will the 70' 350 heads take the abuse that the gas of today will give it? beings that they were for leaded gas and today we have unleaded, will they need hardened seats????now i need to know for sure, no guesses here, i will be running the highest octane (which is like 92, or 93) I know you can get the racing gas (104) but that stuff is too expensive to run all the time
The 70 heads will run just fine..... they have a high nickle content....hardened seats are really not necessary on these. I run different octanes depending where I am going. If driving a ways I will run 91 unleaded. If I am am cruising around town (looking for Fords) I usually run 50/50 mix of 110 and 91 unleaded. Mike
I do remember reading about nickle plated exuast valves starting in 1975 for use with unleaded fuel, I think it was in new car brochures for '75. I dont think Buick did anything as far as the heads are concerned. You can run stock size stainless exahaust valves to be on the safe side. Mark
I have never had a problem with valve seats on my 350s and have always ran unleaded. I believe that RPMs and high spring pressures can contribute to the problem. If your valve springs are mild you should be fine...
thanks mike, I think you may have told me this before, i wasn't quite sure tho, i have 76, 350 heads that i was gonna use just to be on the safe side but i did find out that the 76' have two water jakets that the 70' don't ( on the top twards the intake, on the cumbustion chamber side between cylinders 4,6 and 3,5, basically the middle of the head, 76' has two water jacket holes)
I run 93 unleaded in my 70 GS 350. The compression is 10.25:1 and I've never had a problem. I will put some lead additive in it every once in awhile though.
Nickel plated exhaust valves became standard in '71 to allow for unleaded fuel. Nothing was done to the heads, however, due to their high nickel content.
