Help with carb tuning problem
Thread Starter
Teching In
Joined: Mar 2005
Posts: 22
Likes: 0
From: Nash TX
Help with carb tuning problem I have a Demon mechanicla secondary 750 CFM carb on my truck. Just got it on last weekend and I am in the process of tuning it. I have a little problem with it stumbling with slight transitions in throttle with the torque converter locked up. My combination is as follows 385cid SBC with ported sportsman IIs and a Victor Jr. intake MSD billet distributor set at 14 degrees initial timing 36 total. It happens when I am cruising part throttle and have to give it a little gas to keep speed up say going up a hill or something like that. I am not sure exactly what it could be but I am thinking that I need to go with a different accellerator pump cam. I have the stock cams on there right now I believe they are the pink ones. Any suggstions?
me and my friend both have demons and both had to have work done. both ran lean under acceleration so we put the most aggresive accelerator pump cams in and drilled out the squirters.hope that helps.
TECH Enthusiast
Joined: Feb 2004
Posts: 743
Likes: 0
From: Foley, Alabama-southern Alabama
Try A Different Powervalve You might want go to a lower number powervalve in the primary meteringblock maybe a 6.5 or so,I don't know what gears you are running but sounds like a pretty stout motor that likes more rpm then your are running it.Also be sure and check your float settings and idle screw setting first!!! 
Thread Starter
Teching In
Joined: Mar 2005
Posts: 22
Likes: 0
From: Nash TX
I changed my PV from a 6.5 to a 4.5 and no difference. I am wondering if it is running off the power valve circuit all the time because I am definately not getting any extra fuel during the sudden vacuum signal loss that occurs when you slightly open the throttle. I know my vacuum at idle with no load is around 9 inches and at idle in gear it is about 6. And from what I've read the power valve should be 1.5-2 inches below at idle in gear.
