ok i filled my rad up with fluid and i started leaking fluid out of a hole between 1 and 3 spark plug hole
its a late 70 model 350
the hole is rite by the header somewhat
i think its where i plug my therm meter up to
but what do i put in there to keep it from coming out?
i was told it was a freeze plug but idk
thanks

 

It should just be a pipe plug. Its either 3/8" or 1/2" NPT.

What did you take out? If you took something out, thats why its leaking.

 

It will be 3/8 NPT, like stated above. Really common, easy to find size. Just put a plug in it, be sure to use thread sealer or teflon tape.

 

I'm not too sure about plugging it up because that's where my temp sender is installed.
I have a hole like that on both heads.
The other is plugged but should hold my temperature switch. I could not get the plug out...snapped a brand new alan wrench socket trying...much to the displeasure of my friend who lent me the tool to remove it...lol.

However, Your setup may be different and have the sender somewhere else??
Though you say that's where you hook up your therm meter??
So what did you remove in order to hook up your meter in the first place??

 

Until mid '80's most heads were 1/2"NPT

 

Your sender for the coolant guage is supposed to be in that hole.

 

no i didnt take it out.
it was already out
was filling up with coolant to fire up the engine than see it

 

is there a specific kind of plug i need to use it for my coolant gauge

 

You'd need a coolant temperature sender, not a plug. If the hole in the head is bigger than the sender, use a pipe bushing.