What is supposed to go in this hole?

[billd]

I'm just about ready to put this engine in the car. The case is from a 76 Carerra 3.0. The top of the crankcase just to the left of the breather has a hole (left of center in the attached picture). On a 2.7 I recently rebuilt there was a third stud in this position. What is supposed to go here on the Carerra 3.0? I suspect that if I don't plug this hole, oil is going to come spraying out. Any advice you may have would be greatly appreciated.



----Bill

[Walt Fricke]

Aren't those the three holes through which the studs (and aluminum spacers) go to hold the CIS throttle bell crank? I suppose you are running carbs, and don't need this bell crank?

I think these are blind holes (don't penetrate into the crank case innards), but you ought to be able to check that easily enough. Or just put some goop on any old M8x1.25 bolt and use it as a plug.

What's with the small Phillips screw and stuff below one of the holes?

Walt

[Porschekid962]

Walt is right. That hole takes a stud to mount a throttle plate. If you dont need it then plug it up with a shorter bolt or something along those lines.

[billd]

If these held a third stud - like on my 2.7 - then someone drilled out the threads. The hole is now about 15mm in diameter and it is partly open at the bottom. Perhaps I can drill and tap it (without getting shavings into the case) for 3/8 NPT and put a pipe plug in it.

[billd]

If these held a third stud - like on my 2.7 - then someone drilled out the threads. The hole is now about 15mm in diameter, has no threads, and it is partly open at the bottom. Perhaps I can drill and tap it (without getting shavings into the case) for 3/8 NPT and put a pipe plug in it.

[Walt Fricke]

Good news for you.

I just did something clever (which I should have done before posting the first time): went and looked at the Carrera 3.0 case I have in my garage awaiting assembly into a SS 2.8. Guess what: the boss the stud goes into sticks out laterally from the rest of the casting, so the hole does not go into the case, it just goes through a sort of fin outside the case. You can just ignore it.

To prove this to yourself, stick an air gun into the hole and blow and see if you get air out the breather. Or pressurize through the breather and see if any comes out the hole. From the picture it doesn't look like the boss was drilled entirely through, so the drill did not pass through the intervening air space and into the case.

Bizarre. Botched attempt to remove stud? Bottom line: ignore it.

I do like to close any unused holes in the fiberglass shroud, though. Probably doesn't matter, but the more air to cool the heads and cylinders the better. Silver tape underneath, and silver tape on top (sticking together where the hole is) will be strong enough for this if you want to pull the cover but don't want to fiberglass the holes shut.

Walt

[billd]

I think the hole is through to the inside of the case, but I'll test with compressed air when I get home to make sure.

[billd]

Sure enough, this does not go through to the case. I shot compressed air into this hole and its coming out somewhere - perhaps behind the flywheel - but is not coming out the breather.

[Green 912]

you can fill it with JB weld just in case.

[A930Rocket]

As suggested, I think it also should have a stud there. If you try to JB weld it up, you'll need to make sure you don't drip it into the engine. Even 5 minute JB weld will drip. Maybe you can use a piece of solid round aluminum to fit it and then JB weld it in, possibly tapping it for the stud first?

If it's on a stand, you can invert the engine and then install it to prevent the JB weld from going onto the engine.

[Keith Perry]

Did air escape there when you pressurized through the breather?