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Valve job!?!

I have a 78 f100 with a 351, it was sucking through the exhaust and coolant was disappearing, so I pulled the head today. Clean them up and water tested the intake and exhaust on both heads. Why does each head have one exhaust chamber that would allow the water to flow from the exhaust out the intake chambers but on the same cylinder if I poured it in the intake chamber it would stay. Also, should I get the valve guide replaced if water from the chamber drip through it?
 
I have a 78 f100 with a 351, it was sucking through the exhaust and coolant was disappearing, so I pulled the head today. Clean them up and water tested the intake and exhaust on both heads. Why does each head have one exhaust chamber that would allow the water to flow from the exhaust out the intake chambers but on the same cylinder if I poured it in the intake chamber it would stay. Also, should I get the valve guide replaced if water from the chamber drip through it?

That dont sound right,that is what I beleive to be a cracked head,
an may not be repairable.
 

DNFXDLI

The Token Canadian
Staff member
There should be nothing like that....what CB said, possible cracked head.
My understanding is that there were casting issues on some of the 351M heads that resulted in what you are describing.
 

DNFXDLI

The Token Canadian
Staff member
Damn, don't say it. I just don't understand how it goes through one way but doesn't the other?!?!

Wait...maybe I misread your initial post..it's only flowing one way?

I went back and read your post...hmmm.
 

DNFXDLI

The Token Canadian
Staff member
I still don't understand how it does it?

Nor do I.....so if the head is upside down and your pour water into the CC, what happens to that particular pair of valves/chambers?
 
I lay the head on the intake side and pour water into the exhaust chamber it doesn't flow out the valves it flow out the intake chamber, but if I lay it on the exhaust side and pour it into the intake chamber it just fills it up and will not leak out.
 
I have another one for you...I know I have 351C heads but the spark plugs I pulled out were 5/8 spark plugs. The C usually came with 14mm.
 

DNFXDLI

The Token Canadian
Staff member
It should not flow into the intake port....it's been a long day and I'm trying to think if I'm missing the obvious....but with the head off and the springs closing the valves, there should not be any interaction between the ports.

It's not the crossover passage is it?
 

DNFXDLI

The Token Canadian
Staff member
I wondered.....I still have a few brain cells left!
 

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