Pertronix installation, a couple issues after done 240z

[71Nissan240Z]

I just installed the pertronix ingnition kit and blaster coil 3ohm. I didnt remove the distributor off the engine so the timing is the same. The car ran fine before, carbs were tuned, cap rotor, wires, plugs all good.

The car seems to start up real well and idle good. Seems to have more power.

Two issues tho.

The tac now seems to drop at around 3k to zero and back up when im giving it alot of gas

The car had a backfire through one of the carbs at 4krpm or so.

I didnt have any of these issues before the installation, Im just wondering if someone can point me into the right direction to see what I can do.

Thanks!

[Arne]

First thing - check the timing. Doesn't matter that the dizzy wasn't moved, the Pertronix sensor will not be exactly the same location as the points were before you removed them. In my car, the difference when switching between points and Pertronix is at least 10 degrees.

[71Nissan240Z]

what should a good timing degree be? How do I check the timing? below 900 rpms and with the vaccum advance off?

I have the 3ohm coil but i have the system still running through the ballast resitor, should i bypass the resistor and connect the two wires together?

im researching this extensively on here and other forums as we speak.

[Arne]

Timing should be whatever worked before you did the conversion. It may be different than stock depending on your car, conditions and config. Stock is 5 degrees BTDC. I'm running about 10 degrees on mine.

With the 3Ω coil you should bypass the resistor.

[71Nissan240Z]

I suppose thats the reason why I had a backfire at 4k. Ill have to bypass the resistor.

The instructions said to leave it in place, I was kind of suspicious to this, but ill go ahead and bypass the resister by securing the two wires together.

As far as timing goes. My car has a f54 block, p79 head, mild cam. 180-190psi each cylinder. Stock header, straight exhaust with turbo muffler. I didnt check the timing prior to installation, so I may have to play around. Supposedly my compression ratio is around 9:8:1, I run premium fuel...should I slowly retard the timing first? or advance?

My other question is, the tac bounces at 3 k when I get it a lot of gas...if I wind it up slowly it doesnt do it. It could actually be related to still being connected to the ballast resistor. I have to wait to try the car again...any input on the tac issue?

thanks for all your help!

[Arne]

Don't worry about the tach until you get the ballast and timing taken care of.

Timing - if you don't know where it was, I'd start at the stock setting (5° BTDC). If there is no ping during a good test drive, advance it a few degrees and re-test. If the cam you have is stock, I'd say 8-10° as a guess. If it is a slightly hotter aftermarket cam, maybe 12-15°. But those are just guesses - every motor is different.

Resistor - The goal with the resistor is to get close to 3Ω total. The stock coils are about 1.6Ω, so they use a 1.5Ω resistor in the circuit. If you had bought the 1.5Ω Pertronix coil, the resistor would still be needed to get to the desired 3Ω total. But since you got the 3Ω coil, you don't need a resistor.

[71Nissan240Z]

well when I bypassed the resistor the car no longer backfires and pulls really hard. Problem is, I dont know where my redline is. I can go by feel, but id rather know what rpm range im at. I imagine i shifted around 5k but the car has plenty more after that so I need to take care of this tac issue.

Someone mentioned putting a 1watt 35,000ohm resistor between the tac and positive wire feed.

[Zforce]

I don't see how a resistor would work since all the power to the ignition runs through the tach. Exactly how did you wire up the Pertronix ? The red wire from the pertronix should get the full 12 volts from the black wire with the black plastic sheath, since you got the 3 ohm coil bundle all three wires, 12v ignition, red wire from pertronix and the green current sensing wire from the tach, the other black wire goes to coil positve and the black wire from pertronix to the negative. Another test would to put the stock coil back with the ballast resistor, if the problem goes away I would get the 1.5 ohm coil and run it just like stock, thats how I run mine and never had a problem.One other thing you might try is running an extra ground wire from the distributor to the engine block and retain the ground wire inside the distributor.

[Arne]

OK, one down. As for the tach, did it work OK before the Pertronix? Because the tach in my '71 doesn't seem to care whether the resistor is connected or not. Works fine either way.

[71Nissan240Z]

I first installed the blaster coil with the stock points. I even had it feeding through the ballast resistor. The tach worked fine with that set up and when it was all stock.

When I installed the ignitor set up, I initially had the red wire from the pertronix kit going to the unresisted side of the BR. And had the black wire from the pertronix kit to the - on the coil. Everything else was stock and where it should be. Went for a drive, the tach went crazy and the car backfired through the carb at 4k, which it never did before.

So I saw that the instructions I used were for a 1.5ohm coil which retains the BR. I had the 3.0ohm coil, so I took the red wire from the pertronix kit off the BR wire and connected it to the + side to the coil. I then took the BR out of the loop by just connecting both wires to one side of the resistor to take it out of the circuit.

So basically I have the black wire going to the - on the coil

The red wire going to the + on the coil

And I have the BR bypassed by connecting the two wires at one side of the resistor to take it out of the circuit.

All the other wires are at their stock locations on the coil.

The car now runs great, and pulls hard...so I know the BR was not needed with my coil. The tach will kinda work if im giving part throttle but as soon as i stomp on it...it drops to 0 until I shift or let off the gas.

I heard that a tach adapter that is used for the MSD ignition will work? Id rather know for sure before I go through the trouble of soldering everything and taking my tach apart though.

Here is a picture of my set up at the coil. I took the coil wire off to be able to show more wires.

Edited May 24, 2011 by 71Nissan240Z

[Travel'n Man]

Have you tried removing the BR and totally bypassing...........might be worth a try. I physically removed my BR and have no issues at all.

[71Nissan240Z]

Have you tried removing the BR and totally bypassing...........might be worth a try. I physically removed my BR and have no issues at all.

No I have not tried that yet, I don't see why it should need to be removed since it's already removed from the circuit but anything it worth a try. I believe the 72 tach is different inside than the 71? My build date is 6/71.

Do you have your pertronix wired the same way as mine besides the resistor? I was thinking of also removing my pertronix red wire from the coil and moving it to where the two wires connect at the old BR.

After finding so many numerous threads and no fixes to this issue, Im going to try my best to find a solution and share it with everyone.

Edited May 24, 2011 by 71Nissan240Z