The factory did not install hardened seats. They "induction hardened" the cast iron in the area of the valve seat. It is highly unlikely that your '66 heads have the induction hardened seats. As I recall it was the early 70's when Ford started doing that.
Everything I've read says that hardened seats are not necessary for a mild street engine, even with unleaded gas.

 

1975 is when unleaded gas went into service. Interesting enough back in the early 1920's automotive engineers were encountering the same issues with unleaded gas back then. What they discovered about unleaded gas and valve wear was valve wear was directly related to detonation. The octane was so low back then compression was limited to maybe mid 5:1. If the engine detonated the exhaust valves would have micro welding occurring causing valve seat erosion. If there was no detonation there was no exhaust seat erosion. Entenol was being considered being added to gasoline to raise octane but Thomas Midgley who was a chemical engineer at GM pushed for lead to be added dispute the health risks which were very well know even back then. Many people working on the project including Midgley suffered lead poisoning. Standard Oil was the first to put lead in gasoline for consumer use and many Standard oil employees died from the lead poisoning.

 

The whole thing with valve erosion is due to fuel/detonation/micro-welding of the exhaust valve to the seat. They used to think that TetraEthyl Lead (TEL) was a lubricant, and that's why it prevented the problem. It's been conclusively proven that the reason it helped was because of the octane boost, and not some magical lubricant property of lead salts. No pinging, no problem. Modern unleaded gas is a lot more consistent than the old stuff, so if you tune your engine well, and it's not making enough power to worry about your exhaust valves melting, you should be fine. It also doesn't corrode your exhaust and give everyone lead poisoning.


I wouldn't worry much, if your heads and valves are in good shape.


(ha! You beat me to it Tom!)

 

We need to have a beer together sometime

 

cylinder heads

War, unleaded heads start in 1972, with induction hardening. The valves themselves didn't change but the seats did. If you are not doing a valve job, and it runs well, leave the heads alone. But if you ARE doing a valve job, then add the hard seats, do an exhaust port match, and your heads will perform much better, and be ready for anything. I'll list part numbers for you tomorrow. Your 66 still has regular rockers without rails, yes ? LSG

And if you replace your heads with new aluminum, I want your old iron heads !

 

Thanks for the info everyone.





I don't know my heads need to be redone at all but going to price some aluminum just so I know what my cost would be.



LGS @ yes my rockers are not on rails. I honestly don't know enough about this stuff to really talk engine rebuilds, I can put in parts but picking the correct ones I don't have that knowledge level yet.



I'm still tearing down my 289 but I really want to have all the stuff ordered next week so I can have the engine running before the end of the month if possible. SO trying to think ahead a little.

 

I don't know my heads need to be redone at all but going to price some aluminum just so I know what my cost would be.

LGS @ yes my rockers are not on rails. I honestly don't know enough about this stuff to really talk engine rebuilds, I can put in parts but picking the correct ones I don't have that knowledge level yet

I'm still tearing down my 289 but I really want to have all the stuff ordered next week so I can have the engine running before the end of the month if possible. SO trying to think ahead a little.

With a little port matching, which anyone who can remove heads is capable of doing, you can clean your iron heads up to rival expensive aluminum heads.

"Rail" rockers are not on rails, they have little rails on each side to keep them centered on the valve tips, which are extended for this purpose. This was Change Level 11, introduced as a running change in 1966.

 

cylinderheads

Grim, actually, NO, the chamber shape is not better on an aluminum head. For a 289, the smaller chamber (56 cc ? ) is better. Almost all of the Aluminum heads have a chamber too large for the 289, because the market is geared towards the 302 & 351 crowd. And, don't misunderstand, the Al heads don't 'handle' heat better, they transfer heat away from the burn so fast you have to raise the static compression just to compensate. And, the big chambers frequently give LESS compression on the little 289, which makes the problem even worse. Most289s do very well with correct piston choice and some careful headwork. LSG

 

Grim, actually, NO, the chamber shape is not better on an aluminum head. For a 289, the smaller chamber (56 cc ? ) is better. Almost all of the Aluminum heads have a chamber too large for the 289, because the market is geared towards the 302 & 351 crowd. And, don't misunderstand, the Al heads don't 'handle' heat better, they transfer heat away from the burn so fast you have to raise the static compression just to compensate. And, the big chambers frequently give LESS compression on the little 289, which makes the problem even worse. Most289s do very well with correct piston choice and some careful headwork. LSG

I was referring to the shape of the chamber. Even a set of fully ported '66 289 heads can't match AFR165 Renegades. They come in a lot of different sizes for the combustion chamber, but even giving up a point of compression, I am certain you'd pick up an easy 50 hp or more over stock. The shape of the chamber, not just the combustion chamber volume, has a great deal to do with detonation resistance.


But you're also right that a good porting job and good piston choice can deliver a lot of power even with the original heads! If you can do the work yourself, it's silly not to get all you can out of a set of stock heads.

 

parts

War, please tell me you are not going to order any pieces untill EVERYTHING is apart, clean, & measured ? ....How can you know what sizes you need till everything is taken apart & inspected ? Can I ask where you plan to get the parts ? LSG

 

Yes I'm going to measure and get everything fully apart before I order anything.

As far as where I'm getting stuff not sure yet. I have been looking at summit and jegs online but no decision yet.