I was planning on a cam swap this weekend. So while we were at it the guy at the hobby shop says to me, lets test these heads out. So we run some compressed air through the spark plug holes and wow did they leak bad. So I pulled the heads off and SEVEN of the valves are shot. They were seated flush in the heads. This was an ebay buy, with a 'just rebuilt motor, less than 1000 miles!' Price was real low though so I can't complain too much. The block looks clean and it WAS rebuilt. The cam was worn and pitted, looks like it wasn't hardened properly, the lifters all dished, the timing chain gear all notched up and worn, the valves wiggling back and forth in the guides... It's like it was rebuilt and then they put back in the same worn parts! I went in for one little thing and found all this other S***.

So now I'm not sure what to do. I had been considering a swap for a 383 or a LT1. But that was gonna be a swap, build the motor then swap when it was done. But now that I have everything apart I just want to get her running again. It already looks like it will be Feb. before I can afford new heads. Too much work to make any sense rebuilding them. For the same price I could buy some new ones. The bottom end looks fine from what we can tell but it's still in the car. Should I just pull that too while I'm at it? Might be cheaper to just build a screamin little 350. At least I already have a four bolt block. I'm so frustrated and ticked off. I'm glad I found the problems so that I can fix them and fix them right but DAMN!! Looks like a lot of down time.
-CR

 

You may also be able to get some money back from eBay or Paypal if you paid via paypal.

 

Rebuilt engine: Rings (and bearings, maybe just rod bearings or maybe nothing) replaced. No machining.

Overhauled: All wear components replaced or remachined to make the engine "as new."

eBay rebuilt engine: Hit it with some spray paint.

 

CR:
Sounds like you got a little wet ... but maybe things aren't so bad. You say you were about to do a cam swap ... that indicates the motor was not running so bad.

Are we to assume it was not smoking oil ... and not rattling noticeably ... and oil pressure looked ok?

If yes to all ... then things probably not too bad; if so ... have the heads serviced w/ fresh Z28 springs ... new timing set & cam & lifters ... roll in a new set of rod & main bearings ... maybe a new oil pump if old one's gears are nicked ... all this won't be but 2-3 hundred more if you've already got the cam&lifters and you're doing the disassembly-assembly.

When the heads are serviced ... don't have new guides installed ... do have them install "thin-wall bronze liners" ... cheaper, just as durable and flows better.

*edit* most '72 350 have 1.94"&1.50" valves ... you can find a full new set of 16 2.02"&1.60" for under $100 ... have them installed when you have the heads serviced ... that'll raise them right back up off the seats.

here's a set of 2.02/1.6 stainless for $80
http://www.competitionproducts.com/p...sp?number=8440

here's a set of same valves with retainers, springs, locks & seals for $130.
http://www.competitionproducts.com/p...?number=851226

 

 

I think that unleaded gas was a thing of the future in '72. I know your engine had been "rebuilt" but if the heads were from an earlier year they wouldn't have had hardened seats. Unleaded gas + miles = valves receding into the heads. Have the heads done with the bigger valves, good seats and away you go. I used Z-28 springs on a 350 a long time ago and had zero problems.

 

GM knew unleaded was coming ... beginning MY1971 exhaust seats are induction hardened; compression ratio's dropped in sbc&BBC same MY.

 

When the heads are serviced ... don't have new guides installed ... do have them install "thin-wall bronze liners" ... cheaper, just as durable and flows better.

*edit* most '72 350 have 1.94"&1.50" valves ... you can find a full new set of 16 2.02"&1.60" for under $100 ... have them installed when you have the heads serviced ... that'll raise them right back up off the seats.

here's a set of 2.02/1.6 stainless for $80
http://www.competitionproducts.com/p...sp?number=8440

here's a set of same valves with retainers, springs, locks & seals for $130.
http://www.competitionproducts.com/p...?number=851226[/QUOTE]

but I would pull the block & have it checked out while your at it & install a new clutch & flywheel.

 

Gerry- Sorry it wasn't just an eBay motor. It was the whole car. I did get reciepts with it though. The block was bored .030 over. Other than that it's hard to tell what was done.

Jackson- The motor was running OK. No smoke, no alarming noises. A clicking sound that rose and fell with the RPM's. Thought it might be a stuck lifter. We guessed that #8 wasn't firing. When we pulled the 8 plug from the distributor, it didn't change the RPM's at all. Also got backfires on the right side when decelerating. Other than that it seemed OK.

The block is original but it turns out that the heads were not. For a 72 there shouldn't have been part numbers on the heads, correct? But there definately were. I have access to tools and knowledge but not the machines for any work. It looks like I might be better off buying some new heads. The valves all had a lot of play in them in addition to being worn. Probably gonna pull the motor too. I'm much calmer and a bit more rational than I was yesterday. I'd really rather not pull it but I want to do it right. Thanks for the tips guys.
-CR

 

Under valve covers ... in amongst springs ... are are raised, cast-in numbers ... those are head casting numbers ... and a date code. Quite likely '72 sbc head casting number ends "487" or 487X". ... Verify what you have & post back here ... same with the date sequence ... someone will interpret for you ... also post your car's build date. From that it can be reasonably determined if heads are a likely match.