View Full Version : Backfires from a stop

08-01-2003, 03:51 PM
I got my Digital 6+ in and it seems to have made more problems than it solved. I have the Pro-Billet ready to run in a 305 with a blaster coil and MSD 8.5mm wires. The itnitial timing is at 8 degrees with the defualt mechanical advance. It seemed to want to sputter and hesitate when I want to go from a stop but works okay at around cruise RPMs. When I installed the bypass, it still did it so I know it's not the box, but maybe the coil or timing. Please help!

08-01-2003, 08:09 PM
I advanced the timing to 19 degrees and it seems to be working okay, just some mild det. when I put my foot into it. So I'll back it down to about 17 or 18.

08-02-2003, 09:55 PM
I backed down to 17 degrees and it seems to have plenty of power and no detonation when hill climbing. But as the engine got to about 180 degrees, the car seemed to want to stumble from a stop, it would still go just sputter a little then a big sputter then it would act okay and speed up. When I let it cool down for about 15 minutes it wouldn't do that until about 5 minutes of driving. I'm thinking about putting the black bushings in the distributor and advancing the timing to about 20 degrees but I don't know if that will do it. Any advice will help. Thanks

08-03-2003, 07:18 PM
Have you changed the distributor springs that came installed on the distributor? The MSD Distributor comes with the two heaviest springs installed. The distributor is supplied that way so that when it is first installed it will not cause detonation problems from advancing the timing to fast. In your case, it sounds like you need a slightly lighter spring. Try the two Blue springs and that should make a difference.

MSD Tech1

08-03-2003, 10:04 PM
I ran the car today with heavy silver springs down the free way. I seems to struggle only when I accelerate from a stop and acts normal when I am at about 2500 rpms or higher. I replaced the two heavy springs with the two blue ones but it has seemed to make it worse. I bypassed the box and it went back to like it was with the silver ones. When I accelerate, I can hear small pops coming from the exhaust. So now I am still puzzled! I know that the box is doing something, it's just doing the oppisite of what I want it to do!

08-03-2003, 11:17 PM
I looked on Demon's website and they said to increase the idle mixture and if that didn't cure the problem to increase the float level. Do you think that will work? Or do you think it's all ignition?

08-04-2003, 01:29 PM
I think I got it figured out, I replaced the blue springs back with the silver ones and I adjusted the idle mixture so it was a little more rich and it has seemed to fixed the problem. I tested it in my driveway by putting it in drive and holding the brakes as I accelerated the engine. I couldn't detect any backfire or pops up to 2500. I didn't want to go any higher than that. :)

08-04-2003, 06:15 PM
That's good! Sounds like it was just to lean and needed the extra fuel.