I've been running a Vertex Magneto on my small blocks in this 1968 Custom tilt nose Convertible Corvette since 1977. It has been great with the exception of being unsuccessful in having a tach work reliably. My question is what are other people running in their High Output small blocks?

 

Interesting ignition setup. Sounds like you are wanting to take a poll... if so - you can post a poll with a thread if interested.

(I don't have a high output motor so my igntion probably is not applicable to what you are looking for)

Good luck

 

How high of output/RPMs are we talking? I have no issues with my HEI.

 

I'm looking for Race quality 7K /RPM is where I should limit it; but I'm sure my Vertex will be fine to 12K/RPM and beyond. My Vertex needs to have the magnets recharged and the whole thing gone over, so I'm talking a few bucks. I'm looking for a back up plan. My small block has: solid roller cam and lifters, AFR heads,383 stroker, better than 500 HP & TQ.

 

Tach drive MSD requires ignition box Distributor

 

Tach drive D.U.I. hei is self-contained aka stand-alone

interesting tilt-nose styling

 

I have been running an all MSD ignition system on my 1968 L88 Clone and it works great. The MSD makes for a nasty sounding spark and lights off my fuel at 12.25-1 compression. The cylinder pressures measured on a compression tester shows over 245 pounds of pressure per cylinder.

Using good spark plug wires and fresh spark plugs the engine makes some serious horsepower. One thing I did learn was to use normal spark plug gaps or the ground electrodes could/would burn away quickly.

Other than no energy used in making the spark, what advantage is there to using magnetos on the street? My car came with a K66 Transistorized Ignition system. It was all rebuilt by Dave Fiedler and then stored away in vacuum packed bags in case some body wants the original system to put back on the car.

 

most mags (if in good condition) make a hotter, more energetic spark, than CD

FWIW top fuel dragsters run tremendous cylinder pressures. They can choose any ignition, AFAIK, they still run mags. Many are by MSD.

Mags are typically very reliable. Mags are de rigueur for many recip aircraft engines.

Some sixties & early seventies H-D Sportster motors (XLCH ?) were OE w/ Fairbanks-Morse mag

 

Thank You for the recommendation. I knew a drag racer in the late 70s who was going to jail for a crime he committed (I hadn't known of his criminality) .He sold me an $800 Mag for $50. It woke up my engine like you wouldn't believe. I send it to a Vertex Magneto Shop and have them go over it, changing advance curves recharging the magnets, new points, cap etc.. The work isn't cheap; but the Mag is awesome. I need to have them convert it to a tach drive. so more bucks.

 

Keep the Mag and change your tach over to electric. All the vendors sell the conversion kit.

 

I tried that and I had sketchy results, which is why I mentioned that I've been unsuccessful in having a tach work reliably. I've also been thinking about the feasibility of using an electronic fuel injection system which I understand works with the ignition system. I doubt EFI would interface with the Vertex.
You've stated that all the vendors sell the conversion kit. By Venders do you mean "Jegs" or "Summit" for example or "Auto Meter" or "Stewart Warner"?

 

Corvette vendors, Zip, Corvette Central, etc. why not the MSD tach drive distributor?

 

MelWff The question about the venders was meant for Crimson Thunder who stated "Keep the Mag and change your tach over to electric. All the vendors sell the conversion kit" I know who "Venders" are; but I asked for clarification from Crimson Thunder because I am familiar with gage MANUFACTURERS suppling conversion kits. If you read the other posts you would know the benefits of a Vertex Magneto. The post by Rebelyell gives an explanation of Magneto's virtues.

 

There are Not gauge manufacturers since you have the factory mechanical tachometer. Here is the conversion kit.
Conversion

 

Wasn't your original question what are people using? I gave you an example. Not many people are running magnetos. Good luck with your car

 

Nice save; but you weren't addressing the original question, you were answering a question which came from the thread not the post. Thanks anyway, perhaps you learned something valuable to a Hot Rodder, Magnetos are in a class all by themselves. Standard fair in aircraft engines. If you are not convinced I'll give you a lesson based on my aircraft experience. I was flight training using a Cessna which had 2 spark plugs per cylinder, each fired separately by a their own Vertex Magneto. As part of the preflight check each magneto is shut off individually while the engine is running to assure their function. When each magneto is shut off, the engine speed drops noticeably. This shows just how important a hot spark is to an engines efficiency and thus power output. This is why they are used on Top Fuel Dragsters. The main purpose of my question really had to do with EFI interface, which I believe would require some engineering to accomplish with a Magneto.

 

All the Corvette vendors. Corvette Central and Zip are my favorites.

 

I would respectfully disagree that the "hot spark" is the reason for the change in RPM when shutting off one of the two magnetos. When packaging two spark plugs per cylinder in a engine, their placement is usually inefficient (ie: placed opposite each other on the periphery of the bore, instead of the center of the bore). Things are fine when both plugs are firing (the two flame fronts only have to traverse half the bore diameter, similar to the distance from a center bore single plug), but when one of the magnetos is shut off, the single flame front has to traverse the full diameter of the bore, with this longer full combustion time ending up retarding the LPP point (the crank/piston location/position where peak cylinder pressure occurs), reducing the thermal/mechanical efficiency/power of the fuel burn. Switching the magneto back on gets the LPP point back closer to the ideal 15-20* ATDC.

I first ran into this interesting phenomenon as a young engineer while doing dyno work on a twin plug V6 prototype engine at my employer. As this was intended to be a passenger car engine (versus an aircraft engine) the additional (2X) cost for the ignition system/components couldn't eventually be justified. In an aircraft, if one magneto is lost, that second magneto is a bargain regardless of its initial cost.

 

OK I agree that an engine designed with two spark plug locations develop a flame spread that is limited when one plug is shut off. I acknowledge that the drop in engine speed may have more to do with an incomplete flame spread then the absence of the magneto suppling the spark. So the example I used was too simplistic and did not cover all the factors that caused the engine speed to drop. The older style Vertex that I have on my Corvette is still a $3000 distributer that supplies it's own electricity with alternating current (instead of direct current). My Vertex has been incredibly reliable.
My original question is what are other people running in their High Output small blocks? What is best to use HEI, DUI, Magneto?
Thank You for the input.

 

A casual glance at ignition systems over the years indicates that an energy delivery (to the plugs) of 75-125 milliJoules will satisfy most any engine requirement. The old points systems didn't deliver the same amount of energy that modern electronic systems do, but they still did a darn good job lighting off high compression mixtures despite lead-fouled plugs, and did that job up to 7k RPM in some production engines. A well maintained ignition system will work on most engines. For long plug life, a modern higher energy system is the way to go.

Don't get distracted by any coil "output voltage" advertisements. Those numbers only describe the coil internal winding insulation/dielectric. The actual voltage that a coil puts out is determined by the plug gap arc-over requirement. Once the arc starts, the coil stops trying to keep increasing that secondary voltage. What the coil does then is empty out the energy that was stored in the coil. The larger the energy storage, the longer the spark duration.

For specific brand recommendations, I'll leave that to the HP SBC guys to offer up their recommendations. (I'm running a mongrel ignition system in my BB. It's an HEI module controlling the stock can coil. Very reliable and plugs last forever. My engine CR is only 10:1, and I spend my time on road course events, so for reliability I don't rev my engine to the moon on the straights.)