i was just reading a post and some one mentioned that if you want to run unleaded fuel you need to get hardened ex. seats installed.... what does that mean.... i have a 302 mexican block with stock heads from the 70's era.... will it not run right with unleaded fuel....?

 

Tetra-ethyl lead used to work sort of like a lubricant and kept the exhaust valve (in particular) from eroding the seat or causing it to recede back into the head. When the lead was phased out of gasoline about 30 years ago, they had to improve the basic durability of the metal instead. I think either induction-hardening or insert seats are possible choices for iron heads.

I think some heads, and some types of driving are worse than others as far as this is concerned.


Norm

 

To my knowledge all "mexican" block 302 were unleaded engines like the one in my wifes 75 302 Mach-I. If you are using pre smog heads you can have hardened seats installed. End of problem.

 

I have a pure stock 1965 Mustang GT Fastback with the original, never been opened with 110,000 miles on it, engine. It runs great on 87 octane unleaded gas. The reason; it had at least 20 years of leaded gas to lubricate the valves and seats and all the other moving parts that the leaded gas came into contact with. As long as I don't tow anything, do a sustained high speed run (a couple hundred miles at 70 or 80 mph) or any other type of driving that can be a strain on the engine, the engine will be fine.
If you do an engine rebuild, by all means get seats that are made for unleaded gas, in fact, I don't think you can get anything but seats and other parts designed to run onunleaded gas.
The photos are from the photographers website. The car is in my garage. The 'K' car is next to it.
Jim

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ok so i have one more question.... well two... do you get the Exhaust seats put in when you get a valve job done?... because i took my bare heads... nothing on them to the machine shop and had them put it together.... so would they have used hardened seats then?

 

that is one beautiful fastback you have there man

will you take me for a ride in it?

 

I use a lead replacement additive designed to overcome the issue of the old "soft" valve seats.
the lead was used as a form of octane boost (dont ask for the chemistry) but a side effect was lead oxide which formed a layer on the valve seats preventing metal on metal wear.

Jim, in your case I'd beg to differ and suggest the protective layer is long gone.

the one i use is called Flashlube - i dont know if its available in the states, but there are probably other additives out there. From all the research i have done, the octane boosters are a waste of money. The VSR preventers (valve seat recession) from reputable firms are apparently effective. I had the heads off about 6 months ago and they appear in good condition.

 

should have done so...in which case ignore my last post!
I'd ask to be sure

 

my dad can tell you all about how lead boosted octane and how the carbon molecules combine to give higher octane

its a pretty boring speech, idk how many times ive heard it [&:]

 

You could run a lead substitute if you have to drive it a lot. If the heads are coming off you can get hardened seats installed, and make sure the proper valves are used. The valve face may not be hardned as well, or could be worn down below the hard coating