Alright, I'm in the process of upgrading my ignition for several reasons, but the biggest is that I'm planning to make my car into a street/strip car. It's setup for just street now...

My current distributor is the MSD Street Fire HEI (wasn't my first choice... long story) on an aluminum headed 383 stroker. I recently purchased a MSD Digital 6AL CD ignition, but it got me thinking that maybe I should upgrade the ignition coil. I talked to MSD tech and they thought I should just stick with the Street Fire for now then when I change out cams, go for a higher quality Pro Billet one. My thought is that if I'm messing with the distributor now, I might as well fix it up.

So here's the options I'm considering...
1. Upgrade the Chinese made Street Fire with the MSD extreme cap and rotor kit and get the MSD HEI coil. This bumps up the coil's performance considerably, but 'm not sure if this is a good idea or not beause of the distributor quality. It does use what I already have and is the cheapest option I've come up with.

2. Replace the distributor with the Pro Billet HEI distributor. This is the most expensive option. Keeping the HEI coil puts everything in a nice package on the engine. However, since I'm using a 6AL, this is kind of a waste because you end up pulling the control board out of the distributor.

3. Replace the distributor with the Pro Billet distributor with external coil. The coil I was looking at using is the Blaster SS. This distributor doesn't have a control board and plugs right into the 6AL. It's also not nearly as expensive as the HEI version. The draw back is that I now have to mount the coil somewhere and use a coil wire (that can be a positive too).


Well, what do you guys think? Which is the best option for cost/performance? Or do you have better suggestions? You guys have given me pretty stellar advice in the past... Personally I'd like to stay with MSD. Moving to US made parts is generally a plus in my opinion.

 

I guess you don't want to hear that none of the stuff you've described will get you any additional power/performance.

Increased spark energy does not equate to increased engine output.

 

If you're going racing, you have other places to $pend money.

 

I agree with you guys. Increasing spark energy does not equate to any significant performance increase. Even going from a worn out ignition to a really good one, you would probably only see gains in the 1-2 hp range.

However, it does do many other things for you. One of the biggest gains that I've seen talked about is increasing fuel efficiency, and lets face it, a 383 can use as much of that as it can get. I'm already running an overdrive transmission with a 3.08 rear (wish it was a 3.55 or 3.70).


My issue with the distributor and coil I have really just comes down quality... That's the main reason I'm looking at switching. I'm just not sure which of the parts in it are lower quality. Looking at the coil's spes it would seem that is one of them...

 

I think you're chasing a ghost here - but I also think you've made up your mind.

 

Increased spark energy does not equate to increased fuel efficiency. Sounds like the spin doctors have done a number on you.

 

Maybe consider an MSD E-curve dist'r for the ease of customizing a timing curve if your going racing?

 

Spend the money in an area where you will see an actual improvement in performance.

 

I'm not familiar with the E-curve... I'll have to do some reading on them. Would that be something to use instead of the 6AL?


As for the people saying spend money elsewhere, it's already been done (suspension, steering, cooling, transmission, the list goes on...). The only thing for more performance that I could do is switch rear end ratios and switch to a higher duration hydraulic roller cam (running a hydraulic flat currently). Both of which are WAY more expensive than a simple distributor and/or coil change, and both of which are in my plans.

Those saying that increasing spark energy has no real effect, I'm not really sure what to say... I've spent several days reading up on the different types of ignition coils and how they work (and NO it wasn't from reading the info from the manufacturers). If you can point me to some data that shows that increasing the coil's available energy and recharge time doesn't allow you to increase the spark gap, increase spark intensity, and also create more accurate timing, please post it.

What I haven't been able to find is how a CD system utilizes the coil and how to pick a coil for use with a CD system like the 6AL.

Any comments on distributor build quality?

 

A stock HEI or well set up points distributor has all the spark accuracy needed for any engine.

The fundamental at work here is that a spark does not light the entire combustion charge, it only ignites the very few droplets of atomized fuel that happen to be in the vicinity of the spark. The remainder ignite as a chain reaction from those few. How well they ignite is a function of engine design, fuel atomization, etc. but completely unrelated to spark intensity. An analogy would be that the height a sky rocket reaches or the intensity of the burst has nothing to do with how the fuse was lit. Similarly, the max. temperature your cooking grill reaches has nothing to do with how you light the fuel.

If a spark is too weak to light off any of the mixture, that's a different story. As Lars has proven many times, a stock points and coil system from the '60s is more than up to the job.

 

If you can point me to back-to-back dyno runs showing that those items have a measurable impact on power production, please post it.

If the plug can fire, it will fire - and that's it. If the compression or RPM are such that you need more capacity in the ignition then fine...but unless you're making more than 1.4 HP/CID and turning past about 6,500 RPM...you're not there yet.

It's your money, spend it how you like.

 

I really like your analogies. Thanks for replying! And yes, pretty much any ignition will ignite fuel well enough.

And I do see your point, but not all the gas put into your chamber is ignited (thus part of the reason for exhaust recirculation). So not all of it can come down to a chain reaction from your initial spark. Burning more of the air/fuel mixture then comes down to timing and probability of gas particles hitting the spark.

By increasing the spark plug gap you increase the size of the spark and thus increase your probability of igniting fuel, but your coil has to be able to provide enough energy to ignite the larger gap. Additionally, increasing the energy between the contacts will result in a larger spark (it arcs even further than just the direct path, I can see if I can find the pictures if you like) which also increases the probability of igniting fuel. By reducing the time from spark to ignition (aka increase ignition probability), your engine can become more accurately tuned and thus more efficient.

This becomes even more important as your RPMs increase because the higher the RPMs the less time your coil has to recharge (supposedly what CD ignitions help with, but I don't know how the standard coil joins in with it). By switching to a higher performance cam, the RPMs increase. Like I mentioned I'm planning to switch out cams, which is why I bought the Digital 6AL (although I have also read several forum posts about 6ALs helping smooth out idle, which I do need).

 

As already stated, no one's expecting HP gains out of increased spark energy... Any gains will be very small on a dyno, but car and engine performance gains do not have to equate to HP gains. Heck, I could just lose some weight off myself and gain performance.

Yeah, I think I'd be looking at around 6500-7000 rpm and I'm estimating around 1.3-1.35 HP/CID. I'm currently sitting at about 1.1 HP/CID. When a new coil cost $60 and a new distributor with coil costs about $250.

We've pretty much gotten off point here... Does anyone think the StreetFire HEI distributor is good enough to handle a higher RPM engine? If so, ok... I guess I'll just stick with it until it dies.



However, saying that if a plug can fire, it will, is not accurate at all. If your not putting enough energy to it, the plug will not fire regardless of whether it's good or not.

 

I bought an accel 59107 when I did the carb conversion on my 84 c4 thinking it was a nice USA made dist. I must have missed the made in chinkastan labeling on the box. Have had no problems with it but will be putting an old gm hei on it soon as I have it recurved. And now I hear that the msd streetfire is hopsing made, go figure.

 

If the plugs are clean and the motor pulls hard all the way to redline then the distributor you have is good. Mixture, valve float, overlap, piston dome shape, etc are bigger contributors to performance (or the lack thereof) unless you are running really crazy compression and extreme top-end cams. The stability of the spark is key and as long as your current setup is in good condition then I personally would keep it. A good cap, rotor, and wires along with the right plugs set to gap equally are the real important parts for 99.9% of us.

 

It's 100% accurate. I noted impacts on this, but my point remains that better than good enough delivers nothing; not fuel economy, not power...nothing.

'nuff said - it's your Cool-Aid, drink away.

 

A stock HEI or well set up points distributor has all the time it needs on a 7K RPM engine to recharge adequately to prepare for the next spark.

Having a larger plug gap (which requires a higher level of energy to ensure proper discharge) may as a side effect ignite more fuel droplets than a smaller gap- but again this does not result in more complete combustion of the fuel. That's a function of engine design and fuel system characteristics. A bigger multi-spark zoomy-blasto unit will not obviate the need for an EGR or AIR system.

Keep in mind that a stock HEI unit can easily deal with a .060 gap. No engine build hardware you've mentioned using would be beyond the capabilities of a stock ignition system. If you just like 'bling', that's a different story.

 

I believe that coil is sufficient for what you are going to use it for. The module is also important as it controls dwell and controls switching on/off of the primary coil.
Just get a module that MSD recommends for that coil.

Better exposure to the spark may help in igniting fuel such as side gapping your plugs. The heat range of the plugs may have an impact on your fuel burn/ detonation threshold as well. To hot detonation, too cold fouling.

 

I have a Dodge Shelby CSX 2.2 turbo [modified]
It would not pass emissions.
I installed msd 6al & blaster coil. With on other changes it passed
vary clean. Also to run high bust above 15psi before I hade to reduce
plug gapes to 25. After I could gap to 45, with no miss fire
and better mpg.
So, cleaner emission, Able to run more boost, and better mpg
I run them on my vet, and truck
Just my experince

 

There ya go. More gap, more exposure, better light off and burn.

The new electronic MSD modules are nice in that they incorporate a rev limiter so if anything lets go in the drive train at least the engine may be spared.