My '76 needs new valve seals, you know, embarrassing smoke when starting . My question is :  What should I expect to pay for this type of repair??  I live in upper Michigan and need some member input so  I don't get taken to the cleaners.  

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Well...this all depends on what you do..if you replace just the valve seals with the heads still on the car it doesn't cost much at all..couple hours labor and seals are cheap...kinda band aid fix but will work for a good while if the guides are ok...if you want or the guides need done then your looking at head removal...then there's 2 ways to have it done...knurle the guides oversize or replace with bronze..also..might want to put the bigger valves in it too...this really comes down to how much you're willing to spend at the machine shop...for this price call around and find out what machine shops charge...don't rule out the little guy who builds race engines too...can find some great machinists that way...one word of cation though..if your engine has a bunch of miles on it you may want to just do the seals and be done with it...having the heads done can blow out the rings...meaning more smoke all the time...it really comes down to the condition of the motor as it sits now..or how much money you got!! I know this doesn't hit on how much..but knowing options of repair can give you the info you need to get solid quotes in your area.

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My first parade at Carlisle 2010

I'll second what Rich says about an all new top end possibly causing more problems than it solves.  When my wife and I were dating she had a little Acura Integra that broke a timing belt.  Since it was an interference engine all the intake valves got bent and we had to have the head completely rebuilt with a valve job.  The like new top end caused blow-by past the rings and we started burning oil like crazy - had to add a quart every time we filled up.  Ended up trading that car in pretty quick after that.  I think new seals would be the way to go unless you're looking at least new rings but probably a full rebuild.  

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I just had mine done,and it made a world of difference....no more smoke.The shop that did mine said what Rich about about just rebuilding the top half.Here in Maryland it cost me $200.00 for the seals to be done.

I'm trying to wrap my widdle pea-brain around something here...
How can knurling, or replacing the valve guides cause more cylinder pressure? Knurling, or replacing the guides should have no effect on the compression....or am I missing sumptin here?
True, doing a complete valve job on a worn head can cause problems for the ring sealing on a worn/"experienced" engine, but I'm not getting the deal with just replacing/knurling the guides.
Not tryin to be a jerk or anything...just trying to figure it out. I ain't done any major engine work in years so....


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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

I'm with ya bud..what I was getting at if you deck the heads and put new valves in with new or machined seats..I'm not really a fan of knurling the guides either but thats just me..if the seals were just replaced and thats it there would be no change in compression of course...other thing too if the guides are knurled or replaced the valve seats would have to be fitted or machined to the valves to properly align the valves with the seats which would incur more cylinder pressure.

|UPDATED|6/4/2012 12:19:52 PM (AZT)|/UPDATED|


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My first parade at Carlisle 2010

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

i just did mine on my 76 and it took a lot longer than a couple hours  about 9 hrs  doing it myself parts cost me 20.00  car only has 49000 miles but it sat for 16 yrs  and the seals tryed up hard and brittle its a lot of work

oops

|UPDATED|6/9/2012 8:17:13 PM (AZT)|/UPDATED|

If you do it yourself it is a lot of work.  But most shops will figure it at about 3 or 4 hours plus parts.  The parts are cheap.  Someone may have the book on the time and can give it to us.  If not let me know and I will go down to my mechanic on Monday and ask him.  I will be having him do that job for me anyway.  Finding out what the book says on the time I believe is a better measure.  My guy goes the book for time and then discounts the labor hours for me.  

I replaced just the seals on my C-4 , it was easy . And it totally solved the issue of start up smoke. The biggest challenge is getting the inexpensive tools ,  most parts people are kids so hit a napa or a well established store in your area, get a spring compressor and the hose you screw into the spark plug threads to pressurize the cylinder . Basic hand tools for valve cover removal new gaskets and new plugs because you pull old ones anyway ! Will take about 3 hours a side on average. 

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1980 , ZZ430 , 3.92 rear , 700R4 2400 stall NEW EZ EFI 

THANK YOU !!! to all the folks who replied to my valve seal question . This forum is a great resource for rookies like me. Thanks again!!

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Book shows 6 hours for both sides....prolly pretty close, depending on if it has A/C, cruise control, etc.

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

book time dont mean youll have it done though them plugs are hard to get too. while your in there clean up the valve covers with some paint

If you happen to drop a valve, you can retrieve it w/ a magnet that fits in the valve guide.  Best to run piston to TDC before removing springs tho.

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1973 L-82 4 spd

I dont know how much you like to work on engines, but the easy trick to change out

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1975 Corvette Coupe 

I know this sounds like going against tradition and it makes me a little uneasy. But, we used to put small block Ford valve seals to replace the little "O" ring Chevy seals that BRITTLE & BREAK up because of the high temps all the time. They fit over the top of the valve guide nicely, cost very little, & last a lot longer. You just need to make sure you fit them over the valve stem & they have a good amount of interference when you slide them down. I think we used to buy the 302ci. valve seals (bonnets) for this job. Hey, I know it is against all the unwritten rules. But you will never have to do this job again, I garranty !!!!

Do those "umbrella" type seals allow sufficient oil down the valve guides?

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1973 L-82 4 spd

The umbrella seals are fine, imo. That's all I've ever used. The idea is to keep excessive oil from running down the valve stem into the chamber thru the guides, not to keep any oil at all from getting to the guides. If you think aboot it, the little o-ring type seals are pretty much useless for anything other than lessening the amount of oil running down the stem after the engine is off. With the umbrella type seals, you will still get lubrication oil down into the guides. 

Most engines now have positive seals on the valves, that seal both to the stem, and the guide...


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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

While the only umbrella seals I've seen were on a friend's 66 427, they were a tight fit to the valve stem.  Not sure how any oil could get past them and down in the guides.

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1973 L-82 4 spd

The seals ride on the valve stems...they move up/down with the valve, so they do fit quite snug. Some seals do fit on the guide boss AND the valve...those are "positive" seals. They seal completely, but they are "attached" to the guides themselves, and the valve stems move thru the seals.
The umbrella type seals do allow some oil to splash back onto the underside of the seals, and run down the stem, and onto the guides. Not as much as the cheesy o-rings, of course, but a little...enough to give some lubrication to the guides. 

|UPDATED|8/12/2012 5:19:36 PM (AZT)|/UPDATED|


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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

The kind I saw were the ones attached to the boss and fit tight around the valve stem.  I do remember seeing the other kind at a store now that you mentioned them, just never on an engine.  I can see how they would work better.

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1973 L-82 4 spd