Smoking C1 finale

[Don Izzo]

I pulled the head on my 60 this weekend and found several things. The valve seal on the no. 1 exhaust valve was destroyed. There was heavy oil on this valve as well as one other valve stem who's seal appears ok but still has to be disassembled. There seems to be evidence in each cylinder of leaking oil around the valves. This is surprizing to me as there is only 200 miles on the heads with all new components. When I had the heads originally rebuilt about 1500 miles ago, I had an "unleaded gas conversion" done which included new hardened exhaust seats and new guides installed. He also cut the guides for late style PC valve seals. I had no problems for the first 1500 miles until I broke three of the old original reused valve springs. I gave him bck the heads for repair with all new components except replacement of the already new guides. 200 miles later and I am smoking! I am now wondering if either he reamed the guides for extra clearance, or if the hardened valve seat installation is the problem. I am bringing the one head to a new machine shop today to have it disassembled and gone over. I don't trust the original machinest with the job, and want a second opinion on his work. Anyone have any experience with the hardened seats you care to share?
Don

[Jack H.]

Re: Smoking C1 finale

We routinely cut hardened seats into all the cylinder heads that go through the shop (both SB and BB) without a problem. The typical 'bite' comes from an unskilled machinest cutting the seats in improperly with water jacket leaks into the combustion chamber...

[Don Izzo]

Re: Smoking C1 finale

Thanks Jack, I didn't know how common this was, was a little afraid it was Voodoo mechanics and a difficult thing to do. My mechanic tells me today it is routinly done and not that complicated a job. I think I just have a valve seal problem.
Don

[Dave Suesz]

What kind of guides? *NM*

[Don Izzo]

Re: What kind of guides?

cast iron guides, don't know the brand .

Don

[Dave Suesz]

I just wondered

whether they were iron, and didn't want to ask a leading question. I have had poor experience with bronze in the past, and have always used iron since.

[Dick W.]

Re: I just wondered

I have had good results with the K-Line bronze guide inserts. Secret is following directions for installation

[Joe L.]

Re: Smoking C1 finale

Don------

Your situation sounds like "deja vu" to me. You're heading down the same path I once did and, believe me, it's a path to total frustration. I tell you that not to scare you, but to PREPARE you.

First of all, there is absolutely no connection, whatsoever, to the installation of hardened valve seats and oil burning. They are totally unrelated. So, we can eliminate that as a source of the problem right away. For one thing, hardened seats are only installed on the EXHAUST valve seats. The oil burning problem is related to the INTAKE side of things.

Second, I doubt that there is a valve guide problem. If the guides were replaced with new cast iron guides, especially the type with internal ridges (looks almost like threads), these will perform extremely well. This type guide was originally used on Oldsmobile "Rocket" V-8's and is "tried-and-true".

If the valves were replaced or if the stems were checked for wear and found within acceptable range, then I'd say there's no way that you have a problem with oil getting past the valve guides due to either of these reasons.

I've not had good luck with Perfect Circle type all teflon seals. However, they should really work ok. I assume that by "seal failure" you're talking about the failure of one or more of these. If so, they failed only because they were installed improperly without sufficient clearance bewteen the valve cap ("retainer") and the seal (at maximum lift) OR they failed simply because the valve springs broke and "things went to hell from there".

I'm surprised that the valve springs would be re-used. I'd NEVER reuse valve springs in a rebuilt head or engine. Get yourself a new set of valve springs of stock specifications. These are easily and relatively inexpensively available in the aftermarket or from GM.

For valve seals, I recommend all Viton seals. I've found these to be the best for a street engine. Easily available. Get ones that are sized to fit your currrent valve guide OD (as cut down for the PC seals used). You really don't need them on the exhausts. For the exhaust side, just use the stock, o-ring type seal INSTALLED PROPERLY.

Make sure that your engine has the metal valve spring shields in place. These are necessary for good oil control on a street small block Chevy. Some machinists delete them, especially if PC seals are installed. Use the Viton seals WITH the shields.

Doing all of the above is a good idea. However, I'll bet that it won't solve the oil burning problem one iota. Even with perfect valve stems, perfect oil seals, perfect valve guides, and installed shields, the next time you remove the intake manifold (and, there WILL be a next time if you're persistent and committed to solving the oil problem), you'll find the backsides of the intake valves all "gunked up" with carbonized and wet oil deposits.

So, how to solve it? I wish I knew. I spent hundreds of hours and 1,000s of dollars trying to do it. It even became an obsession with me for awhile. It finally wore me down, though, and, after having been "down every road I could think of", I gave up. I may know more after I autopsy that engine someday, though.

[Clem Z.]

if you use a spiral wound type guide liner

you MUST use a positive type of seal because the sprial groove in the guide liner is a direct oil passage into the intake port. solid guide liners can use a umbrella type seal and they are the best for street engines. if the valves still have the double groove,one for the keys and one for a "O" ring i would always use the "O" to keep excessive oil from running down the valve stem and overloading the seal

[Joe L.]

Re: if you use a spiral wound type guide liner

clem-----

The type I am talking about are not really a "spiral", at all. I just used that term to roughly describe what they look like. They are more like "concentric" raised rings; there is no spiral. The "gooves" between rings ensure that there is always a supply of oil to the valve stems, but do not allow much oil to pass through the guides.

[Don Izzo]

Re: Smoking C1 finale

Joe, The valve springs were replaced 200 miles ago, along with all new valves and retainers. The metal valve spring shields were long gone when I got the car. I have the heads at a local speed shop That I used years ago for boring Harley Cylinders when I had a Motor cycle repair shop. He also recommended the metal valve shields when he saw the heads.
He knows the shop that built the motor and won't bad mouth the guy because as it turns out he does a lot of the heavy machine work for the guy. In point of fact he told me that he very probable bored & honed my block and line honed the mains. He told me that the original rebuilder only did the heads and the reassembly.
His initial thought is that perhaps the inner valve spring is rubbing the PC seals used, causing there rapid deterioration. but he is going to disassemble the heads and check everything. Everything! I don't want to pull these heads again!
Don