72' OEM 350. Ordered new spark plugs from summit. Champion RC12YC.


I started pulling the old plugs, and they are Champion RJ18YC.


Besides, the different socket size between the both there is a notable depth difference. The RC12's looks like it will screw into the head about 3/8" deeper.


So I'm wondering if I got the wrong plugs and it I screw them in there they'll hit the pistons. Or was the wrong plugs in there in the first place.

 

RJ14YC is what Champion recommends for you car. I think that RC12YC is a conical seat plug. You need a gasket seat like the RJ

 

Try ordering them from Rock Auto and maybe you'll get plugs for an Olds engine instead of ones for a Chevy engine.