Hard Exhaust Seats on a 390 FE Motor

[1969_Mach1 333]

I know this has been discussed before.  First of all I am freshening a 390 that was built back in about 1980.  I was only driven about 200 miles and has been parked since about 1986.  I am now in the process of installing new valve springs and valve seals on the cylinder heads.  I am using springs Comp suggested for their hydraulic flat tappet cam I am installing.

Here is the issue I have come across.  When the these heads were rebuilt back in 1980 hardened exhaust were not installed.  Of course back then pump gas still had some lead in it so the valve seats look just fine.  Are hardened exhaust seats really needed for a car that might only see a few hundred miles per year?  I get conflicting information on this.  Some say Ford's castings are a harder alloy so it's not as critical as GM castings.  Any information is appreciated.

[barnett468 418]

You absolutely do NOT "need" hardened seats in your particular case unless you have fairly high valve spring pressures, I guarantee it, however, if any of the seats are sunken in, they should be replaced with new seats. One of the problems with the chevy's is that some people put huge cams in them with high spring pressures and this causes the seats to wear prematurely, especially if their engine is not tuned properly, which it often isn't, and when their valve seats go bad, they blame it on the head material instead of their own ignorance.

Also, installing valve seats is an art which I am familiar with because I ran the cylinder head rebuilding department of a big machine shop for a while, and if they are not installed properly, they can, and sometimes will fall out, especially if an engine gets hot, like around 210 degrees or more, and I have had them fall out of the heads in 2 cars I had bought before, and in one case it broke the piston.

 

[barnett468 418]

I figured I should ad the following as well.

Alcohol can cause premature valve failure because it is "dryer" than gasoline, so the more alcohol there is in gasoline, the sooner the valve seats will wear providing the fuel mfg's did not add a lubricant to the fuel to counter the effects of the alcohol, however, it may be difficult to determine if they did, so one option that can used to lubricate the valve seats in engines that have non hardened seats is to add a lubricant to the gasoline, and there are some products that claim to do that, but they also have other additives which shouldn't be a problem because these products were designed to be added to fuel, however, if one wanted a product that was primarily a lubricant that was designed to be mixed with gas for the sole purpose of lubricating it, one can just add some 2 stroke oil. I would use the least expensive mineral based 2 stroke oil I can find and start with a ratio of 150:1. Yamalube S is a common one, and at 150:1, it should only cause a very small amount of smoke, if it causes an at all, and you could even mix it at 200:1, but obviously the lubricating effect would be reduced some.

None of these products will reduce valve seat wear as well as TEL (lead) which you can still buy and use as an additive if you want, and many racing fuels and aviation fuels have lead in them, and it is legal to run, but it's just not really eco friendly, plus you don't want to get it on your skin because it can go thru it into your blood stream, but it would take a lot of repeated exposure for it to build up sufficient toxicity to cause a problem.

Here's a short list of fuel lubricant/additives, of which some are also claimed to be fuel stabilizers, fuel stabilizer product, so I have no personal experience with them.

Power Zol by Lubrizol. They make the oil additives that most, if not all the automotive oil mfg's in the US add to their base oil.

Sea Foam

Soy Plus

 

 

 

 

 

 

 

 

 

[1969_Mach1 333]

Thanks for the information.  It's pretty much similar to everything I've read, hard seats are not so critical on cars that are only occasionally driven.  Red Line makes a lead substitute that looks good.  It claims to not cause any valve sticking issues like other lead substitutes.  And the mixture is small, 1 oz. per 10 gallons of fuel.

[Rsanter 152]

You do not need hard seats on a low use engine.

not having them will only shorten the life of the valve job by 10-15%