Since an MSD rpm chip is nothing more than a resistor in a fancy plastic case with two prongs, all you would need to know is the resistance value for each rpm level.

I just bought two adjustable chips. Not the Radio Shack type, ones already in a case. There are made by Shiftnoid (electric shifter company) and are sold by Jegs. they have a small screw in one end and adjust all the way from 0-12,000 rpm. Problem is that the screw has no scale on it. It comes set at 6000 and for every 1/4 turn of the screw it moves the rpm level by 100. Would be easy to get lost if you didn't know what the chip was set at. Also would be easy to lose count of the 1/4 turns if making a large adjustment.

I figured it would be easier and more accurate to set it by measuring the resistance. Borrowed a friend's chips and measured both his and mine. Used my digital multimeter set on the 20K ohm scale. Feel free to copy the list and I would appreciate it if anyone has any numbers to add. Would really appreciate those numbers below 4000. I use the lower chips in my MSD two step to control starting line rpm in my drag car.

RPM Resistance
3000 1.91
3400 2.21
4000 2.70
4600 3.21
5000 3.58
5200 3.77
5400 3.95
5600 4.16
5800 4.35
6000 4.57
6300 4.88
6500 5.10
6600 5.20
6700 5.32
6800 5.43
6900 5.55
7000 5.65
7400 6.12
7600 6.38
7800 6.63
8000 6.89
8600 7.69
8800 7.97
9000 8.27

It appears the scale is .10-.11 for every 100 rpm for most of the range, but is closer together below 4000 and wider apart at the top end of the range. Also may be some variance in the chips themselves. Example: I checked 3 different 6600 rpm chips . Resistance of 5.19, 5.20, 5.21.

Later,

I only have a 3000 and 5500-6500 chips for the auto-meter shift light. I'll measure their resistance if anyone is interested in auto-meter chips.

SteveW

The rpms are supposed to be the same. Would be interesting to compare what you have to the ones that I have already checked to see if they are the same.

Later,

They are pretty close;

3000 = 1.871 k ohms
5600 = 4.1 k ohms
5800 = 4.3 k "
6000 = 4.5 k "
6200 = 4.71 k "
6400 = 4.93 k "

Anyone else with any to add?

Later,

David Cole

Remember, I'm a bracket racer. I change nothing between rounds. I want each run to be identical to the run before. I am making the list so I can set the chips beforehand and do some test and tune with them. Once I get a complete list I'm going to print it out and then tape it inside the lid of my tool box. That way if I want a 4400 rpm leave I can set it before the first time run. Since I am starting from scatch with the Two Step I didn't want to go buy several packs of chips to find where I want to be. Once I find that spot it'll stay there.

Alex, you mentioned "old style triple zero chips". I assume you mean 6000, 7000, 8000, etc. What is the diff between old style and new style? Not that it maters I have the top limiter at 7600, shift light at 6800. The two step is new, so I'll have to play with what the car likes to leave at during a test n tune as soon as the weather breaks.

So much rain here I saw a frog wearing a life vest today.

Later,

Any of you guys use the "MSD Module Selector"? My brother has one - loves it - no goofing with chips.

About the only time we change a chip is if something is happening ie tires / traction go away.

Thanks Alex, I wasn't aware of a problem with the triple zero chips....I'll keep that in mind.

Butch

------------------
Alex Denysenko Co-Administrator and Moderator NHRA/IHRA/SRA member
Fleet of FoMoCo products
Moneymaker Bio
US Class Nationals link