I came across this forum while looking into a FI to carb swap for a customer of ours over here in the UK.

Looks like we got everything all figured out thanks to the info here.

What I did notice after reading a huge amount of threads is a lot of people are having trouble with Demon Carbs running rich, if the carb is the correct size for the motor and the correct series then this is usually down to timing.

Anyone having tuning problems with a Demon needs to call Don at FBO Systems in Oregon here FBO Systems main page, Ignition and Carburetion Professionals, FBO Ignition systems, Ford Ignition, Mopar Ignition, Ford Distributors, Mopar Distributors, Ford distributor curving, Mopar distributor curving, HEI Ignition, ignition tuning, ignition tune up

Don has an excellent tuning guide wrote for Demons

Hope this helps

 

that would be cool, i know there are a lot of us who have had problems with the demon carb, i think mine is about worked out but def worth checking out

 

Glad to help

I'm the European dealer for FBO Systems so any Demon tuning enquiries over here I sort out, you guys in the states Don is your man.

What's happening is as the duration @050 increases the effective low RPM cylinder pressures decrease due to valves being open for longer on each revolution, this decrease in cylinder pressure means the fuel becomes less volatile, and will take longer to burn so the spark needs to be fired earlier. The other side of this is if the cylinder pressure is too high then fuel becomes volatile enough not to need a spark (detonation)

If ithe plug is not fired off early enough unburnt fuel is pushed into the exhaust giving the appearance that the carb is way rich, this can also cause overheating problems as the fuel continues to burn in the headers which is like having 8 blowtorches burning under the hood.


This usually means a recurved distributor as to increase the initial without keeping the total down to each motors ideal will result in detonation.

Demons are easy to tune but the rule is always ignition events first for the motor, car and application then tune the carb to that, once the ignition is right you can baseline the carb then use the plugs to fine tune using indicators on the ground strap, porceline and threads

 

Isn't he like one of the baddest freakin' tuners in the country?

Is he the Guy I see in National Dragster all the time?

........that runs that 10 second all iron, all Motor, 318 Mopar, that stomps all the Big Block Mopar, Ford and Chevy guys?

.........with all those Wally's across his desk?

.........has spent his whole life (40 years so Far) tuning ignition and carburation?

........can tune a tenth out of almost any car with the flick of his magic screwdriver?

........you don't ever want to meet in 1st round....ever!

Winner of the Mopars at the Strip 2006, NW Mopar Nationals 2006, National Dragster Challange 2006, has won at 4 of 5 tracks this year, 2005 Pro Track Champion, 2005 ET Challenge Pro Champion....and on and on.

Yup that's the guy I'd listen to, the proof is in the Pudding, or as you English people would say the "Spotted D_ick"...LOL

Get the truth, get the book!

Demon Tuning Guide

 

spotted.. lol wtf.. 10 dollars hmm I think I'd have mine figured out before that book ships to me. If I saw it at a parts store or a speed shop I would buy it there. Maybe someone should sell our parts stores 100 copies of those books.

 

Redbird..... spotted d..k is a real actual pudding over here in England

The FBO tuning guide usually ships by email so most people are reading it within 3 minutes (depending on connection speed)

No point selling it to parts stores or speed shops as they would just mark up the cost, so $10 then becomes $15/$20 the only loser then is the guy that wants to read it