I recently bought a 1972 Swinger with a 318 in it. I have read a lot of conflicting info from many sources on whether or not I can run pump gas in it or need to use a lead additive. I believe it has been run on pump gas for quite a while, but I don't want to hurt the valve seats any more than they have been if the 318 was intended for leaded in '72. Thanks for your help.

 

I don't know if your '72 has been reseated, but I do know my '70 was not, and here is the aftermath.

[IMG]local://upfiles/16801/EF62A2E6D98B44F382974CE34C672E83.jpg[/IMG]

[IMG]local://upfiles/16801/BBD88E69DA3F4604AF9CF8640EBF58EB.jpg[/IMG]

[IMG]local://upfiles/16801/93C0F13C171C4D5485167F9992E084DE.jpg[/IMG]

 

Check the junkyards for 75' and up 318 heads, these will have hardened seats. your early heads will burn valves without the lead additive in the fuel. Just like the pics Mr340 showed ya.

 

WOW!!! good thing ima rebuild my motor and re-do the heads soon!! I wouldn't like that to happen to my swinger at all sorry that happened to ya mr 340

 

You are best to switch the valves out if you're "in there" anyway. I've been fortunate. Have severalmachines all w/ original valves and never had a problem and I don't use lead additive either. But if I did rebuild one of mine I probably would change them just as insurance.

 

My heads can be saved, Machinist is going to install all new seats and replace whichever valves are bad. If you don't drive too hard you might not ever get to this point, but this 340 has already been punched.030, and has had 2 hard lives. I don't know why the heads were not done on the last rebuild , it was before I bought the car. When this happened, there was not much difference in performance, it blew a muffler off, and the idle was a little rougher than normal, but I was not expecting to find that inside...