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Does anyone know the size or have a Napa/Kragen/Autozone part number for the core (freeze plugs) on a 327? Preferrably brass ones.

I am going to pull them out before I paint so I can scrape out any accumulated rust from inside the engine.

Thanks,

Others may have different experiences, but I've not had good luck with brass core plugs. Though the situation may be different with the cup-type like your 327 has, I have many of the dish-type brass plugs begin to seep not too many months after installation. I've assumed this is because the brass begins to compress or relieve under the constant pressure of the fit, whereas steel holds its shape.

The trick with any and all freeze plugs is to coat the backside that contacts water with a nice thin coat of black RTV silicone. I've done this on every engine I've worked on that I had to remove the freeze plugs. This seals them up, and resists corrosion. Also, I use brass freeze plugs exclusively. I've never had a problem with them, ever.

Go to any Cadillac dealer and ask the nice man behind the parts counter for "cooling system treatment tablets" These are the miracle pill of the 80s still in use today.
They are really just ground ginger root, compressed into a horse pill. GM reluctantly began offering these in the early 80s after introducing their HT-4100 "wet sleeve" V-8, the predecessor of the Norstar and such. They were faced with catastrophic returns for coolant going everywhere it shouldn't, were trying all kinds of sealing compounds from Dow (which required complete disassembly to install) and were losing the battle when an experienced dyno mechanic, an old school wrench told the young engineers to "put some ginger root in it"--they laughed, kept on trying the next technological miracle, dealer reports kept multiplying. The mechanic went and got some ginger root, ground it up, put it in a test car (one of the many that were piling up daily) and VIOLA! the problem went away. The green engineers couldn't believe their eyes, tested the S__t out of that car and it held. The next week GM was the no.1 consumer of ginger root, cranking out horse pills to ship to the dealers. They put two in each engine, one per side at the Livonia engine plant.
I put one in each cooling bank of every engine I rebuild, and no problems. If you have a freeze plug leak after rebuilding it will stop (permanently) after about 15 minutes of running at temp.

I guarantee you it will be the best $6 you will ever spend.
One week after you start using the pills you can open the radiator and see no evidence of them ever having been there, no coating the rad core, robbing efficiency.


Check it out

I need to pick up two brass freeze plugs to block off the exhaust and preventing those gases from traveling thru the intake manifold. It takes a couple of minutes to warm up the engine, but after that no problem. I block them off so my nice bronze manifold doesn't turn black.

None of my plugs are leaking at the moment. But I just going to remove the current ones so I can get as much rust as possible out of the inside of the engine. I am also going to pull the water pump so I can clean out the distribution tube also.

Any ideas on the correct plug size to get?

In a V8, a error often made nowdays is to install the common 1&1/4" freeze plugs, when the correct size is
1&49/64". The extra .0156" does make a difference in the tightness of the fit.

Joe H

JoeH -

You wrote:

Quote:
However, I can't get the math to work with the numbers you specified. A 1-49/64" plug is 0.515625 larger than a 1-1/4" plug - making it a bit more than a tight fit.

Please clarify, as I don't wanna make a wrong guess as to what you meant.

Further to Mr. Pushbutton's comments on the ginger root tabs, you need not go to a Cadillac dealer. Any GM dealer and almost any decent part store can get them for you, they are AC/Delco Part # 10-108 for a packet of 5 tabs, enough for a 32 quart cooling system according to the instructions. Ingredients are ginger root, almond shell, sodium carbonate, and a glycol-derivative organic. They've worked well for me on the only occasion I used them.

Randy. I doubt that the brass will hold up to the exh heat. U Need STAINLESS steel. Also, if u block off the exh. passages u'll have a lot of trouble getting the engine to run right at temps below 50 degrees.

SO, if u keep the manifold from burning the paint then how will u keep the head ports that mate at the Exh manifold from burning the paint there??? I think u're dreaming the impossible dream.