freeze plugs 318 same as Poly 318?

[kokxville]

I need a set for the Poly 318.I can buy them in the shop over here,but they can not tell me if they fit the 318 Poly.
Are these different,of are they all the same for small block mopars.

Thanks.

John

[hemigeno]

Do you have the freeze plugs removed?  There are two styles of freeze plugs used on engines from that era.  You can tell what style you need by feeling the lip of the freeze plug opening.  If it's smooth all the way through the opening's "bore", you can just measure the opening and get any generic auto-parts-store freeze plug that particular size.  No big deal.

However - if there is a "lip" in the opening about 2/3rds of the way into the bore, it takes a different/older style of freeze plug.  This is the type that looks like a small MoonEyes hubcap... like a slightly dished large coin.  Those are installed by seating them against the lip with the dished side sticking "out", and smacking them hard in the center with a hammer - thereby expanding the diameter of the freeze plug.  There are two ridges that follow the circumference of the freeze plug's edge that will dig into the block as the plug expands, and that is what holds the freeze plug in place.  

If you have that style, you need to make triple-sure that the older freeze plugs are fully expanded and well-seated.  When those suckers blow out as you're travelling down the road, you'll be walking the rest of the way.  Makes a great big cloud of steam too, when all the coolant leaves your block in the space of a few hundred feet.  DAMHIK.    I now keep an extra supply of the two sizes used on my truck's engine in the toolbox that stays in its storage box, as well as a ball-peen hammer to install them.  

You can convert an old block to the newer style by removing that ridge, but that's something a machine shop would have to do.

[tatrick2me]

All you need to do is take your old ones to the parts store and have them matched. Or go here http://www.manciniracing.com and contact these guys. For 50 years all they have done is mopar.