CD boxes are for racing, at high RPM, boosted, NOS, etc.

A quality electronic ignition is fine most street rods.

 

It is a high rpm and timing control thing mostly for computer controlled adjustment.

70's HEI technology is good till 4500 to 5500 depending on the advance unit and initial timing.

If the thing has a mostly stock carb good chance stock HEI is more then you need.

The only thing from MSD I trust anymore is the wires. Many better companies out with a much better product.

I just did some research online (and as stated above) and it seems that the control boxes deliver the multiple sparks at lower rpm, so why do y’all say it for high rpm and race applications?

 

MSD stands for Multiple Spark Discharge. This is not just a CD box. It is designed to fire a number of ignition spark pulses in rapid succession for each cylinder to ensure that one of them lights the charge. One can argue the real world benefit, but that's been their whole claim to fame.

 

I'm not a big fan of multi spark ignitions or even capactive discharge unless you're running racing level compression ratios, or lots of boost be that laughing gas or supercharge of some type; or as a total flip, SMOG heads and low compression with a wide squish/quench and incorrect mixture from too lean to excessivly rich. For a normal street performance engine for the money they deliver far more bragging rights than power. The price of these things for the street is better spent on more sophisticated combustion chambered heads and piston crowns, more attention to details of crown clearance, gasket thickness, valve train parts, surface qualities, etc. than mega-buck ignitions.

Then again if you got all the 'right stuff' and some extra money then buy an exotic ignition; on the other hand if you don't have the 'right stuff' in the build don't expect that a mega-buck ignition is going to 'make a sow's ear into a silk purse'.

Bogie

 

So Bogie what would you recommend ? My engine is a 383 with e-tec 200 heads, edlebrock, airgap dualplane intake, 650 avs2 carb, about a 10.5:1 compression ratio. If I need to pay a little more to ensure I have a good enough spark I feel like that’s fine.

 

The MSD produces full power multiple sparks for each firing of a plug. The number of multiple sparks that occur decreases as rpm increases, however the spark series always lasts for 20° of crankshaft rotation. Above 3,000 rpm there is simply not enough "time" to fire the spark plug more than once, so there is only one powerful spark.

 

It is a high rpm and timing control thing mostly for computer controlled adjustment.

70's HEI technology is good till 4500 to 5500 depending on the advance unit and initial timing.

If the thing has a mostly stock carb good chance stock HEI is more then you need.

The only thing from MSD I trust anymore is the wires. Many better companies out with a much better product.

Please See above

 

It is a high rpm and timing control thing mostly for computer controlled adjustment.

70's HEI technology is good till 4500 to 5500 depending on the advance unit and initial timing.

If the thing has a mostly stock carb good chance stock HEI is more then you need.

The only thing from MSD I trust anymore is the wires. Many better companies out with a much better product.

 

I like the DUI 12720bk

 

I have ran a msd box for over 8 years and ran the hei distributor without one and honestly at least for the way the engine runs I never noticed the difference in anything such as starting and also how my plugs look during tuning and checking them etc and as far as higher rpm goes I have no difference between a basic summit hei distributor or running it with a msd box.

The main reason I get the msd box is because I like the rev limiter. My old skip white ebay special hei distributor it has the same components in it and its over 8 years old and I sold that motor almost three years ago and its still going strong with all original components that it came with minus the coil and cap I had to replace cause of my error. I put around 5000 miles on it and the new owner has driven it everyday so it at least has over 10,000 miles plus on it and it still runs like a top the last time I saw the guy I sold it too.

So for something that your not racing or taking to the track and just a everyday driver and if your careful and don't get the rpms up to high the hei by itself is more then good to make things work well. I just like the rev limiter part more then anything else and for me its worth it but I don't have it for bragging rights and it does not make my engine any better then with it or without it. I forgot to mention I had two different trucks one with the msd and the other without.

 

the multiple spark function is more of a gimmick, the capacitive discharge is what helps light a mixture in a high output application

Think about the multi discharge spark....... if the first one is per the timing setup, then each of the following discharges are retarded relative to the first. Possibly a span of 20 degrees behind the first spark to the last. Just logically it does not make sense to create several flame fronts over a span of 20 degrees. It would seem a single big spark is more effective working on the piston at one point in time at the optimum time.

On another note I’ve always used point ignition on street cars until recent. I made my own small diameter HEI distributor. And also use a modern weird shaped coil. The pick up, reluctor, module, and coil are standard auto parts pieces. Since redoing the points distributor to HEI I’ve noticed ease of start and the idle at the same advance and carb settings is about 100 RPM ‘s faster. Same everything else plugs and wires, just change from round coil to the modern “E“ type. I was able to idle it back and all else seems a bit (seat of the pants nothing scientific) smoother and stronger. This is just sharing my results of my HEI system.

Interesting. I'm still running an MSD box made about 20 years ago. I had it checked by MSD about 15 years ago and no issues. I feel like most of the MSD issues stems from poor wiring jobs or weekly wash downs and vibrations. When it goes I'll replace it with another Jacobs unit like the other car. It's also never faulted either.

Interesting. I'm still running an MSD box made about 20 years ago. I had it checked by MSD about 15 years ago and no issues. I feel like most of the MSD issues stems from poor wiring jobs or weekly wash downs and vibrations. When it goes I'll replace it with another Jacobs unit like the other car. It's also never faulted either.

It can’t always be that, the guys on here gotta know what they are doing. My feeling is the current available boxes on the market are not of the same quality as the older stuff.

I’ve seen more guys at the cruise that remove or replace “boxes” because of intermittent functioning. My guess they are newer acquired just because the cars are fresh builds.

Yep, its been in the last 10-12 years or so....whenever it was that the same investment group that owns Holley bought up MSD during its buy-up spree. MSD quality has taken a big hit since.
A lot of guys were pissed just a few years ago when Mallory Ignitions was also bought up be the same group, knowing Mallory's traditional quality and reliability would take a hit or the brand would disappear forever.....and that is basically exactly what happened...most of the Mallory line-up is now discontinued.

I've got one early 1990's vintage MSD 6A box, and several friends do too that still work fine. Some retard boxes too. One friend has however had trouble with a newer digital retard and newer small cap blower/tunnel ram "tight clearance" distributor.

I've been using Holley Pro Strip Annihilators, but they are no longer in production either. Can still be found as new old stock occasionally on Ebay or similar web auction sites. Either with a crank trigger or using a gutted Accel Blueprint HEI with just the mag pick-up inside for the spark trigger.

If I had to buy new today, it would be Daytona Sensors CD-1 or F.A.S.T's continuation of the Crane Hi series boxes.

I just did some research online (and as stated above) and it seems that the control boxes deliver the multiple sparks at lower rpm, so why do y’all say it for high rpm and race applications?

The need is in engine configuration, I write extensively about this including here.

When you use the basically correct design of parts as you did, multiple spark systems don't buy any performance. They are designed really from back in the days of lazy combustion chambers that for mechanistic reasons were not consistent burners, in other words these SMOG era heads generally under advanced ignitions, weak mixture ratios, and weak inductive ignitions combined to encourage low speed (RPM) miss fires. These are also part of big cams in slow turning engines. Big cams let's say over 270 degrees at zero lift to zero lift as a place to start don't run the engine really well under the cam imposed torque peak RPM. There is a lot of reversion which lowers the trapped actual compression pressure, mixtures specially from a carb go crazy, and the list goes on. So getting a burnable mixture between the plug's electrodes gets to be iffy at any instant, so hitting the plugs a few times reduces missfires. That's their only job, thete is no intrensic power gain accross the RPM spectrum because the plugs get multiple jolts. But for crappy combustion chambers and big cams especially when these meet on a rules spec race motor multiple sparks can really clean up the idle and low RPM performance.

Modern chamber and intake porting design has massivly increased chamber turbulance for high mixing of fuel and air into a uniformly combustable mixture. Additionally, these chamber characteristics specifically inject the mixture to stand before the spark plug so there is a trapped quantity of mixture ready to burn when the spark is applied, so once is enough. Therefore, multiple sparks don't show any missfire reduction in modern chambers. This function is the squish part of squish/quench function that I talk ad-nauseam about. Get this right and the rest of getting a good light-off, fastburn, and high detonation resistance, along with max posdible power and fuel efficiency for the overall configuration just falls inline. It sounds like you picked the right parts so this engine should be good without costly trick ignitions.

Time to recharge a single coil that feeds multiple cylinder's spark requirements causes the use of multi-spark to only happen at low engine speeds as there simply isn't enough time to discharge the coil, recharge and discharge it again and again in the time it takes the rotor to sweep a cylinder's discharge post of the cap. These systems use a transistor as an electronic switch to a capacitor, the capacitor shocks the coil with a much higher voltage having a sharp edged wave form than it sees from an ordinary 12 volts applied to the coil. This is a simplification of the circuit, but that's what's going on.

The OEM's have gone to distributorless systems with a coil for cylinder pairs or individual cylinders. This offers a lot more time to charge a coil for the next discharge but more importantly for them offers much better spark timing in general to the engine's specific in the moment needs and it allows advance management by individual cylinder, this improves power output, lowers emissions, and increases fuel ecomomy against the distributors one size fits all abilities.

So you have good parts in this engine to where you won't see any advantage in performance. The rev limiter of these msd features is nice if you bounce off red line frequently.

For my daily driver test bed of Frankenmouse I've been rebuilding the engine into Frugalmouse using Ebay lowest cost aluminum heads and intake eventually, I have the parts but not the health to put these on but that's coming. It curremtly is using a Speedmaster coil and distributor the model with the module in a doghouse on the outside of the body and their E core coil runs right up to my self imposed red line of 6200 without any issue. But does require a specific modification to the distributor gear if you use a GM Melodized gear as Speedmaster uses a larger retention pin than GM so the GM gear's pin hole has to be drilled larger, Speedmaster would have made life simpler for everbody if they used the aftermarket shaft size of .5 inch instead of GM's .491 inch. Yeah I run an Edie-AVS that I bought semi-new for 50 bucks from a guy at the parts store counter that screwed it up and wanted to return it and the seller wouldn't refund his money. Turned out it had a wet float, replaced the floats in the process of cleaning it and restoring it to proper configuration. Turned out the idle mixture screws a turn and a half, set the curb idle so about .020 inch of the transfer slot showed under the throttles. Put it on my engine, turned on the electric pump, gave it time to build pressure, cranked the engine it fired right up. The only problem it presented over the past year its been on is the accelerating pump rubber cup pulled over its stop and ceased functioning. Hunting through my fantastic washer colection I found a thin brass washer of perfect size, put it above the rubber plunger to trap it on its pusher shaft,,, problem solved.

Bogie

Been mentioned already, but I'll second it. A quality HEI distributor setup will work perfectly and serve you well. Several options out there on one, as they are popular and several companies have produced new units. No need to get a junkyard one, although if it's in good shape, it will work just as well......

So I don’t have a lot of room for and HEI. So I’ll be running and external coil. But what do you guys think about the ready to run e-curve? It seems pretty simple.

 

the multiple spark function is more of a gimmick, the capacitive discharge is what helps light a mixture in a high output application

 

FAST sells a box which is a clone of the Crane Fireball. Its probably better quality than what MSD is selling; the best boxes currently produced today seem to be from "Daytona Sensors". Me, Ive had the same old Crane box in several cars - if it ain't broke don't fit it.
One of my customers had an MSD box in their SCCA race car, the box died during a points race on the national tour, MSD told them they should just wire up 2 boxes in case one dies. Between that and the rusty distributors...Im not going to go out of my way to run an MSD product regardless of bragging rights

 

The nice things about the Daytona Sensors box are (I use it for 1-4):

1) Programmable timing curves including spark delay during starting for locked out distributors or crank triggers.
2) 2-step without popping and banging
3) Rev limiter
4) Data logging capability (logs my AFR and RPM among other things)
5) Boost timing retard for turbo apps
6) lots of other inputs and outputs.

As I understand it, the guy at Daytona Sensors came from Crane

 

Think about the multi discharge spark....... if the first one is per the timing setup, then each of the following discharges are retarded relative to the first. Possibly a span of 20 degrees behind the first spark to the last. Just logically it does not make sense to create several flame fronts over a span of 20 degrees. It would seem a single big spark is more effective working on the piston at one point in time at the optimum time.

On another note I’ve always used point ignition on street cars until recent. I made my own small diameter HEI distributor. And also use a modern weird shaped coil. The pick up, reluctor, module, and coil are standard auto parts pieces. Since redoing the points distributor to HEI I’ve noticed ease of start and the idle at the same advance and carb settings is about 100 RPM ‘s faster. Same everything else plugs and wires, just change from round coil to the modern “E“ type. I was able to idle it back and all else seems a bit (seat of the pants nothing scientific) smoother and stronger. This is just sharing my results of my HEI system.

 

You want a fat spark? Go find an old Delta Mark 10 or 10-B CDI box. Holy crap. Ive got one, you basically use the points as just a contact switch, they see very little voltage (which makes them last longer). But, good Lord can this thing light up your Christmas tree. I imagine if you could run that box, with a properly spec'd E-core coil (assuming you didn't want, or couldn't run, HEI) - it'd be a killer setup. Theres a small group of guys that keep these going especially in the aircooled Porsche community. In fact you used to be able to buy a kit to assemble your own. The schematics are out there, and most guys have crossed over the capacitors and diodes on the boards to current PN's.

 

my own race car still has a Firepower box built by a guy from Florida, the company that Crane bought when they wanted to get in the ignition business. Box has run at least 500 super late model races in 25 years, has never missed a spark that I know of.
I had a brand new MSD box in my first car. Car had practiced and been started in the shop, maybe 1 hour of run time. Went to a race in Mobile,AL, unloaded and the car would not start, no spark. Had to buy a box at the track. Lesson learned.

 

Interesting. I'm still running an MSD box made about 20 years ago. I had it checked by MSD about 15 years ago and no issues. I feel like most of the MSD issues stems from poor wiring jobs or weekly wash downs and vibrations. When it goes I'll replace it with another Jacobs unit like the other car. It's also never faulted either.

 

It can’t always be that, the guys on here gotta know what they are doing. My feeling is the current available boxes on the market are not of the same quality as the older stuff.

I’ve seen more guys at the cruise that remove or replace “boxes” because of intermittent functioning. My guess they are newer acquired just because the cars are fresh builds.

 

MSD built a bunch of boxes with screws holding down the transistors that were too long, causing them to not transfer heat sufficiently. This was in the middle 1990's. A local guy to me that designs and builds custom and prototype electronics was fixing them back then. He also used a mil-spec transistor instead of the one used by MSD which he thought to be not up to the task.
The running joke was that to run an MSD you needed 3, 1 in the car, 1 in the trailer and 1 back at MSD being repaired.

 

And my 1985 Mallory uni-lite with the original module continues to perform perfectly , LOL ����

 

Been mentioned already, but I'll second it. A quality HEI distributor setup will work perfectly and serve you well. Several options out there on one, as they are popular and several companies have produced new units. No need to get a junkyard one, although if it's in good shape, it will work just as well......

 

Yes, and the added function of variable dwell is a plus over just point or Hall effect sensor.

I’ve read not all modules are created equal. The GM Delco offerings are said to be of better quality. That’s not to say other aftermarket modules do just as well if not better.

 

I have used the standard electronic Chrysler without problems. If plugs, wires, the coil, and other parts are good you don't need the fancy stuff for a mild street engine.

 

I am a PerTronix loyalist. I have used PerTronix ignition systems for fifteen years with no problems.

I have a PerTronix Stock Look distributor in my 350 CI Chevrolet engine now with a stock AC Delco coil. The PerTronix ignitions will provide full coil saturation (dwell) time and will remain strong enough for a engine with up to 12:1 compression ratio from idle to 10,000 RPM or more!

A stock ACDelco 12v coil can provide up to 30,000 volts to the spark plugs if mechanical points are eliminated and the coil dwell time remains at 30 degrees throughout the RPM range.

 

Reading multiple forums , it would seem pertronix longevity is all over the spectrum ?????? ed. : as is everyone else's.

 

Davis Unified Ignition GM Tri-Power Distributors 14720BK

small cap, uses GM HEI module, mag pickup, includes matching coil

 

PerTronix modules received a bad reputation before PerTronix introduced their complete electronic distributors.

That was because the PerTronix modules were installed improperly in old stock GM worn out distributors. The point plate in the 1955-1970 stock GM distributors must have all the wobble taken out of the plate. That is done by installing the stock distributor in advise and spinning it by hand with or without a dial indicator so you can see how much wobble is in the point plate and how much thrust clearance there is in the distributor shaft. Even new old stock point type distributor have as much as .050” thrust clearance in the shaft and .025” ” run out or wobble in the point plate. The distributor shaft thrust clearance must be reduced with hardened thrust washers to no more or less than .015” . The point plate wobble must be reduced to .005” run out by tapping on the plate with a small hammer while turning the shaft after it is installed in a vise.

That excessive wobble in the point plate and excessive thrust in the shaft does not affect point type ignitions but can cause a PerTronix electronic module to fail. The PerTronix module cannot tolerate more than .005” run out in the point plate. Most part timers don’t want to go to that much trouble in order to install a electronic ignition control module.

That is why PerTronix introduced complete distributors that had been manufactured especially for their electronic modules.

 

I had two pertronix modules go bad as in poor timing repeatability. All distributor was tight no slop, clearance, or otherwise. The timing in engine perfect no chain slop. They just went bad. Replaced module with points and all is good as it should be.

I won’t Say pertronix is no good but I found it not to be reliable as the tried and true points. Maybe I had bad luck.

I have found the mopar type pick up module with a GM HEI module to be ok so far. The final judgement will be in with more time and use in my case.

Anything electronic is under the grace of God as to the life expectancy. It’s not like it gives much warning as to when it’s about to quit.

 

My advice is to install a PerTronix distributor instead of installing a PerTronix module in a stock point type distributor. Ten years ago, I took all the slop out of a 1963 Pontiac GM distributor and installed a PerTronix module. I sold the Pontiac three years ago and the PerTronjx module is still running fine.

I have a PerTronix Stock Look distributor and a NOS ACDelco coil in my 1962 Chevrolet with a 1968 350 CI engine and it is running great.

Point type distributors were eliminated by GM in 1972 and the chances of finding a new one or a acceptable used one is not very good.

 

But there is no real advantage to pertronix compared to points in my past experience.

Now an HEI system does enhance the dwell time and energy using an “E” type coil. The pick up head and GM HEI Module are pretty well proven technology and reliable.

Maybe pertronix has an improved product but I not going to give them another try with my funds.

 

With a points type ignition, as the engine RPM increases, the coil saturation (dwell) time decreases. If you check the point dwell at 4000 RPM with a point type ignition, you will find it is reduced to 25 degrees or less.


An engine equipped with a PerTronix ignition will maintain 30 degrees of dwell time from idle to the point when the engine destroys itself. If you install a PerTronix high capacity coil, the ignition output voltage will be even higher.

I use a stock ACDelco coil with my PerTronix “Stock Look” distributor because it “Looks Stock” . Even the stock ACDelco oil filled coil with a stock Ballast resistor and a PerTronix ignition, produces higher output voltage throughout the RPM range. A PerTronix coil would produce more out put voltage but you MUST eliminate the ballast resistance wire or resistor to use it with a PerTronix module or the module will fail. That is often overlooked and the module gets the blame for the failure.

 

Having a street engine a stock points or HEI distributor gets the job done. Both are dead reliable. HEI is variable dwell. Points does decrease as RPM goes up. Duel points helps that flaw. But how is this pertronix any better than a regular HEI be it a big or small diameter GM distributor? Tuff to beat the HEI. No ballast required and uses a “E” coil about $20 on line. Cost at swap meets for a good clean HEI distributor is dirt cheap and proven reliable. Best feature is parts are at all auto parts stores.

I just see the pertronix as nothing better than what I all ready have and it costs more. The previous pertronix designs (with my experience) do not have the same reputation as HEI or points units.

Not trying to be disagreeable but I don’t honestly see any benefit over the proven stuff for street use.