Head grinding, hard seats or not?

[Domenic T.]

In another post Ridge brought up a point and Iwould like to share with you as to what I learned about the effect of un-leaded gas on the valve seats.
I have a lot of engines that I am still using that I did not use hard seats in when I ground the valves.
I also had teen age boys that drove some of my cars and caused a few unexpected tear downs. I was also able to rebuild my chevelle again after 180K on the engine and the seats I ground only needed to be cleaned up a little with the stone, an easy gring.

I have had no problems using unleaded gas. New chevy heads were built new during this time without hard seats and some say that the cast iron was hardened around the seats. Couldn't tell it by me when I ground them. If you grind valves a lot you know what I am talking about. One can tell how hard the seats are by the sparks, time, and how many times he has to dress the stone.
A well known shop said that I was getting away without using hard seats because I initally used leaded gas durring the break in and the lead impregnates in the seats as sort of a seat break in. He said he uses an additive for a few tanks of gas and it impregnates the seats so you can use un-leaded fuel.

I use SS valves in my high compression engines but also the regular ones in my other engines and so far so good , many years with no problems.

If you don't need seats then don't have them installed is my thinking.

DOM

[Clem Z.]

Re: Head grinding, hard seats or not?

In another post Ridge brought up a point and Iwould like to share with you as to what I learned about the effect of un-leaded gas on the valve seats.
I have a lot of engines that I am still using that I did not use hard seats in when I ground the valves.
I also had teen age boys that drove some of my cars and caused a few unexpected tear downs. I was also able to rebuild my chevelle again after 180K on the engine and the seats I ground only needed to be cleaned up a little with the stone, an easy gring.

I have had no problems using unleaded gas. New chevy heads were built new during this time without hard seats and some say that the cast iron was hardened around the seats. Couldn't tell it by me when I ground them. If you grind valves a lot you know what I am talking about. One can tell how hard the seats are by the sparks, time, and how many times he has to dress the stone.
A well known shop said that I was getting away without using hard seats because I initally used leaded gas durring the break in and the lead impregnates in the seats as sort of a seat break in. He said he uses an additive for a few tanks of gas and it impregnates the seats so you can use un-leaded fuel.

I use SS valves in my high compression engines but also the regular ones in my other engines and so far so good , many years with no problems.

If you don't need seats then don't have them installed is my thinking.

DOM

AMACO no lead white gas has been around since the 30s before all this about no lead gasoline causing valve seat erosion. if it still worries you put in a couple tank fulls of 100LL av gas to put lead on the seats

[Domenic T.]

Re: Head grinding, hard seats or not?

Actually Clem thats the fuel I have used for years and thats the leaded fuel I use to keep my vette engines original inside also.
I can tune them to what the book says. and enjoy the high compression and original sound they make.
As far as I'm concerned the engine was the car back then (not discounting the beauty)because there were many good looking muscle cars but guys bragged about having a VETTE engine in their car.
I was a little taken back to find that there are so many guys that want to see rust and bad paint here & there but think nothing of changing the compression & cam to burn todays gas.
One said that these old cars don't do so well light to light but I strongly dissagree. A simple 327 with solids and good fuel I have makes the Jap toys look bad. yeah I will get some coment on what ones think will kick but on the older cars, but they did run.

[Joe R.]

Re: Head grinding, hard seats or not?

Dom,

The wisdom I have seen on here more than once says that you probably don't need hardened seats to run unleaded gas. Valve seat recession is caused by running sustained high rpms (pulling a boat, etc). Since most vintage Vettes aren't used for that sort of duty, no need for hardened seats!

Joe

[Michael W.]

Re: Head grinding, hard seats or not?

Dom,

The wisdom I have seen on here more than once says that you probably don't need hardened seats to run unleaded gas. Valve seat recession is caused by running sustained high rpms (pulling a boat, etc). Since most vintage Vettes aren't used for that sort of duty, no need for hardened seats!

Joe

Exactly- in addition to high RPM, a high load on the engine is also required to develop the extreme valve seat temperatures that lead to material loss and transfer. Corvettes never run at these conditions long enough to experience such problems.

[Duke W.]

Re: Head grinding, hard seats or not?

if it still worries you put in a couple tank fulls of 100LL av gas to put lead on the seats

True - the lead oxide film or whatever it is that forms on the valve seats tends to be long lasting, so breaking in a fresh engine with 10-50 percent 100LL avgas or equivalent will last a long time and you can add some leaded gas every few thousand miles.

But, if you don't do this, you will likely never have early seat recession problems in normal road driving.

Duke