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Discussion Starter #1
It seem that the issue of installing hardened valve seats, is one of the most controversial discussions that I have been following on this sight. For as many people swear by them, the same number believe that hardened seats are not a good idea. I understand that some of the replacement seats are no better than what is removed... and that the seats are only going to be as good as the shop that installs them. I have read about how great Stelite seats are, but also horror stories about valve seats comming loose, and potentially destroying a new engine. Some believe that they interfere with the heat disapation in the heads. It seems that for every "expert" who favors hardened seats, you will find an article by another "expert", who strongly discourages using hardened seats. Some say that you will destroy the exhaust seats in no time, if you dont install them. Others say that they have been running their high RPM engine for ever, without hard seats, without a hitch. I have read that you only need them in engines that are used hard, for towing, racing and such. Those who believe in them, swear that they should be installed on every motor that doesnt have them. It seems that after following this subject for the last two years, its still just as confusing to me as to what is best, seats...or no seats????
 

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I have run with & without. My 429SCJ is stock, my Blue Thunders have a H-13 tool steel exhaust. I'm on the fence on this one.
 

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My big HP 351C 4V does not have hardened seats ...

My information is that as long as you know for sure you will be running high octane fuel at all times, it won't make a lick of difference.
 

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Who says they are bad? Anything, when done wrong, is bad. Certain engines like the BBF can't take very deep seats or you'll hit water. If you run the appropriate press they won't come out. Usually they are used because they HAVE to due to seat recesion anyway. We have them in iron headed circle track stuff and they never come out. Shops that have this problem don't know what the hell they're doing is what I'd say.
 

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I've run with and without them and beat my engines up a bit. Never had any problem with either, but I also don't put 10K miles/year on my classic car.

What I have been told, and you have probably heard this one, is that over time, the unleaded fuel will cause the exhaust seats to wear quicker than (properly) upgraded seats. How much faster? Who knows.

I've also been told that it's sustained highway speeds over time that wear old seats the fastest.

My $.04 (someone else's $.02 with interest over time)
 

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I rebuilt cylinder heads for four years, installing hundreds of seats in that time, and never had one fall out.
If installed properly, they will not fall out, will dissipate heat away from the seat, and flow just fine.
The only time I have seen inserts fall out, has been on aluminum heads that were overheated.
Every aluminum head has seat inserts on both intake and exhaust seat, so they cant be that bad.
 

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I wouldn't fool with hardened seats. They can be more of a burden than a blessing. Here's a little information on the subject from Dave Williams... who is a very trusted machinist.

http://www.angelfire.com/ar/dw42/seat.htm

Here's his whole site.

http://www.angelfire.com/ar/dw42/

Plenty of GREAT reading here. You could spend hours letting your brain soak up all sorts of cool info.

Personally, a friend of mine took his fully ported cast iron Chevy heads to the machinist and had seats installed. When carving out the head for the seats, they cut all the way through to the water jacket. When he installed the heads, they leaked. The cylinder got all pitted up with rust and the head was junk. It was not a good experience.

I've got 9 years of hard use out of the 289 heads on my car... and no, they have not had hardened seats installed. The valves are not excessively recessed either.

Tow vehicles that see high loads for extended periods of time are about the only thing I would consider installing TRUE hardened seats in. I would rather start with later model heads that already have them.

Short periods of high load or rpm do not cause seat recession... and that describes 99% of all hotrods.

Good Luck!
_________________
Mike Burch, 66 mustang real street
302 4-speed 289 heads, 10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367

<font size=-1>[ This Message was edited by: n2omike on 3/25/02 9:38pm ]</font>

<font size=-1>[ This Message was edited by: n2omike on 3/25/02 9:46pm ]</font>
 

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Yes, like I said, you have to known what you're doing and iron heads have more water and have water between the seats than aluminum does. If you know the head you're working on, installing seats are fine and can actually AID the valve in losing heat.

This is why they are used on high load engine and turbos and come on a lot of marine and airplane stuff. Cast iron will not remove heat nearly as well as some of the copper based hardened seats will. It's the same with guides. Iron guides are crap for performance in general and don't suck heat out nearly as well. The valves run hotter and therefore need bigger clearances with iron guides and iron seats. You can take up substantial stem clearance when you switch to non-iron stuff becuase of the heat reduction.

As N20 Mike said however you have to run much smaller OD as well as shallower seats than you would in aluminum due to the closer water jackets because if you do break through you usually have to junk the head. The big block Mopar and big block Ford are known to be hard to put exhaust seats in because of no short side support for the new seats so you have to run very shallow seats and smaller OD than you might want to keep out of water. It CAN be dangerous on those heads.
 

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Any of my daily drivers will have hardened seats for sure. I put at least 40 miles a day on my torino, with almost every weekend going up and back to stockton a couple times (140 miles there and back). My dad had a mgb, without hardened seats. It was his daily driver, to work and back, trips and all. The seats wore fast, had to adjust the valves often, until they couldn't be adjusted any more. He wouldn't install hardened seats, but ended up replacing the heads 3 times over 10 years. Having the seats coming loose, or cutting into a water jacket isn't because hardened seats are bad, its incompetent machinists installing them. Installed correctly, hardened seats dont wear as fast when you dont have leaded gas, or lead additives to lubricate and cool the seats. For the people who don't drive their cars all the time, you probably dont need hardened seats, you dont drive your car enough to notice the difference. For people who drive their cars often, you should seriously consider hardened seats next time you have your heads off.
 

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Discussion Starter #10
Typically what will it cost to have hardened valve seats installed, using good quality seats?
 

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Locally ... Here in Vegas

I think it's around $325.00 ... This would cover all aspects of the "valve job" to prepare it to head back to the street.
 

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Discussion Starter #12
Are there any earlier stock heads that already have the hardened valve seats and smaller cc-chamber for small blocks? Also, does anyone know when Ford started using hardened seats in general?
 

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I had hardned seats installed on my heads, they weren't that expensive. Especially if you are getting the heads re-worked anyway.(this was by a reputable shop too)

The seats cost $40 (8 of them)
The install was $56
The valve grind was $100 (for all valves)
This included deshrouding work too.

I believe the hardned seats where standard about 73???

Hope that helps
 

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Its been a while since I've worked on heads, so I dont remember exacly what year they started hardening the exhaust seats. But I'd guess around 73-74.
 

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Factory heads use "induction hardening" which is a heat treating process. They are not 'inserted' seats like you'd see in aluminum heads. The induction hardening process is only so deep, so if the head has had a few valve jobs... the seats might not be hardened any more.

The automakers started doing this when unleaded gas became mandatory in 1975.

There are no small chamber 'unleaded' factory heads.


Unless you have some serious hard use (towing) planned for extended periods of time, hardened seats are not needed.

Good Luck!
 

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Mike,

Actually some iron heads do have hardened inserts in them but not many. Ford marine and high load industrial have a type of sintered copper alloy insert and I've seen BeC in some iron Mercruiser stuff!
 

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actually, I've installed hard seats in my 460 heads. They were quite easy with a tcm25 seat & guide machine, so easy in fact that it's pretty hard to screw up. Never hit water even when I opened up the bowls to match the 2.25" intake valves. We just cut the head to the size of the insert, put a little j-b weld on the insert (sparingly,just to make sure), and installed the inserts. Took about an hour to do all 16 valves. They arent too bad to cut a seat on, either. Way I see it, if a machine shop screws them up, they have no idea what they're doing, either that or all that beer from the night before hasn't worn off yet.
 

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Discussion Starter #18
Mavman...thats interesting about the mention of applying a dash of JB weld. The stuff really works great and fixes just about anything, but would that have any negative effect on the seat over time? Has anyone heard of a machine shop using any type of epoxy, that can be applied to the bottom of the seat just for a little insurance?
 

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There's no substitute for the correct machining and installation of hardened seats! I'm not sure what the heat transfer characteristics of JB weld are, but might be a little leary of it.

Aluminum heads have been using seat "inserts" for a long time... If they were that bad, it would have more press than the GM diesel did in the late 70's!

I have some OEM experience with head manufacturing, but not a lot with aftermarket. Know that the tooling to make the correct seat bores can be expensive....

From a different angle, it's a good way to save some heads that you've put time and $ into.
 
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