Re: Valve Guides/valve seats/overhaul/leadedgas


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Posted by Gordon Maney on Sunday, December 17, 2000 at 10:37:06:

In Reply to: Valve Guides/valve seats/overhaul/leadedgas posted by John J Conrardy, D.C. on Sunday, December 17, 2000 at 09:52:23:

Tetra-ethyl lead was added to fuel to boost octane. It had the coincidental benefit of providing a lubricating effect for valve seat and face surfaces. The fact that your engine has a low compression ratio does not create your (potential) problem. The fact it was designed and manufactured during an era that used lead-supplemented fuels, and therefore metallurgical decisions were affected by that, is really the problem.

Although in the broad spectrum of automotive engine rebuilding there are alternative valve guide materials, the valve guides are really not a part of such a discussion as this. The valve seats are the components of primary concern, and to a lesser degree, the valves. I say valves to a lesser degree because valves generally include much better metallurgy.

There is another dynamic that needs to be introduced, since your wish is to do the best you can for your Dodge engine: What machine shop are you using? I spent seven years in technical service for a manufacturer of automotive machine tools used by engine rebuilders. Virtually my entire job was talking to these people, helping them use their equipment, diagnose it, repair it, etc.

What you find is, just like any other area of endeavor, there is an enormous range of competence. I found shops that Ñ literally Ñ did not own micrometers. I found people you would not want to have touch your coaster wagon. But, they have credibility because they are a business with a sign and a storefront. There are some really frightening folks out there.

When you find the qualified machine shop, you can look to them for recommendations on what valves and seats they have available. Compared to some applications in that market, I think this engine is rather limited in terms of what is available. If you deal with a rebuilder that is competent and active in the rebuild of heavy duty (heavy truck, ag, off-road & construction) engines as well as light duty, they will understand the advantages of what ever alternative parts are available.

I think there will only be one cast iron guide available. If there is a solid bronze guide (not a liner), you might use that. Get the best valve seats you can find, for intake and exhaust. Get the best valves you can find for both, as well.

Use forged pistons if you can find them, balance the engine, bore and properly (I canÕt emphasize the word properly enough) hone the cylinders, surface the block deck so it is parallel to the main bores. Recondition the rods and replace the rod bolts. Use moly rings. Replace the water distribution tube in the block, of course replace the cam bearings. Replace the cam and tappets if you can find new tappets. Use a new oil pump and a new water pump. Have your radiator properly cleaned and tested.

Let me repeat a thing here. You have to find a good rebuilder. In dealing with machine shops, I was always interested in talking to the sales people who got into the shops, particularly when they were hiring work for themselves. It was very common for a person to have their work done at four different shops. One had a really good guy doing the valve and seat work, and he also had good equipment. Others did not.

If his valve seat pilots were junk because they were worn, and his employer was a cheap bastard who had the intellectual capacity of a cocker spaniel, you could not get good work even if the man was highly skilled.

The only way you can know where to go is to talk to people who have used them, and nose around to see how things look. Find out who does the work for the serious commercial customers. Talk to the racers in your area, the people who buy engine rebuilding services for stock cars and drag cars. Also talk to the motorcycle dealers for their opinion.

It is not an easy thing, but it is an important thing. I hope I have not made you paranoid, but you must know a bad shop can use all the nice parts you want and come up with a really bad job...



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