DC Valve Guides

I was having a conversation with a friend today and we talking about repairing valve guides. I asked him if there was a way to repair a guide without removing it. If I remember right he said sometimes a intake guide can be repaired removing the valve spring and replacing the seal.
Is there such a seal on a DC head? The only difference I see is a chamfered end on the exhaust guide
 
I have spent a lot of time looking for umbrella seals to fit the D engines. I have not been able to find a seal that fits the valve stem size, and still fit over the large diameter of the valve guide. If you were willing to press the guides out and turn the top end of them down you could find a seal to work, but then you have to start over with grinding of seats. If your guides are a little loose they could possibly be knurled, but that takes removing the head and valves.
 
Valve guide seals came to life in the 70s, with emissions legislation. Guides would pull oil around them, to lubricate the valve stems of course, but some would get in the combustion chamber or the tail pipe and result in Hydrocarbon pollution. Guide seals where an effort to prevent that, early ones starved the guides and the the ex, due to heat, would wear very quickly. Some stems have o-rings around them to prevent oil running down the stem. Most engines, with iron heads, from the 50s into the 90s had integral guides, cast as part of the heads and machined for the stem. As they wore, several practices evolved to restore them. The most common, was a simple knurling tool, followed by a reamer. Tightened them up nicely while leaving space for lubrication. Another system was called bronze walling, where the guide was bored out to make it round and straight and then a thin wall bronze sleeve was installed and either reamed or, the preferred method, honed to proper clearance. Obviously this type of repair required the head to be removed. These practices could also be used on pressed in cast iron guides. Some prefer it. These are the same ol Ford/Chevy type of discussions, but worked very well. Your own experience, or that of your local machinist is your best guide.
 
I seem to remember (I could be dreaming of course) there was a tool that would machine the outside of the guide to a dimension that would accept the good stem seals (sealed power ?). The tool may have been K-D or Lisle possibly a cutter on a valve guide machine. Check with a machine shop that does heads. In your area Sturdy in Milbank, CNC in Brookings, Hedahls, ect. I think you are in eastern SD.
 
Be aware though, that these engines were designed to pass a bit of oil to lubricate the stem and the guide. I've seen guides that were sized to tight, maybe in the .0015 range seize when hot due to oil starvation. Oil is a real inhibitor to combustion, as it really lowers octane can hurt power, so it should be controlled, but a guide umbrella type seal on a worn guide is just a crutch. Our old, very low compression engines can handle a bit of oil, but it usually manifests itself in fouled spark plugs. I feel the best, is a reconditioned or new guide, properly sized, and no guide seal.
 
(quoted from post at 09:36:56 01/30/17) Be aware though, that these engines were designed to pass a bit of oil to lubricate the stem and the guide. I've seen guides that were sized to tight, maybe in the .0015 range seize when hot due to oil starvation. Oil is a real inhibitor to combustion, as it really lowers octane can hurt power, so it should be controlled, but a guide umbrella type seal on a worn guide is just a crutch. Our old, very low compression engines can handle a bit of oil, but it usually manifests itself in fouled spark plugs. I feel the best, is a reconditioned or new guide, properly sized, and no guide seal.

Bronze walling the guides is a very acceptable fix, the guide is enlarged and a bronze sleeve pressed in and sized. bronze is a great bearing material. A competent machine shop can rep-air the guides.
 
Here is one way to repair guides with a liner.
https://www.goodson.com/blog/2012/01/installing-classic-valve-guide-liners/

There is another way too with a spiral wound spring. Something like a heli coil
only different.
 
Thanks guys for the info.
I probably will be pulling the head this fall giving those valves and guides a makeover.
In the meantime I have access to a three bottom plow and to give the DC a workout.
 

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