Big Block Cylinder head Core Plugs

Pete · Post by **Pete** » Tue Mar 24, 15 7:07 pm

Anyone know off hand what size the core plugs are on a 440?

I note that the core plug sets only include the Block and not the heads so any information would be appreciated, thanks.

Pete

shovelheadrob · Post by **shovelheadrob** » Tue Mar 24, 15 7:29 pm

Pete, I'm pretty sure that they are 1" in the ends & 1.25" on the exhaust face. They are probably around 0.010-0.020 bigger for interference fit.

Pete · Post by **Pete** » Tue Mar 24, 15 7:37 pm

Thanks Rob.

I decided not to be lazy and pressure tested the Block and heads, and waddyknow - a Core plug had rusted through!!!

Just as well I checked, been burned before...............

shovelheadrob · Post by **shovelheadrob** » Tue Mar 24, 15 7:43 pm

It's one of the things I have always changed on a rebuild, I also coat the back of them with a good grade of silicone, just enough to give a thin film of cover, it gives them a bit of added protection although most antifreeze should have corrosion inhibitors in it. Problem usually occurs with engines that have been drained for the winter, moisture & air can reek havoc.

Pete · Post by **Pete** » Tue Mar 24, 15 7:46 pm

All good points, Rob..