYS ahead, if you simply buy cores (usually with a guarentee of no cracks), and build them. As a machine shop owner, the arguement could be made that I'm just trying to generate work. Not true. I'm trying to help you guys avoid having to pay twice to get something done.
If the price on e-bay seems to good, it probably is. Unless they are asking more than it costs to rebuild something, it is NOT rebuilt. Do the math...