Oldguard 7

I wish to install a recently purchased mighty demon carb. The carb has one large port underneath the rear float bowl. The pic on the installation instructions say this port is for the PCV. My question is what set up you have to run a hose for the brake booster? I have thought of using a t-fitting from this port for both but not sure if I will have issues with both the PCV and the brake booster or one or the other If anyone is willing to post pics or their set up and suggestions it is greatly appreciated.

resdoggie

Think of it as a manifold vacuum source. It can be used for pcv, brake booster, vacuum advance, etc. but there are other vacuum ports for some of those items. Manifold vacuum is the same everywhere below the throttle plates. So if you "T" in another accessory, it will work. You could also drill and tap a hole in the intake manifold for an additional manifold vacuum source. On my setup, the pcv port is on the front and plugged as I don't use a pcv system. On the back of the carb is a larger port like yours which is used for the brake booster. There is also a port in the intake manifold just below the carb pad. I use this with a "T" for all other vacuum requirements.

Street Rat

I made a vacuum "tree" off the rear port. It's hidden under the distributor. I made the tree out of brass fittings that I found on Ebay and various sizes of vacuum hose. I have my power brake booster hooked up to one side of tee. Everything else is plumbed off of the other side of the tee. The PCV valve is hooked to large front vacuum port on the carburetor. I found this highly succesful.

Sorry I can't show a picture because the hoses and tees are basically hidden.

lars

As noted in the other posts, there are 2 ways to do it:

You can make a "T" line at the rear vacuum port on the carb. I like to make it short enough so that it's completely hidden under the rear bowl:


If you want 2 separate ports, you can simply drill and tap your intake for another nipple - this is clean and easy:


Lars

Oldguard 7

I did a tee set up yesterday but was unsure if it was ok to do. I found your how to set up a speed demon carb tech sheet after I posted this thread. It verified this was ok to do. Your reply seals the deal. Btw I did meet you during the TFB in NOVA back in 2005.
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lars

I remember you well from the TFB in NOVA - that was a fun event!

I have seen posts from people critical of pulling the PB vacuum off the PCV "T". I've done it on several setups I've done and I've never had an issue with it. I have even checked the PB leg of the line for engine oil residue after some time in service, and have found no problems.

Lars

gkull

I'm a long time demon carb person. They went through a period of time of poor quality control

They came with down leg boosters that were not perfectly perpendicular to the ventures they can be machined to correct that if you have that problem

I drilled holes in the primary blades to make the 4 corner af ratios more adjustable. I had the air bleeds setup on a flow bench

It is now very responsive even on big single planes