Dirty Valves

[GreenMachine]

   These are from a 30,000 mile 440 engine that was rebuilt 8 years ago. They are the stock valves from the Edelbrock Performer RPM Heads. It looks like the valve stem seals are leaking, but they all appear to be in excellent condition and still pliable. Can this be caused by cheap gas? I usually get gas at 7-11 because it's only a couple of blocks from my house. Everything else on the inside of this engine still looks new. I wire wheeled them clean, just wondering if I should order new valve stem seals before I put everything back together.

[elacruze]

Those are normal deposits in any engine that isn't driven on long trips, or driven hard.

To avoid them in the future;
1. Put a pint of Marvel Mystery Oil in every 4-5 fillups.
2. Take longer trips at higher RPMs.
3. Mash that dude to the floor through 2 gears at least once every time you drive it (my preferred method)

Valve seals-Yes replace them. They have some miles and very likely they are a little damaged from pulling the valve grooves through them on the way out. And, they're cheap.

[GreenMachine]

  Yeah, I always let it get up to operating temp. before shutting down, and everytime I took it out for a drive, it saw some high RPM's.
  What is a good valve seal, The Eddy heads use 11/32 valves and .530 guides, so I have alot of choices. Are Teflon seals supposed to be the best?

[elacruze]

Valve seals...mmmm yeah...always an interesting subject. Much more complex than most realize.

There are lots of things to take into account.
1. What are your valves and guides made from?
2. How hot do your valves and guides get?
3. What is the stem clearance in the guide?
4. How worn is the guide?

Having Edelbrock heads, you have nice slick valves and guides. at 30,000 miles they're probably not worn out.

The question is, how much lube do your valve stems need? Not enough and they wear. Too much and they contaminate your intake, or if hot enough coke up and sieze valves.

Now that I've posed a bunch of irrelevant considerations, I'd re-install the same style they came with.

FWIW your deposits look more like PCV or piston ring leakage than guides to me. Got a picture of your piston tops?

[GreenMachine]

  Two of the cylinders appear to have some of those deposits. It comes off fairly easy with brake cleaner, but it takes awhile with the wire wheel, it's gummy and sticky.

[elacruze]

That looks like a little oil coming up past the rings to me. If it was PCV, it would be more evenly distributed and make a mess in the air cleaner/entry point. It's highly unlikely that only two valve seals were leaking, and leaking that much-valve seals don't really see much oil volume unless you're at sustained high RPMs.

If you idle around a lot, with a high-overlap cam, you don't get much heat in the cylinder walls. This can glaze the rings and allow oil past them. It's hard to see in the photos, but the diagnostic for oil past the rings is having clean piston top near the cylinder wall where the oil washes off the deposits, maybe 1/4" to 1/2" towards the center.
An outside possibility is that your cam/intake combination is less efficient in those holes, causing more misfires and dirty mixture. You may consider moving the heat range up in those two holes to keep it a little cleaner.

If you're not taking the shortblock apart, I'd do a good hand-lap on the valves and seats, then do a proper leakdown test after reassembly. If the same two holes come up short, it's most likely cylinder glaze. If they all look good, it's possible that the second rings on those cylinders aren't sealing very good.

In any case, though I've done lots of talking (?) these deposits don't look very severe, they just look like the cylinders are too cold to dissipate deposits. Where they come from only matters if you're doing a complete disassembly to fix, and with no changes to your combination/driving style/temperatures you can expect a return to same.

I'd like to hear from some others on their opinions.

[flyinlow]

Not alot of deposits. Clean off .replace valve seals. Drive faster ,try differrent brand of fuel with differrent detergent addatives. Keep a picture of the valve with you to explain your speed to the cops.

[Challenger340]

Not alot of deposits. Clean off .replace valve seals. Drive faster ,try differrent brand of fuel with differrent detergent addatives. Keep a picture of the valve with you to explain your speed to the cops.

LMFAO !