346 core plug sizes and locations

[gary griffin]

346 has how many core plugs/freeze plugs?? Where are they all found? Is there a diagram or picture of that?

Apparently my rebuilder did not remove any of them and there was  a pin hole leak one of them in the crossover.  I figured they were new and just defective but found out today that they were old and rotten. Now I have the challenge of geting the water jacket drained and flushed and new core plugs installed. I do not want to miss one.

I was presented a list from my previous question but the information is vague (Or my mind is?) and covers several years and variables. My car is a 42 but according to records it got a 41 engine in it's first 8 years. It was owned by the military and sold at a surplus auction in 1951.

Thanks in advance all help is appreciated.

[Steve Passmore]

I cant believe your re-builder didn't remove them Gary, that should be a fundamental procedure.  How else could he be sure all the swarf was cleaned out after each machining? unless he only did the machining and someone else assembled it?
Of all the 8 flathead's I've dismantled I have never had one that didn't have the rear 2 or 4 cylinder completely blocked with crud in the water jacket. Sometimes it has to be chiseled out!

If the six plugs on the sides of the block have not been removed I suggest you get them out and see if theres any build up of muck in the rear sections, if there is its a helluva job getting it out without removing the heads and prodding down the water holes.   Mostly pressure washing down these holes is the only way.  Hope you find it clean in there.

As to the number of plugs, apart from the six on the sides and the crossover two there's only one other but thats covering the end of the camshaft and is not a water jacket plug.

[gary griffin]

Thanks Steve,

   Yes I am very disappointed in the machinist who did my rebuild, first I was angry at his constant delays and now  I am faced with the challenge of cleaning out the water jacket and putting in new plugs.

   does anybody know the sizes of the block Plugs?

[Bill Ingler #7799]

Hi Gary; Here is the expansion plug chart from the Master Chassis book and it shows 1 & 3/4 but I have known the book to be wrong. I would check with NAPA or call Terrill Machine to verify the size.   Bill

[gary griffin]

Thanks again everyone. We pulled a soft  plug on the rear of the drivers side and it was pretty clean  and it looks like  the machinest  did not notice the pair of plugs directly under the carburetor.
Out of the woods for now I think. Start up this afternoon but I am unable to view it but I will try to post some video of the car in it's current condition and with the engine running in a couple of days.

Thursday is my normal day to visit the shop with donuts for the crew and any parts or information they need, but doctor appointment is interfering.  Well Friday or Monday will be it this week.