Need more vacuum ports

Don Jacks

Well Seasoned Member
Supporting Member 3
Using one runner as a source for things is not a problem.The factory used the number 8 cylinder intake runner as a source for vacuum modulator,and vacuum advance for many years.The hole in the middle has more to do with volume and balance between banks of the engine than anything else.
 

pvs409

Well Known Member
Supporting Member 11
check these connections on my 62 Impala SS 327 convertible with a 700 R4 overdrive transmisson-everything worked great...
  1. Vaccum for 700R4 to hollow carb stud drivers side rear of carb
  2. PVC to replace the factory road draft off the back of the block to the back of carb
  3. Power brake hose from drivers side off the back of carb
  4. Vacuum advance small hose for distributor off the passenger side of the T
  5. # 2, & # 4 are the factory style connection locations 63 and up to my knowledge
  6. factory power brakes in 61 to 64 where this way on 327's and 283's
Paul
P1010872.jpgP1010875.jpg
 

427John

Well Known Member
Looking at the carb base, I can see that the tapped hole in the middle carb is ‘fed’ by both sides of the carb, which I assume provides a constant vacuum? So if I tapped the manifold, but only into one side , would that be an issue? Does that make more sense?
Yes neil if you look at my earlier post about feeding from the center,I tried to specify for high capacity loads such as power brake boosters,I didn't mean to imply that would be necessary for small capacity loads such as modulators and vacuum advance.
 

Gofish

Well Known Member
Those hollow carb mounting studs look pretty simple, but might not have the look you’re after.

I’m not finished yet, but per my posts above I’m running 5/16 steel line for my PCV and brake booster lines, and then tapping 3/16 nipples into the 5/16 line for other small needs into the brake vacuum line. I tested this out with some plumbing solder and it works really well, but I’m going to use solder for gutters, etc. for the final. Here are a few pictures. It would be more work for you, but it would be hard to even notice the vacuum gauge line (I’m putting the nipples behind the head) and would get rid of some rubber hose.

80B03D18-0EE4-4F87-9980-564272ECBA94.jpeg8F330937-502B-465B-9025-93E247B3CE61.jpeg5C21DCFC-9F03-4CA3-B738-A25A45641104.jpeg
 

Gofish

Well Known Member
Here’s a photo of the distributor advance and trans lockup lines supplied off the hard line to the brake booster. You can also see the hard line coming from the PCV. Ignore the scattered wires, fuel line, and throttle linkage - it’ll be cleaned up after the body goes back on.


C6F54838-F1D8-4CFD-B2A6-CDEA010816C1.jpeg
 

38Chevy

Well Known Member
I always try to hook the pcv valve to the primary Carb base. In the case of 3-2's the center carb base, 2-4's the rear carb base. Thats so blowby will be evenly distibuted to each cylinder to be burned. Anything else like power brakes, dist advance, trans modulator can be run off of any location and stacked if necessary.
 
Top