Thread: 429 Help Please. It's A stumper

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Thanks for the lead explanation.
Isn't it amazing that the engineers chose to pollute the planet rather than harden the valve seats?

Originally Posted by DennyW

You would actually need to know the month of that 1970. In 1970, is when they installed hardened seats. That was do to running higher temps for emissions. So, that engine may very well already have hard seats.

So with the hard seats I can leave the iron heads, correct?

Originally Posted by NightHawk

So with the hard seats I can leave the iron heads, correct?

If you have hardened seats you can run the iron heads with unleaded fuel, but if you opt for aluminum you can push your static compression ratio about one point higher without needing to boost the octane rating. The aluminum heads will dissipate heat faster, transferring heat of combustion to the coolant more efficiently, and if you're careful selecting the new aluminum heads you'll likely get improved flow, too.

Originally Posted by firebird77clone

Thanks for the lead explanation.
Isn't it amazing that the engineers chose to pollute the planet rather than harden the valve seats?

When you consider that they won't even add 50 cents worth of nickel to an engine block to make it stronger and last longer, it should come as no surprise that the car makers refused to harden valve seats.

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Originally Posted by DennyW

You would actually need to know the month of that 1970. In 1970, is when they installed hardened seats. That was do to running higher temps for emissions. So, that engine may very well already have hard seats.

Generally, 1970 is the line in the sand for "Induction" or "Flame" hardened seats. Seat inserts were not installed into cast iron heads (that I have ever seen) unless they were diesel or an industrial engine. The factory induction/flame hardening can vary in depth, and can quite possibly only be as little as 0.002" thick. If a "virgin" head is built, I give the customer the choice, unless I see valve seat recession. If it is '69 or earlier, or has already had a valve job or two, I highly recommend the hardened seat inserts for the exhaust.

For a 1970 motor, the cost of exhaust seats, new intake valves (with chrome stems), exhaust valves (hard tips, chrome stem, and stainless in needed), new guides, 3 angle valve job, and surfacing the heads will be cheaper than not doing it, and having to go back in to do it later.