Magnum Heads

I have one of those heads that have a cosmetic crack and was going to use it. It is cracked through tthe exhaust seat but holds pressure, but was talked out of it by my machinest. Cracks keep going. He told me that he once pined a magnum head and cut out the seat and pressed in a new one, it only lasted about a month. Also he told me to cut one of my cracked ones and see for myself how thin they are between the exhaust and intake valves.

Part of the problem I have with the rockers is I'm using a small base circle cam and I had the heads milled to 57cc's so the pushrods need to be shorter, about 7.375 inches long.

I am using a Hughes valve springs and there retainers fit the od as well as the id of the spring

The replacement heads are made with thicker decks, more material between the valves, fiow better than a magnum RT head, and are made with a high nickel content, all for $475 a pair bare.
I have $100 in pressure checking junkyard heads.