Re-using heads without rebuilding

[3514boltstang]

I have a set of closed chambered 351c heads that were not rebuilt ever,they are complete.can I bolt these on if they appear to be in good shape?i turned them upside down and filled the chambers with water,no leak down through ports so it looks like the valves are seated well.

 

[turtle5353]

That's asking for trouble. At minimum the valve seals should be swapped out. After sitting a long time they can become brittle and go throughout the motor and plug up the pickup tube and screen. Also the stock valves are pretty much junk. They are a two piece design and fail. I had one fail and destroy my last motor. For a few hundred bucks you can have them gone through and not have to worry about it.

 

[Canted 393]

+1 on what kevin said, plus canted valve heads almost always need valve guides.

 

[3514boltstang]

Damn,I was hoping to get away with maybe just replacing the seals,they want like 900.00 to rebuild heads around here.

 

[Don C]

You can't use water for checking valve sealing. Water is too "thick" and any carbon or oil will prevent it from flowing through a fair sized gap, unless you put it under pressure, even then it wouldn't be a good test medium.

You need something like brake or carburetor cleaner or lacquer thinner. Gasoline will work but not recommended due to flammability.

Other than that, I agree with what Kevin said. It's a lot of work to install a set of heads and then remove them if anything turns out wrong with them. A good machinist will also check for cracks.

Make sure the cylinders, rings and pistons are in good condition. Removing heads is a big percentage of an overhaul, now would be a good time to go through the engine.

 

[rvrtrash]

I agree with Don. If you're going to take the engine apart, just do it right the first time and then you don't have to come back and do more later. In the dark ages (1970's) I'd rebuild a set of heads and then find within a year I was back in the engine because the bottom end needed attention.

Steve