So I’m going to start working on my Corvair here soon to try to have it drivable by the summer.
A guy I follow on Instagram that has been building Corvairs forever, started building one with a Seth Emerson HEI Stinger Ignition that’s designed specifically for Corvair engines, along with a Digital 6A MSD. I asked what the benefit was for the MSD, but in his typical fashion, he made some analogy that didn’t really answer my question.
What I do know is Seth with build the new ignition system specifically to run with an MSD box if you request it.
My engine is not stock. It’s punched out 0.60 over, has a 3/4 Race Cam (don’t ask, my dad installed it in the 70’s), Rhoads Lifters, headers, etc,
So what is the advantage of running an MSD box? I would like to purchase a Stinger Ignition and want to know if it’s worth the extra work to install an MSD.
I used them because I liked the rev limiter feature. Probably saved young me from blowing a few up. I beleive some of the nicer ones will do 2 step and pull timing for nitrous
Stands for multi spark discharge, so instead of firing one arc, fires many per trigger (In the very short specified amount of time) and achieves better ignition that way.
To be honest, hotter spark and a rev limiter.
Below about 2k rpm. Multiple sparks. So it maybe helps idle and low speed mpg.
My duster runs better with one.
My truck it made no difference.
Dallas mustang is made no difference.
The engine becomes far less sensitive to mixture as far as misfiring is concerned. As a consequence, it gets almost impossible to foul a spark plug.
Before I installed an MSD, I was replacing plugs every 3000 miles because they would be worn out. Afterwards, they would last at least 20k. I could also start the engine, set the choke, and walk away from it (preferably indoors) if it was around 0-10F, instead of having to sit in there and baby it to keep it balanced between flooding out, and not getting enough fuel. A stronger ignition system makes that range a lot wider. (That range can also be negative - I have had situations where it would starve for fuel and flood at the same time)
Downside: Cap and rotor life is very short. Drilling a couple 1/4" holes in the cap below the contacts will increase life greatly. I forget the mechanism, old racer told me about it. Before that I would have to clean the fuzz off of the terminals in the cap and the end of the rotor after every time I did any significant driving at high RPM. (Basically, on the side of the road after a rallycross when it would start stumbling/misfiring under light load) Brass terminals would probably also help but those don't exist for my engine anymore, just aluminum.
Definitely helps low speed performance on engines with radical camshafts, also starting, not just on Knurled's rotaries. The rev limiter is only OK, not magic, try not to bump it. I would use it in your application.
I remember the old “rhoads lifters tick because they work!” slogan
In reply to Patrick :
No mention about mushrooming the tops of the valves like an old chisel, or receding the exhaust seats 3/16" into the head because they effectively eliminate the closing ramp.
Some of the worst cylinder heads I've ever seen were bungled up due to those lifters. 3/16" may be on the low side, the valve faces were deep in the combustion chamber. Easily half of the valve lift was lost just getting the valve out of the well it was in. No wonder the engine "felt weak".
I assume Fiat gets away with not having an effective closing ramp on Multiair engines because they are only doing it on the intake valves, and the valvesprings are relatively light.
In reply to Knurled. :
My dad ran this engine hard in the 70s. As far as I can tell, they haven’t caused any damage to the motor.
That being said, this engine is either getting rebuilt or replaced with a turbo motor in the near future.
What they said. Primarily for the rev limiter. Not sure what cam that is, but if it is similar to something like an Isky 280, a rev limiter could be useful if you race it. I drove a Corvair with a 280 in it, and it really liked the upper rev range which required keeping an eye on the tach (it really wanted to shot past redline). BTW, if it is an Isky, be prepared for valve noise. I had an Isky 270 in mine for years and had noticeable valve noise (if you want to hear it, watch Mr Holands Opus, my car was used for the sounds of the sons car and I think you can hear the valve clatter).
I had an MSD for a while but never installed it, my cam is more of a mid-range torque cam so over revving is not a big danger. If you are looking for a good ignitions system, get ahold of Ray at AmericanPi, he has a good setup for a distributor less, coil pack style ignition (he also does FI). Ray can be a bit hard to get a hold of, but he is also probably the most knowledgeable Corvair turbo guy.
BTW- My suggestion for the fan belt is to run it loose, and spray with silicone to make it slip when you race it. I also suggest the Gates 3v560 belt (thin, so it fits low in the pulleys)
Another nice feature is super simple timing curves. Getting a mechanical timing curve (with vacuum to boot) exactly how you want it is a trial-and-error thing. Even then you're usually just getting close.
The Ford EDIS ignition system and many others use multiple sparks at low RPM (which is likely why it made no difference to the Mustang referenced above). I installed an EDIS solution on my 924 to replace the stock distributor and "Bosch electronic ignition" and controlled it via MegaSquirt. Worked quite well and provided much more finite control over the ignition curve.
Generally many of the features of the MSD system are available elsewhere on other solutions, but it is packaged and supported quite well. For carbureted engines, its a decent solution. Certainly better than much of what was available on the vehicles at the time. For a modern engine? I'd skip it and use the built-in ignition and fuel injection system (or an aftermarket solution to manage it, like MegaSquirt, etc.)
If you want to provide your own ignition curve, then I'd look at something like MegaJolt Jr. over the MSD. If you're going to use the stock distributor and a set of carbs, then toss an ignition box of your preference at it and enjoy a slight upgrade at idle over stock.
Might Suddenly Die box? No thanks. Ever since the move to Mexico.... I’d pass.
In reply to Stefan :
Depending on the spark plugs you are using, the shorter, higher intensity capacitive-discharge spark is more beneficial.
There was a thread I'm not even going to try to find about ten years ago on rx7club that went around and around with people saying regular ignition is better and MSD is a waste, no MSD is godlike and inductive ignition sucks, etc. Then, somewhere along the way, we started to realize that the people who liked MSD were using one type of spark plug, and the people who weren't were using another type.
Interestingly enough, the Mazda sport preparation manuals are somewhat available online, and they changed the type of spark plugs they recommended after they switched the racing vehicles over to a capacitive discharge ignition. Not multistrike like MSD though. With the old ignition systems, they said you had to warm up the engine on the stock NGK heat range 7 plugs and then switch out to 10s for racing. With the capacitive ignitions, they didn't say anything about different plugs for warmup, but 10s were the hottest plugs recommended and in some cases they called out 11.5 or even 13 heat range plugs! (At which point the plug gap has to be in the .010" range to keep it from flashing over to the shell)
Ranger50 said:
Might Suddenly Die box? No thanks. Ever since the move to Mexico.... I’d pass.
So is there a similar product with better quality that you suggest?
