carb help

[d2racer]

hey guys , got a problem with my car recovering on the shifts ?

quick facts
88 mustang , 3045 lbs with me in it
4.10 spool rear , southside bars and 50/50 drag shocks
mitey mite c-4 with a 4 grand ati converter
junk yard 302 short block , "F" cam and small valve edelbrock heads , msd dist and ignition rpm air gap intake and 650 demon by a reputable shop
shorty headers , 2&1/2 x-pipe and hooker aero-mufflers
launch at 3000 shift at 6100

cars been 11.90/113 in good air , in the heat its 12.teens around 110
1.66 to 1.70 60 ft
trying to run 12.0 in the heat ?

on the shifts it drops from 6100 to around 4800 , and seems to struggle to pull back past 5100 rpm then climbs okay back to 6100 and crosses the stripe around 6250

not sure how to make it recover on the shifts quicker ? never played with air bleeds before but its seems an intermediate circut problem ?
the carb was a freebie and i know the story on demons , thinking of just buying a 650 or 750 hp holley or pro systems
ideas???

thanks

[PONY GUY]

you might have fuel boiling over in the bowls . Does this only happen when its hot or all the time ????? If it only happens when its hot try adding a carb spacer. Also check you the float levels and mixture. they might need to be adjusted . Also check your timing and pull a plug to see how the car is running . I run a HOLLEY DP 750 and other than quick fuel thats all I'll run . I heard too much bad stuff about Road Demon carbs

[Oldsmoduck]

Ya. try raising the fuel level.

did it always do this, or something you just noticed?

[d2racer]

its something that i think has been there since i switched to a carb. but i think its become more noticeable as i've refined the car and sorted out the suspension .
i already have raised the fuel level up to the middle of the sight glass with no change , the pressure never drops on the run and the plugs only look slightly dark
i'm thinking its too rich and loads up a little on the shifts till it burns off the load but now i find out that freackin demon carbs don't use reg holley jets???

talked to the guys at pro systems and quick fuel and they both felt thier carbs were overkill for my application , nice to see they were not trying to just sell me something . both techs said in so many words that the demon carb was the problem and that i should call holleys tech line for a recomendation ?

guess its time to order an hp holley carb

[adamsvega]

alot of demons have demons but all can be exercised !! a 650 is not too big for 4.10 geared 300 cubes 3000 # car .is the throttle crisp when hot for a dead idle. ck. for the anti siphon needles below the shooters. your converter has to be above 3K ???? most heat problems are off the starting line unless the line to the carb is getting boiled it in the carb. alot of demons have the small emulsion jets fall out or screwed in to far and blocked off .
if raising the float had no effect what so ever than cheak the power valve and its rate .next make some j hooks out of wire to insert into the airbleeds to close them up and test .if closing int. and h/s air bleeds off you can open the up with a small drill to + the area you blocked off .. how big is the fuel system behind the carb a lay down can be the bowls going to low .also air flow to carb can be very ragged / restrict /hot and work the mixture crazy . keep me informed .

[d2racer]

hmm , good info , but i got pissed when i found that most all the shit i have for holleys don't screw into the demon so i bought a pro systems 750 annular booster for about $20 more than a stock hp holley

just bolted it on , it started and idled much quicker and easier , seems a little rich in the garage

got 67 front with a power valve so thats really 77 and 76 rear , i would think it should be closer to 72-74 square in the heat but we will see tomorrow nite at index race

got all my holley stuff in the truck and we will try a pass and then jet down from there

[Gameracing]

Jet extentions on the secondary side has been known to cure this symptom.

[d2racer]

went to a pro systems carb , does not happen and car does not drop off as much on the shifts , used to fall to 4800 now only 5100 . and its a tenth and change quicker!!