I was cleaning up my dad's garage ( I'm 19 and live at home) a little as I plan to pull the tranny in the Malibu and install a Transgo shift kit, so I need space and clean surfaces to work.

Anyway, we have a 305 block that came with my Malibu, it is an 89 OEM Roller block. Anyway, I studied the deck surfase for a while so I could know what wasn't a 400SB deck.

I found a tapped and plugged hole near the back of the block (not the oil temp sending unit tapped hole, a different one), it is near the rear intake manifold rail, but on the same slope as the head/deck surface. I took out the plug and shined a light down and saw what looked like the cam or some kind of shiny, smooth surface. The plug that I took out has a 1/4" square "drive", I just stuck the 1/4" breaker bar to loosen it up.

Then I found another similar plug, except with a hex pattern for an Allen wrench, above the oil filter area. I shined a light in that one too but all I saw was the are above the filter.

I replaced both of the plugs, even though I doubt this block will ever get re-used.

Anyway, what the heck are these holes drilled and tapped for, and what sort of things can be hooked up into them? Gauges, coolers? Dry-sump?

Thanks.

It a passage used to drill an oil galley during manufacture. I've never bothered to trace where it comes/goes.

But you better be SURE that the plugs are in place before running the engine, as well as the one on the bottom near the rear main. Otherwise, no oil pressure and oil spraying every where! Don't ask how I know this.

Never used a Trans-go Kit, only B&M, but I don't think you need to drop the trans to install it. Unless you have other mods in mind also.

My 406 motor had a real thick, solid metal plug there b/c I tried drilling it out and gave up at a 1/4" deep...

pdq67

I know that I could do it with the trans in the car, but its waaaaay more comfortable doing it on an engine stand while standing over the tranny rather than being under a 4000lbs car for God knows how long, tranny fluid dripping on my face and fussing and cussing while working in the cramped space. LOL.

If I had a lift like on HPTV, I wouldn't even think of taking the trans out. But I'd rather spend the least amount of time under the car, even with jack stand and wheel chucks.

So, are there any uses for those holes I found?

Originally posted by pdq67:
My 406 motor had a real thick, solid metal plug there b/c I tried drilling it out and gave up at a 1/4" deep...

pdq67 =

Just drill it, tap it & use a slide hammer,
comes right out ;)

When you do a Shift Kit, all that gets removed and worked on is the valve body.

Yeah, but that involves pulling the pan off, which usually results in being bathed in ATF. Not all that fun, done that already.

Anyway, I'd like to have it out to have my cousin (professional auto mechanic) look it over for any serious damage.

Originally posted by Slowpoke70:
So, are there any uses for those holes I found? The one on the deck is half covered by the head & is just there so they could drill the oil passages as was stated.
You could use the other one for oil pressure or temp if you wanted but it is also there so the oil passages could be drilled.
I use it for a temp sensor on the dyno.

Cool, that's the info I was looking for.

Thanks Mike.