Mopar Distributors
Mopar distributors have some inherent design problems that although are challenging can be overcome with the right equipment and knowledge.
The biggest problem is in the advance plate itself, if you disassemble the distributor you'll see how it just sort of floats in a slot. As the vacuum advance unit moves the plate is doesn't stay flat and true, it lifts up and down causing fluctuations in the timing and an engine that just doesn't run consistent.
We have found the best way to cure the inherent problems with these units is:
1. Weld the advance plate solid.
2. We weld in our adjuster tubes and using the set screws limit the total mechanical timing to the appropriate number of degrees to keep your total advance to what ever the correct number is from our experience for your application.
3. Once this done we can then take the distributor to the Sun Machine and start to adjust the timing events to suit the application by carb type, vehicle weight, cam and gearing from the convertor to the tire diameter. At the same time for a nominal charge we can run your box, coil, wires, cap and rotor and let you know all the numbers on your box and coil output up to 8800 RPM or to their fail point. We also test each plug wire for acceptable resistance levels and give you a complete report on your system.
Because we like to use only mechanical advance (Stage 2) for performance applications we can set the timing events by engine RPM and bring each event in at a specific RPM for launch, shift points and reduce the chance of detonation by limiting the total advance and at what RPM this occurs.
These numbers come from about 40 years of tuning on dirt tracks, drag strips and on heated up street cars, these numbers are not pulled out of thin air they come off a spread sheet that records the success's AND failures of all testing done over the past 12 years and probably over 5000 distributors including Ford and Chevrolet.
One other thing we have found in all this R&D that unless your running a dome piston (Greater distance for the flame front to travel) or your motor has been stroked, 34 degrees in a Mopar is about all they need. The plug position in a Mopar Iron head is probably the best of the big 3, it's very close to center (as in Hemi) this characteristic gives the flame front a shorter distance to travel by allowing it to travel nearly 360* from ignition point thereby achieving the maximum expansion point quicker. Timing numbers much higher than 34 are not necessary to achieve complete combustion at the correct piston position 12-15 ATDC and therefore the most power. Remember the optimum pressure on the crank needs to occur at about 70* ATDC
If your running 14:1, aluminum heads, C17 fuel, dome pistons and whizzing the thing to 8,000 RPM you may need more total advance, we can also calculate timing events on these engines.
The bottom line is, if we do our performance curve, phase and rebuild on your distributor they perform flawlessly up to 8000 RPM and for $125.00 you won't find a cheaper or easier HP and drivability bolt-on anywhere. Not to mention the ease of mind you'll have in knowing that there's no detonation going on that your not hearing over the roar of open headers, loud street exhaust or your favorite Tex Ridder 8 track tape.
This is just a quick review of the information available for your ignition system in our 38 page Tuning Guide available Via Email for $10.00. Hard copies should be available in February of 2006 for $20.00.
Click here to learn more about our book.
Of course you can use the spring kit and keep the vacuum unit and do allot of guesswork or have a Buddy sit on the fender with the dial back timing light as you run it down the road at WOT...Yikes...hang on ...NOT RECOMMENDED
We can do your distributor or we have cores here we can build to your specific application for an additional core charge, refundable on receipt of your core.
Some mild performance and stock motors will run better with a vacuum advance unit, give us your specs and let us make that decision.
Mopar Performance Distributors
These distributors are not ready to run out of the box. They have an extremely light set of springs that will bring your timing in at about 1600 RPM and unless you have a 4000 stall convertor and 4.10 or better gear set in a 2600# car your timing is way to early and will cause detonation.
They are a pretty decent distributor and with the proper curve and phasing they work pretty good and can be used for most applications from an almost stock to 11 second bracket car after they are set up properly.
NOTE:
You can not run a magnetic pick-up electronic distributor with a points style voltage regulator, you must convert to either the new style electronic regulator or use one of our Resto Voltage Regulators.
http://www.4secondsflat.com/regulator_tech.html2 Pin/4 Pin Ballast Resistor
Unbolt the old ballast resister and install the new ballast resistor in it�s place.
Note: The ballast resistors used from 1972 through 1979 had four terminals. The new performance resistor has only two terminals. The two extra terminals fed the fifth pin used on the early ECU; and are not required with the performance four pin ECU.
On the first connector of the new ballast resistor, plug the terminal containing the 14-gauge brown wire onto one terminal of the new ballast resistor. On the second connector, plug the terminal containing the 16-gauge dark blue wire onto the other terminal of the new ballast resistor. The unused terminal on each connector will be left empty. As stated in step #5, they fed the fifth pin on the ECU and are not required on the new four pin ECU.
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