Iron head question for builders

[wowens]

Hard seats or not ?
Will some heads take them and some won't ?
Experiences, good or bad ?

[frnkeore]

I wouldn't have a head w/o, at least Stellite seats in them.

I had a 2 seats burn and drop at least .15 with SS valves. Stellite's, will, pretty much last forever. But, at least, in the early heads, you'll have a step under the seat. I use 1.66 valves, to minimize that.

[Falcon67]

I have a set of 2V 351C heads modified for 2.19/1.71 stainless valves, stock seats with a performance seat cut.  Never had any seat recession issues and ran the hell out of them on street and strip. The 4 V heads in the Falcon - same, no changes in the last 20 years/3000+ passes.  They do usually run on a 50/50 mix of 91 pump/VP100 leaded.

[frnkeore]

I have a set of 2V 351C heads modified for 2.19/1.71 stainless valves, stock seats with a performance seat cut.  Never had any seat recession issues and ran the hell out of them on street and strip. The 4 V heads in the Falcon - same, no changes in the last 20 years/3000+ passes.  They do usually run on a 50/50 mix of 91 pump/VP100 leaded.

That's the point, leaded gas is way different than unleaded. My head was a '71 and ran on nothing but 87 octane, unleaded gas, with the engine loaded a lot, in a PU.

 I built it in '86 and it only lasted about 16 months, before the first valve burnt (just one). I replaced it and then about 3 yrs later is when I had them burn and drop, out of sight.

[blykins]

If the engine is going to be loaded hard, like in Frank's example, then I would recommend putting seats in the heads.  If it's a cruiser, or a toy, I typically don't.  There can be core shift present on factory heads and I've seen some heads ruined by putting seats in.

[manofmerc]

All I can say is my 390 powered 66 f250 had all eight exhaust seats recede they were c- 8 heads I used it as a daily driver and to pull a utility trailer with welding equipment .It was used to pull my race car as well .After new seats and a valve job all was good.Doug

[pbf777]

If the engine is going to be loaded hard, .......... then I would recommend putting seats in the heads.  If it's a cruiser, or a toy, I typically don't.  There can be core shift present on factory heads and I've seen some heads ruined by putting seats in.

     +1   

     But remember the latter, particularly with valuable castings, as Ford Motor Co. did not cast these heads with the intention of the capability of receiving seat inserts, and even a capable machine shop has no control over the quality of the casting, and can make no real preliminary observation as to the survivability in the operation.       

     Scott.

[My427stang]

Is there any ability to induction harden on the streets?  Couldn't have been too tough to do if Ford did it on every D2 head.  Would be neat to toughen things up a little.

That being said, it also depends on valve angles, spring pressure, even how long the valve can cool on it's seat and expected EGT, but I also don't put seats in iron heads unless necessary.

[manofmerc]

Over the past 15-20 years I bought several core engines from pull a part- coworkers and from craigslist.Most of these were common 360 390 truck engines .More than one had hardened seats installed by who ever .The vast majority of these had failed .You could see the seat or seats suspended by the exhaust valves and water damage to that particular cylinder .Lots of heads went to the crusher for these reasons .Most were c-8 or d-2 castings .On my 390 with c-8s I never had any trouble and the fellow I sold it to hasn't had any either .Those seats were installed in 2007 .My current 390 has hardened seats in a set of c-8s so far so good I bought the heads used and since they were used and appeared to have high mileage I didn't think the seats would fail .So far so good .Doug

[pbf777]

More than one had hardened seats installed by who ever .The vast majority of these had failed .You could see the seat or seats suspended by the exhaust valves and water damage to that particular cylinder

      And this is a problem, even if at the time of installation everything looks 'hunky-dory', but down the road, well, ................!        As stated previously, nobody said there was adequate material to support the press-in seat, in this heat & cool, expansion & contraction, with pounding and vibration participation going on.     

      Scott.

[Henrysnephew]

I've had several sets of tunnel port heads over the years and they all had hardened exhaust seats.  Could this have been an OE feature of the t/port?  Randy M

[SSdynosaur]

As I understand, the earliest cast iron version(s) of the Tunnel Port cylinder heads seated the exhaust valves on the parent cast iron material. The "later" cast iron version(s) were machined and fitted with pressed-in, replaceable, hardened steel exhaust seats. I will defer to Dennis' vast FE library to fill in the correct dates and specifications. My source was/is Mr. Buckmaster for the generalities.

[67xr7cat]

If you only going to use it once a month to go to a car show or cruise and put 1,000 miles a year on it likely be ok without hardened seats. If just needs the original seats touched up may be ok. Seems the old leaded gas over use would get to the head metal. if cutting fresh material and going to use unleaded gas and will see some miles or other than light duty use best to have hardened exhaust seats installed.

Now the non-smog heads are not fully supported around the exhaust valve and some feel it can result in a loss of press and a dropped seat.  In all of them you have to use the right seat as is not much room.  Basically you need someone who knows these heads, how to machine them, and what seats use.  Finally once you get new valves, guides, seats, valve job, etc... your not far from just getting an aftermarket head.  Is a guy down in Florida sells iron heads with CJ valves and hardened exhaust seats. The hardware is ok. Been doing it a long time says never had a dropped seat. Can figure about $800 from him. 

[MrRupp]

Why not just run a lead additive in every tank of fuel. That way you don't have to mess with the head. I did that in my 428 CJ in my 76 F-250 highboy for at least 10 years. Drove it everyday, had no trouble at all. Clint