Rickman48

Are they really necessary?
Having read many people paying to have hardened seats installed, why??
Granted, it's been awhile since doing headwork at busy shop, [late 70's] but I never saw a 'torched' seat or valve in probably 500 sets of heads!
This includes some high-mileage commercial trucks all the way to Top Alcohol motors but mostly high-performance GM '60's heads, as we did a lot of work for other speed shops in Chicagoland.
Stainless vaves were initially the answer for unhardened seats.
Guess my question is; has anyone had burned valves or seats on todays fuel??
My thoughts are; the manufacturers started this in the early '70's to compensate for the 'lean years' and continued on because of unleaded fuel - unnecessarily!

matt69olds

I have heard that the government did some testing back when lead was being phased out that unless heavily loaded at sustained high rpm the valve wear isn't an issue. The C heads on my 87 Cutlass have been run hard on the track and probably 30K and still going strong.

joe_padavano

X2. If you are having the heads done, it's good insurance to put the seats in, but if you have a running engine, the only real difference with non-hardened seats will be reduced valve job life. You might go 60,000 miles instead of 100,000 miles, for example.

Rickman48

Then WHY are some people, even today, recommending hardened seats, especially to newbies??
It's not cheap, and could even stop some projects!
Most of these cars won't see 60k after a rebuild, let alone 100k!
Unnecessary recommendation, in my opinion!!
Pocket porting would be more adventageous, and money well spent!
After all, efficiency means more horsepower!

64Rocket

I don't do it unless it is a daily driver and driven hard with lots of miles.
The '71 and '72 heads have induction harden seats and that is good enough.
Gene

Coltonis

Interesting you mention induction hardening.

I was just thinking instead of machining in a separate piece of harder metal and then shaping it into a valve seat in a head, what about just tempering the already cut seats directly? So apply heat to the local area of the valve seat then quench the heated metal.

I assume "induction hardening" would be creating the exact same tempered result only using some induction heating method instead of, oh say - a blow torch? Or, is that not right?

Would the heat needed to accomplish the tempering dis-form the seat?

Warhead

No, they are not necessary.
NO reputable shop in the Phoenix area will warranty a set of heads without them, and there are PLENTY of examples out here, of exhaust seats down as much as 1/4 inch.
A buddy brought me a set of late model, induction hardened BBC truck heads (peanut ports) with 3 exhaust seats down .100"- .200". The lifter does not even have that much travel. It just keeps going away once it has started.

Things that affect this---heat and loading on the engine.

Talk to a machinist in your area for their opinion.

Ask Jim at J&S machine for his opinion---he does exhausts, and intakes on everything.
http://www.jsmachineoldsmobile.com/

Jim

Texas Jim

Warhead,
You said, "No they are not necessary." Then said that no reputable shop will warranty heads w/o the hardened seats. Are you saying that the hardened seats are the correct way to go, or that the shops are beating us by making us get the hard seats in order to get a warranty? Thanks in advance.

Rickman48

I believe the 'induction hardening' process woud have one of the first procedures done at the factory, maybe even when they were still hot from casting.
After cooling, I'd think there woud be more of a chance of cracking or warpage.

That was initially my point - why, especially on a street car??
A lot of shops say it's necessary to replace seats - I disagree, unless it's had 3-4 valve jobs, and the seats are sunk too far, or torched!
Valves and guides are another story - replace as necessary!
Just jacking prices, unnecessarily, IMO!

Warhead

Thank you Jim...

First off, they are not necessary.
I'd rather have them.
The factory originally built them without, there is no law that says you must use them. Your car will run fine, but for how long-
But it WILL happen, eventually. And it would happen even sooner in the hot desert Southwest US, in my opinion. Depends on how deep your foot is in the throttle, and for how long--and at what temp.

Second, GM went to hard seats on all their cast iron heads. WHY? The BBC truck heads came with induction hardened seats, at first. After several years, they went to a pressed in hardened insert for the heavy duty iron truck heads, like machine shops install into older heads. Why would GM go to that extreme, with all of the costs involved?

Third, I said no reputable shop in the Phoenix area will warranty. Shops do not like to have their parts come back for free work, if they want to stay in business. Cylinder heads that come back that can no longer hold compression through a valve is a baaaaaad thing.
They're covering their butts. It's good business sense.

Lastly- I HATE HAVING THEM DONE, MYSELF! I do not have the equipment to do this operation, either. I have to pay for it and it does suck.
So does losing a cylinder, or 2.
So does pushing, and towing.

It's not a conspiracy.
Jim

Texas Jim

Warhead,
Thanks f/ clearing thatup f/ me. Everything considered, I like the idea of having the hard insert. Yes, I do realize that they're not necessary. I like the way Joe stated it; if you're doing the heads anyway, to get them done, but if you have a running engine, not to pull it apart just to have the hard seats installed. I've done afew engines that I left alone, not gone into time after time to make performance modifications. Since I like to do things right the first time, I like the idea of hard inserts when I prepare the heads, however, that's if I plan on leaving the engine alone and not replacing the heads down the road later, and if I don't plan on keeping the heads f/ another engine in the future sometime. Rickman48 made a good point, as I've been there; he stated that the few extra dollars on the hardened seats, that aren't really necessary, really could bring your project (engine) to a hault if you're operating on a budget. He's right. I have done a number of engines on a strict budget. 1.) I love building engines and even when I couldn't really afford it, atleast having to squeeze every penny f/ afew months before and after, I'd do the build anyway. 2.) When I had 2 builds going on at the same time, ie; motorcycle and car. One time w/ engine already built f/ the motorcycle( an 1123cc Wiseco kit, yoshi. cams, Mak.carbs, etc.) and finishing the cosmetics. And the engine I was building f/ a '66 T-bird, an off-set 351W. (used the Windsor as the head bolt holes are further away from the cylinders than the C or any other small block Fords which allowed f/ more of an off-set on the cylinders) I also, in '83, got a set of heads f/ the sbc I was building that were off of a 327 that was in a dump truck, and the 327 had a governor on it. Those heads had hardened exhaust inserts, also had (can't remember the size) small combustion chambers. Warhead speaking of the GM truck engines having hardened seats reminded me of that. But, like I said, the ones I had were inserts.

All in all, Joe put it best; if you have a running engine, leave it as it is. If you're building an engine, and you'll be keeping it, or atleast keeping the heads f/ future use, and you won't be going back into it f/ performance upgrades, get the seats done, "IF" it doesn't hold up your project due to the cost.

Rickman48

Just a 'bump' - current thread running with repeated info -