by Jim Cox
Since we all love our Jensen Healeys and would never get rid of them, we have to look for ways to improve upon the deficiencies left over by the factory. Luckily, we have "Father Time" on our side. Technology has marched on giving many improvements in the areas of sealants, gaskets, lubricants, coolants, bearings, fuel pumps and water pumps. One of the parts that has not improved over the years is the ignition distributor. I remember when I first bought my Jensen and did a tune-up. I knew there had to be a better way.
Let's take a quick overview of "How the Distributor Turns". The crankshaft pulley turns a toothed belt (that stretches), which turns the oil pump pulley (that has a oversized slot), where the distributor shaft fits (not a perfect fit either). Even the distributor new had variable amounts of play. I remember reading an article in one of the club newsletters about someone putting a brand new Lucas distributor on a Distributor Test Machine. The outcome, a considerable amount of variance in the timing of the opening and closing of the points.
Not knowing what I was up against, I went down the following path, so sit back and enjoy the story. I had side draft Weber carbs (45 DCOE) and a stock ignition system. The car always ran rich, got bad mileage, and expelled lots of black smoke during mild to heavy acceleration. Oh yeah, let's not forget about hard starting because the plugs were always fouled.
STEPS OF CHANGE:
1) Changed plugs to hotter range, temporary improvement.
2) Installed high output coil, again some improvement (I think noticeable only because it had gotten so bad), approx. $70.
3) Installed an Allison Ignition system, it replaces the points with an LED and infrared detector. Probably a 10-15% improvement in all around drivability and starting. If left for long periods of time it would start harder that what I thought it should. And of course it still relied on the accuracy of the mechanical drive system. Approximately $130.
4) Switched to an MSD Ignition system and high performance wires. This system provides 4 short multiple sparks of higher energy to fire each plug. This uses the distributor and stock points for the trigger mechanism. THIS was a major improvement in performance and drivability! Now, there was hardly any fouling of plugs and only some black smoke under heavy. acceleration. If you want to do something with your ignition system, this is the minimum system change I would recommend. There are plenty of people using this setup in Jensens. It provides in the range of 30-40% improvement over the Allison system and cost around $250.
Let me take a break at this point and say that the above happened over the course of 5-6 years, and in between changing the systems I tried every type of plug, plug wire, caps and rotors, rebuilt/rejetted the cards, and installed a high performance fuel pressure regulator.
THE FINAL STRAW: One day I went to start the car, it had been sitting for a couple of weeks. It started, but was running rough. I thought it was just cold! After 10 minutes I decided something was wrong. I checked the obvious and then pulled off the distributor cap. A nice puddle of oil soon formed below the distributor opening. Thin film of oil on electrical parts is not very conducive to smooth running. Time to spray down the inside, "BRAKE KLEEN" works well. This was the third distributor installed over the years, and they all leaked oil into the points area.
5) In 1986, a company called Electromotive Inc. came to our rescue. They developed the "HPV-1", a Distributor less Ignition System (DIS). As the name implies you remove and throw away (or sell to non-friends) the distributor. The HPV-I comes with a 60 tooth sprocket, a magnetic pickup, and a black box with wiring harness. What makes this so good?
(A) When the sprocket mounts on the crankshaft, you have eliminated all of the mechanical play inherent in the original design
(B) The HPV-1 is also known as a "waste spark" system, since it fires two cylinders at the same time. One cylinder is on the Exhaust stroke and the other is on the compression stroke where plugs normally fired.
(C) There are three ranges for adjusting the timing advance curve, 0-1000 rpm, 1000-3000 rpm, and 3000-8000 rpm.
(4) There is a built in Rev Limiter, adjustable from 0 - 8000 rpm.
This keeps the plugs much cleaner and less prone to fouling at idle or low power use around town. It also produces a longer duration, higher energy spark than other types of systems, which means more power. The ³waste spark² sounds good/impressive, but I was skeptical of what it would provide in real use. Well, it makes the engine run smoother at idle, and under any kind of acceleration, I have no more black smoke for the cops to follow. In the seat of pants testing using a stopwatch, the performance was considerably better in every range. I would say the difference was like adding together all previous changes and then some. The system cost between $500-$600 for the complete installation, depending on the machine shop. There are 3 items that need to be addressed for the installation.
1) You need to plug the hole where the distributor shaft goes into the back of the oil pump.
2) A bracket must be made that will hold the magnetic pickup tight, and at the proper distance from the sprocket teeth.
3) To Install the sprocket - donıt follow their directions. Instead, take your existing pulley off the crankshaft and to a machine shop. Have them mount it in a lathe and precisely machine the recessed area where the bolt and washer fit. Next machine a piece of round aluminum stock to fit into the recessed area. It should be a tight fit! The length of the stock should stick out past the face of the pulley by approx. 1/8". Now the outer 1/16" needs to be machined down to the exact size of the opening in the center of the sprocket (approx. 1"). Drill a hole through the center of your new adapter for the bolt to hold the sprocket, adapter, and original pulley onto the crankshaft. If you have done everything correctly the original washer will be concave enough to press the sprocket against the adapter against the pulley to the crankshaft. You will need to replace the original bolt for one that is 1/2" to 3/4" longer, and it should be case hardened steel. NOW that you too have found JH ignition NIRVANA, where can you get one?
ps. I have had my system now for over 3 years and havenıt had to touch it, except to show people how easy it is to set and adjust.
I would also like to add a note of recognition for the machine shop assistance I received from Richard Reyman at West Coast Racing Head Services.