Reply to "your advices (finally) - 351C engine"

quote:

Originally posted by PanteraDoug:
They look like triple springs with chrome molly retainers. I see guide plates for the push rods which means they need to be hardened push rods. Of course there are roller bearing aluminum rocker arms. It would appear the pedestals have been cut for screw in rocker arm studs. That's what you know.

You do not know the size of the valves, the condition and type of valve guides, the condition and type of valve stem seals. You do not know what was done as far as the valve seats and the port entry. Those you all need to know specifically. You would only need to remove one head, then disassemble one intake valve and one exhaust valve to see what was done.

4v Cleveland heads typically only need a good three angle valve job to show flow numbers around 300 cfm at .600" lift. The exhausts need some port work on the exit because of the bad angle.

You need to know how much lift the springs you have will allow before coil bind, and how much pressure they provide closed and at full lift.

If you have that equipment to disassemble then you can certainly do it in your own "shop". It isn't difficult.

You are going to get different opinions on what the port shape should look like under the valves. Stock, the head had in essence a restrictor ring cast into it. What that did was reduce the size of the port immediately under the valve and increase the velocity of the intake charge, thereby increasing throttle "feel" at low engine rpm.

Ford's "Off Highway Modification" booklet for the Boss 302, showed a cross section diagram of the ports with the suggested modification to the port for racing. Some don't like it and say that Ford racing didn't know what they were talking about.

They, Ford, are a lot smarter than I am and certainly that information comes from their racing experience. I've attached a scan of it here.

It wouldn't be a bad idea either to cc the combustion chambers, the intake and exhaust ports so you know exactly what you are dealing with. One of the things you need to do to "blue print" the heads is to attempt to equalize these so that the engine produces as closely as it can, the same amount of power per cylinder.