Taking my heads to machine shop and have a question

[65springtime]

I found a bent push rod on #3 plug and pulled the plugs and #3 plug had oil on it so supect the bent push rod hurt the seal. But I want to have the engine gas friendly to unleaded gas and could not remember when it was you had the machine change to make the engine take the unleaded gas with out put in additive.

 

[robbz28]

You need hardened valve seats for the unleaded gas. Back in the day the lead acted like a buffer between the valves and the seats, now if you dont have them hardened you can run into some issues with clatter and improper valve seating in the future. Now, saying all that, if you have a stock to mildly modified engine, you don't need to install hardened seats....probably just need a good re-working.

 

[65springtime]

Thanks, I knew I needed some new valve seats because where the bent push rod was, the plug had oil on it. The Mustang has the matching# 289 motor but some PO installed 302 heads on the engine at one time for unknown reason. So I will tell the machine shop to install hardened seats. Thanks again

 

[robbz28]

If those 302 heads were made after 1975 (i think) then they already have hardened seats, thats when they started using unleaded gas and catalytic converters, just FYI.

 

[Realmongo]

What is the casting number and casting date on the heads?

 

[horseballz]

Have you figured out what caused the bent pushrod? Did your timing chain give out? A bent pushrod is pretty serious, at least for the fact that it points to some VERY serious event that caused it.
My $.02,
Gene

 

[2+2GT]

The hardened seats are not important on a recreational car. If all you do with the car is cruise night, you'll never wear out the seats.

Amoco gas was lead-free for a century, nowhere in the owner's manual does it say not to to use lead-free gas.

 

[Realmongo]

The builder in town said you only need them on the exhaust side anyway.

 

[Hack]

The hardened seats are not important on a recreational car. If all you do with the car is cruise night, you'll never wear out the seats.

Amoco gas was lead-free for a century, nowhere in the owner's manual does it say not to to use lead-free gas.

This.

 

[rbohm]

You need hardened valve seats for the unleaded gas. Back in the day the lead acted like a buffer between the valves and the seats, now if you dont have them hardened you can run into some issues with clatter and improper valve seating in the future. Now, saying all that, if you have a stock to mildly modified engine, you don't need to install hardened seats....probably just need a good re-working.

back in the late 70s when unleaded gas first came out, hardened valves seats were needed due to the lack of lubrication that was taken away when the lead went away. however these days the oil companies include a lubricant in their additive package in the gasoline so hardened valve seats are no longer required, so save your money.