Ive never ventured into ignition systems that much. I know how distributors work and all. But, On my 383 build up, Im goin with the "standard" MSD dist. and blaster 2 or SS coil. But, what exactly does the 6AL do? I mean, do I need it? Can the motor run without it, and just use the dist. and coil? I didnt know if since my motor is gonna be carb'd, if there still needed to be some kid of computer to run the ignition system.

 

An MSD box is probably one of the last upgrades you need, unless you're running at high RPM or high cylinder pressures.

You'll need a non-computer HEI distributor.

 

dito

 

10.75:1 CR runnin CC XE274-H 230/236@.050. Not sure how high cylinder pressures are gonna be, but Im kinda concerned with detonation. 10.75:1 with iron Vortecs, seems kinda high. But most guys at my shop are tellin me as long as I dial in the timing right, there shouldnt be a problem. Redline for the motor will me a smidge over 6k

 

10.75 on iron heads seems pretty high. I'd be expecting detonation problems.

 

So whats a good distributor to go with? Are pretty much all MSDs made to work with their ign. boxes?

Im just worried that with appx. 10.75:1 CR on iron heads, Im gonna nead some good ignition components. I didnt know if the multiple spark would help me, or the capacitor thats int he box would help prevent knock . Any suggestions?

 

Any non-computer HEI distributor from 1975-up can be made to work on its own, or with the MSD box.

The MSD box will do nothing for knock prevention. All it does is give you a hotter spark that will be more likely to ignite the denser mixture in a high-compression chamber, and since it's a capacitive unit, it has a shorter recovery time for better high-RPM performance.

Don't be fooled too much by the whole "multiple spark" thing. A capacitive discharge system has a very short spark duration, but a fast recovery time. An inductive system like the factory HEI has a long recovery time, but also has a long spark duration. At low RPM, the CD system needs to fire multiple times to equal the total spark duration of the inductive system. There's no performance benefit from it. Above something like 2000 RPMs the MSD is back to single sparks anyway.