Break up under 3000RPM
Ive got a 1200PA on my 289 with a single turbo, MSD 6AL-2 controlling timing. My issue is if I get into it under 2900-3000rpm it breaks up almost like its on the two step, and after that its runs like a scalded cat. Any ideas to look at? Ill try and post a log in the next few days, but being the holidays life is hectic.
Rotor phasing?
I have an msd 6530 box controlling timing and dont think that the rotor needs to be phased. If iI'm soft on the pedal it doesn't break up, only under load.
Datalog is your best bet.
Are you in vacuum or boost? Is it at the transition from one to the other? Can you put it into boost at a lower rpm and then let rpm climb under wot and it still breaks up there? (I.e. trans or foot brake into boost and make a wot pull) what are your afr targets at 45 and 90kpa for 1100 amd 3000rpm?
Quote from TurboMerc on November 22, 2017, 9:40 pmI have an msd 6530 box controlling timing and dont think that the rotor needs to be phased. If iI'm soft on the pedal it doesn't break up, only under load.
I have done 2 with a 6530 box and did not phase the rotor on either. Both run great.
Looking for simple here. What do your timing curves look like? This just seems like an ignition problem to me.
I was looking for simple also, I played with my timing curves both advancing and retarding the curve in the trouble area with no change in the issue. But today while messing around and checking my phasing (hole in a stock cap) I noticed I couldn’t see the rotor part of the time and that I could see it in other places (using a timing light on selected plug wire) I’ve seen other people do it and you should see the rotor steadily on that post. I’m also using a stock distributor with petronix acting as a Hall effect for the msd 6530. I’m at a loss on what is causing this.
It's always the ignition. First thing is put a set of points in it. The MSD wont' care, all it is looking for is a trigger. I would also set the spark plug gap at .035 just because it is a boosted motor. So far I at least have not cost you a lot of money. Try a different coil. When it is running grab the spark plug wires with a bare hand..... just checking for voltage leaks! 🙂 I usually measure how good the spark is by how far the shock runs up my arm. (joking here but I have accidentally tested this way) Seem weird that the problem occurs at the point the MSD switches from multiple sparks to single spark. OK out of ideas for now. Good luck.
That's strange... I have a 331 that's supercharged and it does the same to me. It breaks up around 3200-3500 rpm after which it runs amazing. I've played with the spark map a little, changed to MSD wires, and gapped plugs 3923 down to about 0.032". Haven't tried it yet since its been around 10 degrees out
Have you you made any progress?