KNOT-RIGHT

To boost reference or not.

My understanding of boost reference is to relocate the power valve vacuum signal from above the supercharger
to below it.

This thought has been bothering me there have been several posts concerning this.

Just do a search on boost reference and you shall see.

Considering the procedure you are about to see I decide to boost reference the following carbs.

This is the way I decided to do it. It does not mean it is the only approach just the one I went with.

Im sure there are others who will comment on my procedure but this is the way I did it.

Please do not hold me responsible for any of the following. In other words Attempt this at your own risk.

This info is provided for educational purpose only.

Remember this is specific to this demon carburator.
Power valve on primary side only.
850CFM street demon.


Gerry

KNOT-RIGHT

on the primary side of this carb behind the meetering block there is the power valve chamber

three holes are apparent one (center one) is pluged by one of the philips head screws holding the base plate down. the smaller hole to the right makes it way to the base plate but yet it is not used.

The one we are concerned with is to the left this is
the vacuum source for the power valve we must relocate.

KNOT-RIGHT

remove base plate removing 6 philip head screws.

located under carb

KNOT-RIGHT

this is a shot of the center base phillips screw you just
removed. located normaly under the primary power valve chamber. You should see two small holes and of course the threaded hole you just removed the phillips screw from.

all of these holes including the threaded hole lead to the power valve chamber the two small holes must be pluged. Of course we dont need to plug the threaded
hole because the philips screw you reinstall will do that for us upon reasembling the base.

KNOT-RIGHT

fliping the base over meaning looking down on it the way it would sit on the engine reveals a brass
check valve. Power valve protector in the event of backfire. This is removed by fliping over once again and looking into the smaller holes and finding the one that is centered to it. and lightly punching it out. I used a fliped over 3/32 drill bit. taping it with a small brass hammer.

KNOT-RIGHT

it should look like this when it comes out.

this is no longer used so if you get a backfire lator and you start following plugs ya might wanna check your power valves.

KNOT-RIGHT

The base plate should look like this now.

This is looking down on it the way it sits on the engine

KNOT-RIGHT

Now here comes the scary part looking at the base plate
from the side view. scribe a line spliting the hole in half
this is to establish a center line of the hole.

measure twice.

after scribing the vertical line I chose to scribe a small horizontal line. This is centerpunced .

Then drill a pilot 3/32 hole through this punch mark.
it will intersect with the original power valve vacuum
source hole.

You can view your depth easily by looking down the original p/v vacuum source hole.

KNOT-RIGHT

I chased the 3/32 hole with a number 23 drill which is slightly smaller then my brass tubing I purchased from
mcmaster-carr.com

KNOT-RIGHT

now I cut my brass thin wall tubing to a lenth of approx 1 inch. and with a liberal amount of Locktite red.
I gently tap it in taking notice of mt depth. Making sure I dont bottom it out. Again this is easily visible looking down the original p/v source.