Question is about the three oil plugs, 2 in the front, one in the back on my 66 442 400ci engine.

Based on what the machine shop said (and the rebuild book (sa502 Cartech Inc), their is one plug with the hole in the center that goes on the right side of the engine (passenger side) to lubricate the timing chain, the left side is the same plug without the hole, and the plug in the rear of the block (inside the engine behind the freeze plug) is just a plug.
Just want to verify this before I start the build process.

Tom

 

I would pull any removable galley plugs in an engine rebuild regardless, just remember what goes where.

 

The plug "inside the engine" is in the hole where the distributor goes, it must have a hole to oil the distributor and cam gears.

 

Make sure your machinist does not loose this one.
And make sure it is reinstalled.

 

That part is definitely not true. Like Sugar Bear said that one has a hole in it to oil the distributor gear.

The two in the front with the hex heads are different sizes and can only go in one way.

 

Two in front have different threads, yes one with oil hole. In rear there is one behind a small core plug and yes it has a hole for dist gear oiling.

 

The hole in the plug by the distributor should be 0.040" diameter.

 

Thanks for all of you responses…….now the problem is where to get one of those rear plugs withe hole in it.

The machine shop doesn’t have it and said the plug was already out, which is entirely possible as the block was completely torn down/stripped when I bought the car.

I’ll call some other machine shops to see if they have one, but if anyone has a place to source this plug, let me know.

Tom

 

Tom,
That one is easy. Its just a 3/8 pipe plug with a .040" hole drilled in the middle. Your machine shop should have plenty of 3/8 pipe plugs. Then all you need is a teensy .040 drill bit. I dont think I have ever see the predrilled plug anywhere but I really have not looked very much.

 

Mondello use to sell them, when they were in business. I bought some from them. Maybe some still has some, and may be for sale on Ebay? Maybe some of the Olds vendors on this site sell them?

 

Just looked on Ebay, there is two for sale right now.

 

Link ?? I just did a quick search and didnt see any. If they are asking for anything more than a couple of dollars they have lost their minds

 

Bill, that what I’m finding out…..no one sells them.
i did find a local machine shop who would drill the hole in the right size plug…….that was going to be my next question which you answered ​​.
I will give him the info and get it done.
Thanks for the help! Much appreciate!

Tom

 

Never mind I found the one on E-bay. $16 !!!!! They have lost their minds.

 

Tom,
If you cant get it done local let me know and I will drill one and stick it in the mail for you.

 

Appreciate the offer….will call you if I can’t get it done.

Tom

 

Curious, are they NPT pipe plugs, or a pressed in metal plug?

 

3/8 NPT The OEM GM number is 404199 but they have been discontinued for quite some time.

 

Something like this work? 3/8 npt.

Drilled oil galley plugs

 

3/8 - 18

 

Yes, 3/8 npt. is 3/8-18

 

Yup. That is all they are as long as the hole is about .040" The plugs cost about 30 cents each and drill bits are less than a dollar Thats why the guy that has them for $16 on E-bay has lost his mind

 

Got the plug from a local machine shop who was well versed on that engine. Drilled to .040.

Thanks to everyone for your input!

Tom

 

Nice! That plug is mission critical, no plug equals a big oil pressure loss, a plug without a hole equals gear failure and the correct plug equals miles with smiles in your Oldsmobile.