Better spark

[tahiti190]

Have a 70 GTX with 69 440, 11.5 to 1, decked with 906 heads, 509 purple shaft, 950 deamon, Hookers thru flowmaster 3" all the way back-727 with shift kit. MSD 5 (5200) Promaster coil #29440, unknown distributor, accel wires.

PROBLEM: she runs like crap and loads up at idle-once cruisin seems to be ok.Hard crank hot.Should I change ignition system?

 

[rlsbee]

I'm not an expert at this stuff but here's a few things that come from experience.
I'd check some other things before you change the entire ignition system. . Where's the timing, initial and total, set? Since you said the distributor is 'unknown' this could be a source of timing issues. I usually like to set total around 37 to 39 degrees (vacuum disconnected). This is dependent on the quality of gas you can get. If the distributor has too much centrifugal advance built in, you may not have enough initial timing for that cam. The solution is to take out some centrifugal advance so you can increase the initial. This can be done by modifying the distributor, which is best done on a distributor machine or replace the distributor with one that has provision to limit the centrifugal advance with bushings or stops. On this subject, I can't give you any better advice than to read the following 'white paper' called ignition 101:

http://www.diamondbackengines.com/technical-white-papers/ignition-101/

That article was very helpful to me and it may be for you also.

To me, that 950 Demon carb seems like a lot for the street. Do you know anyone with a 750 that you could try?