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  #1  
Old 08-01-2018, 11:23 AM
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rang-a-stang rang-a-stang is offline
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Hardened seats or Stainless valves?

I dropped my heads off at the machinist today for rebuilding/blueprinting (babywag gets to laugh because he warned me this was going to happen).

I am building my engine to last about 150k miles so the machinist recommended installing EITHER hardened seats (on the exhaust) or stainless exhaust valves. In another thread SC/397 recommended these stainless valves to someone else:
Ebay, 16 Stainless valves

The also sell just the exhaust valves
Ebay, 8 Stainless exhuast valves

I think it would be cheapest to just order this set and have the machinist install them on the standard iron seats. If that's the case, should i spring the extra money and do all stainless or just the exhuast ones?
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Old 08-01-2018, 12:27 PM
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79 motor? Are your seats showing obvious signs of regression? Shouldn't cause by 79 the seats should already be unleaded compatible. If were mine I'd have a proper refurbish done on the intakes and spring for new exhaust valves. Your call if you think you need "new" intake valves? Whether brand new motor or rebuild you can expect at some point in the next 150,000 miles to do a valve job. For optimum performance occasional valve jobs are normal maint.
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Old 08-01-2018, 01:07 PM
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rang-a-stang rang-a-stang is offline
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My truck is a 79 but the heads are not. My heads have casting number 3216090-1 which google said is a 1973 casting. I have not had them disassembled yet but I had decent compression when my engine was still together and passed CA smog just before tear down so I assume they were decent.
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Old 08-01-2018, 01:46 PM
joe joe is offline
 
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Don't fret the 73 heads unless valve seat regression is obvious. IMHO the 1974(?) Chicken Little the sky is falling and all our motors are going to blow up w/o lead in the gas turned out to be a major crock of chit rumor promoted by machine shops. That's regarding normal use street cars/trucks, not race motors. Freshen up your existing heads to spec and go drive...
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Old 08-01-2018, 05:58 PM
440sixpack 440sixpack is offline
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If you want maximum engine life hard seats are required. the factory didn't go with hard seats because they needed to get rid of unwanted cash they did it because they're required. VSR is very real and not just some marketing scam . I've seen it too many times.

On low performance engines not used hard you can get by for a long time without them. especially if you use a higher grade fuel and set your timing correctly. does this mean you don't need hard seats ? that depends entirely on your expectations. most experts say figure 60k rather than 100k as a rule. do you feel lucky ? you decide.


Stainless valves will not compensate for soft seats. but they're better than doing nothing.


Anything worth doing is worth doing right. hard seats are doing it right. if you're just trying to get the last gasp out of a POS then I can see not spending a few extra bucks but that's about it.
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  #6  
Old 08-04-2018, 09:34 AM
wiley-moeracing wiley-moeracing is offline
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or save up a few more bucks and by the aluminum Edelbrock heads and be done.
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Old 08-04-2018, 10:49 AM
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The valve seats were induction hardened from the factory after about '72. Even in 1966 the heads and block were made out of casting with a higher nickel content. It would be rare if a seat or two was wore enough to justify new seats. Your machinist should be more worried about the guides being wore out.
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Old 08-04-2018, 12:34 PM
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Quote:
Originally Posted by rang-a-stang
My truck is a 79 but the heads are not. My heads have casting number 3216090-1 which google said is a 1973 casting. I have not had them disassembled yet but I had decent compression when my engine was still together and passed CA smog just before tear down so I assume they were decent.

It's always best to tear down & inspect before you bring them in.
Some shops aggressively push the "full monte" and want to spend a lot of your $$...many times it just isn't needed on a mild street build.
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Old 08-04-2018, 05:06 PM
fsj454 fsj454 is offline
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Heads

What I did to my stock 1990 heads. 4 exhaust valves and guides and seats .New springs and seals .resurface head .Machine shop fee total out the door 350.00
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  #10  
Old 08-05-2018, 12:18 AM
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rang-a-stang rang-a-stang is offline
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Quote:
Originally Posted by babywag
It's always best to tear down & inspect before you bring them in.
Some shops aggressively push the "full monte" and want to spend a lot of your $$...many times it just isn't needed on a mild street build.
Totally. good info. I called him and asked him to tear them down, send them through the cleaner, then call me and I will head out there and check them out with him. I wouldn't say he is "pushing"; he just knows I want this motor to last a long time so he says "should" alot. Kind of the same thing 440sixpack is saying. my problem is i'm tapped out. I want to do it right but can't really afford it.
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  #11  
Old 08-05-2018, 08:34 AM
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Just because you don’t do everything brand new doesn’t mean it’s not “right”.
Nothing wrong with reusing valves to keep some $ in your pocket.
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Old 08-05-2018, 11:55 AM
Ristow Ristow is offline
 
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if the valves are not pocketed now i wouldn't bother with hardened seats.


you're gonna need exhaust valves,almost surely. the intakes should be fine. go with stainless on replacements. cast iron guides and positive seals. and call it done.



tell the machinist to grind the new valves. they are not always ground true. been there,done that,took it back apart and did it again.....



i'd go all new myself.



as far as long lasting,lets get real here. very few here will put 100K on their fsj.
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  #13  
Old 08-05-2018, 02:25 PM
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All good stuff. Thank you, everyone. I found this thread today and the OP pretty NAILED everything I am reading.
Ford Muscle discussion on hardened seats
I am going to see how the seats look once they are opened and cleaned. if they need replacing, they will get replaced but I am not going to replace seats that can be serviced.

Quote:
Originally Posted by Ristow
as far as long lasting,lets get real here. very few here will put 100K on their fsj.
Very true. Honestly, I might, though. I am building this one with the intent of road tripping it often. When we move to Boise (hopefully next summer), I will be 6 hours from my brothers in law (Portland), 6 hours from my parents (Reno), and 6 hours from my son in Utah. I expect my oldest son and his family (my first grand baby) to move to Utah in the next couple years, too. I would rather drive my Cherokee to go visit my family than my Mazda because it is MUCH comfier. If I add a 4 speed auto and gears it should get better MPG than our Pathfinder (~16 mpg highway) and not much worse than my Mazda (about 24 mpg highway).
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  #14  
Old 08-05-2018, 05:27 PM
Ristow Ristow is offline
 
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Quote:
Originally Posted by rang-a-stang
Very true. Honestly, I might, though. I am building this one with the intent of road tripping it often.




take it from a guy thats been in alot of these motors,and daily drove one for years for a 104 mile round trip......if you do put alot of miles on it won't be the valves/seats that start giving you trouble. they'll be the least of your problems come 150K miles later. i really doubt you will be running seat pressures or a cam thats gonna be hammering the seats.

if the valves and seats can be cut without pocketing a valve,than do so.
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  #15  
Old 08-05-2018, 11:02 PM
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Haha! Good point! I love it when reality smacks you (well, actually me) in face!
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  #16  
Old 08-06-2018, 04:08 AM
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FSJunkie FSJunkie is offline
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Install hardened seats

The first engine I rebuilt was the AMC 232 I6 from my daily driver. I was a sophomore in college and taking engine's class that semester. I decided to rebuild my own 116,000 miles engine for my class project.

The professor advised me of course, as did the owner of the local machine shop. They had 80 years of experience between them.

I wanted to install hardened exhaust valve seats and new valve guides. They were worn and I knew I needed this engine to handle lots of interstate driving. Both of my advisors said this was unnecesary and that the engine would "probably be fine" if I just reground the original seats and left the guides alone. I followed their advice and built my engine as they told me.

Fast-forward to my senior year, 15,000 miles later. Cylinders start dropping compression. I determined it was from leaking exhaust valves, so I pulled the cylinder head off my brand new engine and sure enough, those exhaust valve seats were pounded out wider than the valves themselves, recessed back into the head, and oval-shaped because of the worn guides. Not sealing worth a darn. Now I was pissed off. Fortunately I was taking advanced engines that semester. I carried my 60-pound cylinder head into the college machine shop and did what I should have from the beginning: installed hardened exhaust seats and all new guides. I also installed all new valves, all new springs, all new keepers, and touched up the intake seats. I cut no corners. I put $300 into that cylinder head with top-quality materials and I did it all myself because at this point I didn't trust people any more and I was pissed.

That engine has run fine ever since.

I put hardened seats in everything after that fiasco. I learned the hard way. I'm also more skeptical of advice now and trust my own judgement more.
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  #17  
Old 08-06-2018, 07:11 AM
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Take it from a guy who has built a few of these engines.. LOL!
Seriously, In 160 cylinder heads I can only remember cutting and installing new exhaust seats in one pair of cylinder heads that had been reworked once already. We have never had to replace the intake seats. This includes all of the cylinder heads casted before they started induction hardening the seats. Sometimes the valve stems wear out and valve guides wear out but even this is not near as common as other makes engines of the same time period. Like mentioned above, even brand new valves will have to be ground to match the correct angles etc. Make sure the machinist laps the valves to assure a good 360 degree seal at the right contact width. Another key thing to look for is cracks in the cylinder heads at the front and rear corners. This is much more common than having to replace valve seats.
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Old 08-06-2018, 08:58 AM
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SC/397 Would you go with valve guide inserts the machine shops seem to be pushing these days or replace with new cast iron guides?
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  #19  
Old 08-06-2018, 10:30 AM
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Quote:
Originally Posted by levelhead
SC/397 Would you go with valve guide inserts the machine shops seem to be pushing these days or replace with new cast iron guides?




Great question. If you have to replace them, the machinist that I have used for the past 20some years prefers cast guides on a street engine. He is picky and also polishes some of the stainless valve stems because they are kind of rough. He told me that he hasn't had to do that to the stainless valves that I have given him. He also hones the guides to get the correct clearance. Not all machine shops do this.

I an now using a second machinist and he likes to use bronze sleeves. I asked him about that and he says that he has never had a problem with them - whatever that means.



I am not a metalurgest but maybe a stainless valve would play nicer with a bronze bushing and a non-stainless valve would play nicer with a cast guide. I honestly don't know.


Rambling on here and sorry, not answering your question directly, I have been leaning towards in putting positive type valve seals in everything. I usually use the nylon umbrella seals on stock stuff but sometimes those seals don't fit the valve stem tight. It costs more of coarse but may be worth it in the long run.

Last edited by SC/397 : 08-06-2018 at 10:43 AM.
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  #20  
Old 08-06-2018, 10:42 AM
wiley-moeracing wiley-moeracing is offline
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I always cut the valve stem so I can uses the better valve stem seals, lasts longer and a less oil leakage. I would just do a quality valve job and pay attention to the valve guides. The hardest part is finding a good honest machine shop now. Kind of like finding a doctor, when you do stick with them no matter if it costs more.
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