tapping oil galley plugs?

[BerniniCaCO3]

Hi--

I rebuilt my engine as part of a community college course just over a year ago.
Immediately after building it, two of the three oil galley plugs that circle the camshaft, in the front of the engine, popped out, resulting in a loss of oil pressure past the camshaft (and lots of valve train clatter).

I pulled off the water pump and timing cover with the engine in the car, and tapped in two new plugs, this time, with jbweld [last summer] and it's held oil pressure ever since.

Now, I've pulled the engine to fix a couple other things anyway: header gasket that blew, oil pan that cracked (from that oil galley plug, actually), and putting in a better camshaft... and some other stuff.

I notice that my jbweld is now yellowed and brittle from the temperature and constant oil exposure.
I'm wondering if it's not a bad idea, to re-replace those galley plugs again, especially now that the engine is completely out and I can get to them-- and this time, thread the holes and install real plugs (like what's already in the back, and probably should always have been in the front).

Do you know what thread size they are?
Do you know if a tap will fit right in, or if it will require some pre-drilling?
Do you know how I might best remove the jbwelded tap-in plugs that are there?
OR do you advise, if they're holding pressure right now and haven't popped out in 8,000 miles, to just leave them the fuck alone?


thanks for the advice!
-Bernard

[86VickyLX]

Not sure of size, but I can almost guarantee it's NPT.

[BerniniCaCO3]

yeah, I believe--I know-- you're right about that. NPT is funny, right? They look like they're 3/8-1/2 outside diameter, tapered slightly of course (I last glanced at them for 5 seconds 12 hours ago, so forgive my imprecision), which means it might be 1/4" NPT or something?

[BerniniCaCO3]

at least in the back, anyway. The front is whatever I cut it to be-- but if an NPT tap goes right in, no drilling/modding/mess, then that's what I'll use.
Why are pipe threads tapered btw? Does it hold pressure better? I know it bottoms itself out, but I'm not sure why that's an advantage in plumbing.

[86VickyLX]

at least in the back, anyway. The front is whatever I cut it to be-- but if an NPT tap goes right in, no drilling/modding/mess, then that's what I'll use.
Why are pipe threads tapered btw? Does it hold pressure better? I know it bottoms itself out, but I'm not sure why that's an advantage in plumbing.

Forced fit, less likely to leak. Teflon tape is just a suggestion. lol

[sly]

teflon tape is there to lubricate the surfaces to make the fitting easier. it doesn't seal crap.

[gadget73]

The taper of the pipe thread is the seal. It jams the threads together to form the seal. Seems primitive, but it works quite well. And yes, teflon tape and pipe dope are merely lubricants so you can get the threads spun in further for a seal. I would not use either in an oil passage since its bound to shed a piece into the oil system and the less nonsense you get in the motor, the better you are. Oil is a pretty good lubricant, and mixes just fine with oil.

Honestly, unless the engine was in pieces I would not do this. You're going to get metal chips in the oil passages and they will go to places that they will not do favors for. The only way I'd consider this is if the block was stripped bare and about to go into the cleaning tank to make sure nothing got fed to my bearings. Lots and lots of high mileage Ford smallblocks out there with the cup plugs that haven't blown them out.