Vacuum Connections (292 w/ Holley 4 bbl)

[mattdmeyer]

I'm getting my project back together, but I had a few questions on the vacuum connections. I upgraded the stock manifold and monojet carb to an Offy with a Holley 4 bbl carb.

So far, we have the following connected:
The fuel line from the fuel pump to the fuel inlet on the carb.
The vacuum line from the HEI to the little port sticking out the side of the carb. I'll have to get a picture of it tomorrow to better illustrate this.
PVC valve going from the top of the value cover to the intake manifold.
Power brake vacuum line from the power brake booster to the manifold.

The one I'm scratching my head on is the second line on the top of the valve cover. That used to go back into the air filter box when using the 1 bbl rochester. But now that I'm using the Holley can I just plug that up?

Am I missing any other vacuum connection?

Thanks!!

[Gmc.guy]

The pvc sucks out and that hole lets it breath in. They used to draw through a little filter in the air cleaner. A pop in breather usually gets used. If you block it the pvc will not function properly. There is lots of styles with a grommet that you could pick from to suit the look of your engine Sounds cool by the way!

[mattdmeyer]

Thanks Gmc.guy.

How would things change if I didn't use a traditional air filter, but went for a cold air intake instead? I have very limited height clearance in my engine compartment, so I'm going to probably have to go with something like this:
http://www.spectreperformance.com/se....aspx?prod=751
Would I need to tap into the duct so the second valve cover connection could get connected directly to the air cleaner.

One thing I noticed is that chevy_mike doesn't have that second hole in his valve cover. Is the inlet coming from somewhere else?
http://67-72chevytrucks.com/vboard/s...d.php?t=684440

[Gmc.guy]

There is lots of ways to do it. Most breathers have a filter but some are just baffled. Filtered air should be drawn in.

I think a few of the inline valve covers had the hole on the side near the back. I had one that was an oil cap too with the twist/lock tabs You might be able to nipple the cold air intake and put a hose similar to a factory setup so you have filtered air. There is lots of options. I have seen people use the little k+n type pocket bike air filters too for a custom look Here is a good place to find sweet ideas. There is a thread all about 6's here I check out once in awhile. You can prob get some nice ideas there, you might burn 4 or 5 hours checking them out like I did haha.

[Gmc.guy]

I just checked out Chevy Mike engine you linked. It has a breather and hole. It's the chrome cap beside the pvc. That's what I meant by breather, sorry

[mattdmeyer]

That actually helps explain a lot. I thought that was a fancy oil cap. Now I know what to look for.


Off topic: I may need to upgrade my valve cover to something like this. It's so much fancier than the original GM one.