Rev Limiter Troubles

[mhibbs]

I just put a Pertronix rev limiter on my new Merlyn. I'm 100% sure it's hooked up correctly, I've got 2.5volts and a correct tach reading off the tach lead. I set it to 3000 and rev it up in the garage and I get some erratic tach behavior beyond the rev limit setting, but it's not really dropping the cylinders like I would expect and continues to rev fairly clean (clean enough that if it did the same thing at 7000 it would be bad news). I can't take it out for a spin and see if it changes under load b/c the car is too low to go cruising around my neighborhood. Does this sound normal to anyone? This is my first experience w/ a rev limiter on a points ignition but it's too damn simple to be this hard. My Caterham race car has a full electronic MSD setup and behaves more as expected.

Have I lost my mind? Thanks guys.


Mitch

Edit...I've given this some practical thought for a while and think I may not have a solid enough ground.

[mhibbs]

Ground wasn't strong enough...should have just quit screwing with it and had a couple of beers...like most things.

[Brian]

The next time you get an intermittent misfire, just disconnect the rev limiter as the first thing you try - should shorten your troubleshooting... I put them on two cars, now I just make sure the shifter works properly and don't miss shifts...

Brian

[mhibbs]

Actually, the rev limiter wasn't *causing* problems, it just wasn't working properly due to the insufficient ground. Disconnecting it of course worked fine, I was trying to get it to work. It was all for not though, b/c after working great for the first day of practice, it crapped out in the first race and started coming on at 5800! I took it off for the rest of the race weekend. It WAS a brand new rev limiter...I think vibration killed it.

[racer27]

My Pertronx rev limiter also died after one event... If you take it apart, you may find the broken lead or loose screw. It definatly was not built to withstand the enviornment these things have to operate in for us.

I fixed mine and then put some RTV over the connections to keep it secure. I then sealed it with Silicone and wrapped it wiht hear shielding foil. After repair, it worked fine in the garage. However, I never track tested it. I replaced it with the MicroDynamics Rev-Limiter, after 12 races, no issues at all.

[mhibbs]

The odd thing about mine, is it still works as expected at lower RPM settings...say 3500 for example. If I turn it back up to 6800 where I had it set, the ignition breaks up around 5800-5900. The MicroDynamics unit would be fine...I'd just rather have something you can set to a value rather than doubling the engine RPM. I would have gone w/ the MSD unit from the beginning but the size of the Pertronix was appealing. I'm going to attempt to get it replaced under warranty and I guess try rubber mounting it.

[PCalhoun]

I have fried two Pertronix RPM units and talked to them at PRI. Two things were noted:

1. Good Ground- preferably to the battery

2. Flat Surface Mounting- Do NOT mount on rubber bushings to control vibration. The back of the unit has a cooling vent hole, which when mounted to a flat surface helps keep the unit temps down.

Will this work, we'll find out in the spring, but I have Pertornix Tech contacts if you need them. I have found them to be very helpful and they stood behind their product.


Peter Calhoun
Pace American, Inc.

[mhibbs]

Yes, please send me the tech contacts.

[PCalhoun]

Here it is Pertronix Tech Help-

Marvin Grebow Jr.
marving at pertronix.com
T 909.599.5955 x1030


Peter Calhoun- Marketing Manager
Pace American, Inc.