You guys running Demon carbs, where do you hook the brake booster line?
08-12-2004, 08:23 AM
#1
Melting Slicks
Thread Starter
You guys running Demon carbs, where do you hook the brake booster line?
Looking to switch to a Demon carb but not sure where I will hook the vacuum assist line. The Edelbrock's have a fitting on the rear but the Demons do not.
08-12-2004, 10:25 AM
#2
Tech Contributor
I had the same question a couple of weeks ago installing a Speed Demon. The edelbrock intake has a vacuum port but it's blocked by the heat sheild and rear carb bowl. I ended up using a tee in the 3/8 rear vacuum line out of the carb. The PB and PCV are tee'd off that. It works but I would have rathered used a separate line for the PB booster. The stock GM LT1 intakes solve this by having the intake vacuum port offset to clear the Holly carbs. I wonder why Edelbrock doesn't redesign their intakes to account for this with the number of Hollys and Demons on the market?Edelbrock sells a short 90* street elbow that's supposed to fit under a Holly bowl but then you would have to cut a hole in the heat shield if you're using one.
Gary
Gary
08-12-2004, 10:50 AM
#3
Melting Slicks
Thread Starter
I am using a 2 inch spacer but that port is being used for the accessory line and a vacuum line for the Turbo 400 trany. I guess it is possible to drill and tap the intake and install an NPT fitting.
08-12-2004, 11:02 AM
#4
Team Owner
My 750 Speed demon
right under the rear bowl is a 3/8th fitting. It's so tight up against the metering jet block that it's hard to push on a 3/8th rubber hose.
So me being a smart guy I ground the block for clearance. If you look at the rear metering block. It has a machined lip that holds the block to bowl gasket. I ground the block down to within a few thousants of the edge of the lip.
So me being a smart guy I ground the block for clearance. If you look at the rear metering block. It has a machined lip that holds the block to bowl gasket. I ground the block down to within a few thousants of the edge of the lip.
08-12-2004, 12:14 PM
#6
Le Mans Master
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I have the brakes running off of a small fitting in the intake. I have the pcv valve running off of the fitting on the carb.
08-13-2004, 07:16 AM
#7
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I went to a hardware store and bought a 90 degree brass pipe fitting. There is an external and internal threaded part. The body of the fitting is square. Gave me all the clearance I needed under the rear bowl. You want full manifold vacuum for the brakes and if possible you want it to be a deticated line, no tees. PCV goes into the back of the Carb.
