Known use for 5011 block bolt hole

[ozzie7]

Sorry if my nomenclature is wrong.
But I was wondering if anyone can tell me what the casting hole (see green arrow) is for on a 348.
It is not a threaded bolt/stud hole on the three 348 blocks I have.
I have seen that bolt hole in use on a 409 but wondered if I cut a quarter inch off the top if it would matter for anything.
Wanted to put the breather shown in the second pic on it but it doesn't quite clear as seen in 3rd pic.
Need to shave about a quarter inch off the top.
I know I should probably just get a different breather rather than hack up the FJ block.
But this one is nice... unscrews and has a cleanable filter.... and I bought 2... (I'm trying to stroke my ego and justify my purchase now).
One for this motor and one for the tri-power motor (which has the same clearance issue).
Heck...it might not even have clearance for the firewall.
Maybe someone has a suggestion of one like it that's smaller in diameter that fits the 348?

 

[Jim Sullivan]

The hole should be an oil passage with a pressed in plug to seal it. Maybe have the breather machined for clearance if there is enough meat to it? I wouldn't go grinding on the block. jmo

 

[Phil Reed]

I think it's a fixture locating hole. I have a 60 dated 623 block and it has these same holes in the front and rear.

 

[Jim Sullivan]

I think it's a fixture locating hole. I have a 60 dated 623 block and it has these same holes in the front and rear.

I continue to learn something new all the time on this great site, thanks for the correction Phil.

 

[63 dream'n]

What about this show cars PCV kit it's kind of hidden........
......they have 1 for 2x4 manifold and a single carb.

 

[cuzineddy]

That is the vent hole for the road draft tube.

 

[threeimpalas]

Use a PCV setup or road draft tube. You need to pull a vacuum from that location, which only using a valve cover breather mounted back there will not do.

 

[ozzie7]

Thanks for the replies gentlemen.

I like the idea of converting to a PCV setup.... not sure if I have enough vacuum ports on the Carter 3012.

I didn't realize the road draft tube created a vacuum... I guess as you gain speed, the wind rushing past the opening creates a "draft" effect.
The draft tube method is probably the practical way to go.

I got the breather idea from a post I came across at the chevytalk forum by a member named Jens.... not sure if Jens is on this board.
Here's the pic that was posted there.... I found the breather at speedwaymotors.
I spose I'll be calling them to get an RA number since it will probably hit the firewall anyway.

 

[threeimpalas]

That's exactly how the road draft tube works. As you're driving, the airflow under the car pulls a vacuum on the draft tube, which in turn ventilates the crankcase. Unfortunately, it can also coat the underside of the car with oil droplets. Not something you want on a show car.

If you've got other items that need to pull a vacuum and have run out of ports on the carburetor or intake, you can T the line.

 

[jdk971]

remember the black lines down the highway. jim

 

[ozzie7]

Nowadays you see a black area in the center of the lane on the freeways right after a bump or dip in the road.
All those clinging drops of oil getting ready to drop finally get the extra help from the jolt/gravity.