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View Full Version : Edelbrock RPM Air Gap.....design flaws



buns
12-19-2007, 10:16 PM
Flaw #1......The threaded hole for a vacuum source is smack dab under the rear float bowl of my Demon carb. I measured a Holley and the float bowl is not much shorter. Anyone have any idea why they did this? Is their an alternative vacuum source?


https://static1.pt-content.com/images/pt/2007/12/vetteprochargerintercoolerandupd2-1.jpg




Flaw#2.....Not entirely Edelbrocks fault, but the inlet for my Demon carb is smack dab inline with the threaded hole for my heater hose connection.


https://static1.pt-content.com/images/pt/2007/12/vetteprochargerintercoolerandupdate-1.jpg



Wondering if I could use this hole for the heater hose connection...


https://static1.pt-content.com/images/pt/2007/12/vetteprochargerintercoolerandupd1-1.jpg

ZZ430
12-19-2007, 10:44 PM
If you could use a 1/2 phenolic spacer under the carb it would make things much easier.

Edelbrock makes this low profile vacuum fitting for power brakes .

http://store.summitracing.com/partdetail.asp?autofilter=1&part=EDL%2D8096&N=700+115&autoview=sku


And Earl's has this 90* heater hose fitting.


http://store.summitracing.com/partdetail.asp?autofilter=1&part=EAR%2D984208ERL&N=700+4294849622+115&autoview=sku

eville
12-20-2007, 08:53 AM
I had the same problem with the fuel inlet on the Holley. I wound up using the heater hose fitting on the other side by #1 cylinder. Not sure if that will work for you.

CarlC
12-20-2007, 09:13 AM
Common situations for everyone.

I used the water tap where you currently have the brass fitting and 90* aluminum fitting. A lower-profile 90* fitting without the aluminum adpater + brass that you have may make overall fitment better. Mine is angled such that it points almost to the RHF corner of the car.

You can use the rear water outlet. If you do I suggest using a 5/8" hose with a preformed 90*molded into it. Good auto parts stores will carry these. Gates make a universal part, but one from another car can easily be adapted. This should make installation cleaner and less stressful on the core connection. I use the preformed 90* on my A/C car since the lower attachment is a bear with little room so the hose is overly stressed unless a 90* is used.

Zee
12-24-2007, 09:20 PM
looks like there is a an allen head plugged port in the base plate of your Demon under the rear float bowl. Not sure if there is enough room for a hose barb to be installed there. If not, there are 1/2" spacers with vacuum ports.

buns
12-25-2007, 12:37 PM
Zee....good eye! I new these large pictures would help. I didn't see that. I will give that a try as I can't use a spacer under my carb, I already have less than zero hood clearance.


And thanks to all that replied. Much appreciated.

Rolling_Thunder
12-25-2007, 07:14 PM
There's your problem... you're using a Demon carb...

Steve68
12-27-2007, 01:34 PM
Edelbrock intake designed for a Edelbrock carb, told them about this when I put a Performer RPM on in the mid 90's, they said good idea!

Tom 72RS/SS
12-27-2007, 06:39 PM
I had the exact same problem when I switched from the Edlebrock to Holley. Nothing cleared, fuel line ran into the heater hose and the port in the back of the intake barely cleared the fuel bowl after it was plugged.
So after talking to several people (including the local hot rod shop) the final solution was a carb spacer with built-in vacuum port for the power brake booster.
Problem solved right? Not so fast, that led to another issue - the stock accelerator cable was now too short. UGH!
Had to opt for the Lokar style adjustable (cut to lenght) braided cable & bracket. I have a cowl induction hood so no clearance issues there. Whew! Glad that's over!!

buns
01-09-2008, 09:14 PM
https://static1.pt-content.com/images/pt/2008/01/update-1.gif

Well, I got my my fuel line problem solved. Now that I am more familiar with AN fittings. Turns out, all I needed were these -6 45 degree elbows. They are XRP from Good Vibrations Motorsports (good prices on XRP stuff).

https://static1.pt-content.com/images/pt/2008/01/vettedemonfuelline-1.jpg

eville
01-10-2008, 11:53 AM
dude nice solder on the copper pipe. *lol*
U gonna insulate those hot water pipes?
Nice work on the fuel line. Apparently oven cleaner will remove the ugly blue/red finish when soaking the fitting overnight.

CarlC
01-10-2008, 01:15 PM
You may want to reconsider using that copper pipe. Without a flexible connection the chances of fatigue failure, especially at the heater core fitting, are high.

70bird
01-10-2008, 01:24 PM
You may want to reconsider using that copper pipe. Without a flexible connection the chances of fatigue failure, especially at the heater core fitting, are high.

+1
and electrolisis, if the copper is touching steel anywhere.

buns
01-10-2008, 07:33 PM
dude nice solder on the copper pipe. *lol*
U gonna insulate those hot water pipes?
Nice work on the fuel line. Apparently oven cleaner will remove the ugly blue/red finish when soaking the fitting overnight.

Thanks for the tip on the oven cleaner. I was trying to figure out how to get rid of the blue and black on the fittings.

As for the copper pipe......well, I knew I should have removed them for the photo shoot. A plumber I am not. They are just for mockup and will be replaced with stainless steel.

buns
01-10-2008, 07:41 PM
You may want to reconsider using that copper pipe. Without a flexible connection the chances of fatigue failure, especially at the heater core fitting, are high.


Not to worry. There will be hose on each end of the pipes. Stainless steel mandrel bent elbows are $30.00 each so I figured I would mock it up in copper first.