I've always wanted a copy of 'Smokey Yunick's Power Secrets' and after his recent passing (may he rest in peace), I was reminded that I had yet to make my purchase.

The book arrived today. I don't know of a better book with more 'straight-forward talk' other than 'John Lingenfelter on Modifying Small-Block Chevy Engines'. I like the writing styles of both. I hope John recovers to bless us with more of his knowledge and secrets.

The point in my posting this thread involves a subject that is of interest to me: Ignition timing. In my recent Dyno session, the tuner suggested that I may have a 'lazy' ignition curve as the engine appeared to be lacking some 'oomph' given the excellent combination of engine parts installed (which most recently produced 220hp and 280ftlbs at the rear wheels). The tuner, Race Related, suggested there is hidden power to be realized by laying down a new ignition curve. The last curve was implemented with the '882' casting heads, a leaky/tired carb and dual exhaust with cast iron exhaust manifolds. I have since added DART Iron Eagle heads, Hedmann Jet-Hot coated headers, a fresh dual exhaust and a Lars' rebuild and re-jet of my q-jet carb.

I've bought one of those new aluminum balancer covers to enable me to get a better (longer) reading of the timing with my adjustable timing light. I also have a fresh set of accessory drive belts as I'll be stripping down to the balancer to install the black proform cover.

Smokey wrote in his book that optimal spark DURATION is key to making reliable power; especially under load/WOT. My questions: How does the HEI ignition rate when it comes to spark duration? Can HEI spark duration be adjusted/extended? How does HEI compare with the MSD systems that improve spark duration.

Smokey also wrote that proper spark plug routing is essential with a minimum of .5" of gap between wires and any potential grounds (read engine or metal wire looms) to prevent cross-firing between wires. Is this a big deal even with stock silicone 8mm suppression wires? Should I be investing in some more wire looms to improve the routing of the wires at/near wires, engine, headers or is this overkill?

Thanks for your advice! :seeya

 

Have you installed Lars recurve kit? It has a very aggressive curve off-idle. It really helps my OD tranny work better at low rpms while in 4th. And I now have a mean chirp in my 1-2 shift whenever I punch the throttle!

I don't know about changing duration in the HEI setup, or MSD for that matter. Hopefully someone else can chime in.

With regards to the ignition wires, I wouldn't get too jiggy about it. I've noticed some folks get awful religious about plug wires, but I guess I'm still on the fence. Just replace them once in a while with good quality wires. The high heat environment of the C3 tends to shorten their lifespan.

 

Jacobs Electronics has a book on ignition that takes you thru a timing by performance procedure.
I think Smokey's book was written before the current crop of high performance wires. I'd be more concerned about clearance from heat with current wires than interference between wires.

 

MSD systems (all capacitive discharge systems, actually) have a very SHORT duration, with a high peak. This is useful for igniting a rich mixture, especially when using nitrous. The short duration is not good for lean mixtures typically found during low load. That's the reason they fire the plug multiple times at lower rpms.