Re: Wanted plug for 396 427 four bolt main motor
 

It is kind of interesting. At one time I assumed the "W" referenced a magnetic plug since the 3/4 plugs on the muncies and later 67 and up 12 bolts were cast with the W also and they were magnetic as well as the 1" ones used on the 65/66 12 bolts but these I have are non magnetic bought for a 66 -L72 and are actually date coded also on the inside.One is march of 68 and the other Feb of 69.Strange why Gm would put that much detail into a plug?? https://www.yenko.net/ubbthreads/imag...lins/dunno.gif

Re: Wanted plug for 396 427 four bolt main motor
 

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Rooting through the toolbox junk drawer for something else I came up on one of these the other day too..
It's similar to the lower pic of Joe's w/ a diamond shape on the head but in a deeper recessed circle..
I looked to this thread to compare but didn't repond when seeing Barry had noted he wanted a 'correct' one and the head on his pic shown is smooth also taller in the square part of the plug than this one has..

Aside from the diamond/circle part, this one's a 1" plug and looking into the bottom it's recessed smoothly and looks kinda' like the inside of a trim tag rivet..
It's about 1-1/16" total height, the thread part is about 5/8" high and the square part above the threads about 7/16" high...the square itself is 5/8"..

Happy to pop it in the mail to Barry if it's suitable...or if it's no good to him, someone else can have it after he responds?.

Thinking further, are waterpump bypass plugs the same size and an outie head too?.

~ Pete
https://www.yenko.net/ubbthreads/imag...lins/beers.gif

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See if it is magnetic Andy. I have seen the 1" ones with the circle in 65/66 12 bolts less posi since this style does not have the flange for the tag. Just wondering.

Re: Wanted plug for 396 427 four bolt main motor
 

Maybe the "W" is actually an "M" (for magnetic) and you are standing upside down at the moment. https://www.yenko.net/ubbthreads/imag...mlins/grin.gif

Re: Wanted plug for 396 427 four bolt main motor
 

I checked all of our plugs this morning and they all have L78 stamped on them.... https://www.yenko.net/ubbthreads/imag...mlins/wink.gif

Re: Wanted plug for 396 427 four bolt main motor
 

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Maybe the "W" is actually an "M" (for magnetic) and you are standing upside down at the moment. https://www.yenko.net/ubbthreads/imag...mlins/grin.gif

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That may be Steve it was there for some reason.Tom it would take you 2 years to check all of your plugs in that Nova fleet. https://www.yenko.net/ubbthreads/imag...mlins/grin.gif

Re: Wanted plug for 396 427 four bolt main motor
 

The one here doesn't seem to be magnetic itself...a magnet does stick to it though..

No markings inside either...just what looks like the chalky remains of coolant inside and what made me think of the waterpump bypass plugs..

I used to swap the bypass plugs for a fitting to hose into the truck style 4-core rads I'd pull out of Caddy deathmobiles at the boneyard...most guys seemed to prefer to stay away from parts off these!.

~ Pete
https://www.yenko.net/ubbthreads/imag...mlins/grin.gif

Re: Wanted plug for 396 427 four bolt main motor
 

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I checked all of our plugs this morning and they all have L78 stamped on them.... https://www.yenko.net/ubbthreads/imag...mlins/wink.gif

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You need to find one that has NOS stamped on it. https://www.yenko.net/ubbthreads/imag...lins/smile.gif