hardened valve seats 235 chevy

What years require harded valve seats in the head? How long will mine last without it? Is there any sort of additive I can add to the fuel to hold off on doing this?

The engine is a 235 out of a 63 chevy pickup

 

After a complete rebuild, I've been running a 235 in my '37 Chevy coupe for over 10-years (about 35k miles with a 3.73 rear end) and I don't baby it. I've had no problem with the valves and they're the stock valves & seats. Never used any lead substitute and didn't need it, IMO & experience.

 

I too runa a 235.
It's in my daily driver and has the original valve seats in it. If it's not under a lot of load, the originals should work fine for years.
r

 

you can get a lead substitute at most parts stores. I have a '55 235 in my 50 and I add the substitute when I remember to do it, which is rarely, and it does fine. The Inliners board seems to think the substitutes really aren't neccessary.

 

I have heard it both ways, that the additive is neccessary. I never used it in my 54, and I beat the hell out of it and now its dead.rings and valves. but it has never been rebuilt and was a little tired in the first place. It probably isnt that expensive to have the valve seats done though... -J.

 

I've got unleaded valve seats in my 235" now, but I drove it for years without any substantial seat recession. I honestly don't think it's neccessary, but if you're rebuilding the head anyway, why not do it? It can't hurt.

 

I recently had my '51 216 done(basically the same). Ran a little over 400 bucks in Chi-town area. New valves,hardened seats,springs,surfaced and assembled,ready to bolt on.Valves weren't recessed too bad though,just rebuilding the engine so went ahead and did it.My '50 is still runnin a stock head,I just add a few ounces of Marvel Mystery Oil to each tank of gas.