L-82kid

Hello,

I have a 750cfm speed Demon on a 350 with a magnum 280 cam. I set the idle at 850rpm and if I let the car sit and idle within 30-40seconds the idle slowly drops. After a few minutes of sitting the idle will be stalling out. If I set the idle at 1,000rpm it will take about a min to drop back to 850rpm. So I get the idle when I want it and by the time the traffic light changes my idle is too low.

Has anyone experienced this problem before? its really annoying

Thanks,

L-82Kid

gkull

Is this a new adjustable air bleed model? Do you have enough exturnal spring to snap the throttle shut?

L-82kid

Its an older model without the adjustable air bleed. I thought the same thing about the springs, I'm pretty sure the throttle blades snap back all the way.

gkull

To get my 750 speed demon to run correctly all four throttle blade have a .085 hole drilled in them to lean out the idle. The x-fer slots are cut taller the rear air bleeds have been changed.

As for your problem I would first check for a vacuum leak. Plug off all three demon ports Two on the side and the 3/8th under the rear. See if it exhibites the same problem while warmed up.

Set the idle speed with more secondary opening. You must maintain @ .020 showing on the x-fer slots just like the directions say.

varkwso

I had nothing but heartache on a new road demon carb on my son's 78 Nova. It ended up sitting in a box waiting to be sent back to Dahlonega to have them fix all the leaks and problems. It poured gas at idle and fouled plugs daily.

Great looking carb - has not worked out well at all for me...

73jst4fun

Take the entire carb apart and check for aluminum shavings from the CNC machining, tighten all of the screws, make sure the transfer slots are at .20 I had to do this with several of their carbs and found lots of shavings as others did also, not the best QC from BG. look for some past posts on this topic...