Rev limiting problem at ~4000 rpm

[madkaw]

Here's my 2 cents! You need to proper impedence coil for your pertronix. So as said earlier, certains coils require the ballast resistor and some don't. When I did mine I opted for a coil that eliminated the ballast. I also had a rev limiting problem, but it turned out to be the carb floats improperly adjusted. Your mechanical advance unit will also cause the same issue. Pull your dizzy out and get to the mechanical advance and make sure it moves freely and the springs are working.

[motorman7]

I know Arne had some difficulty with the ZX dizzy, but it worked like gold for me. I was running the Petronix and couldn't get the motor to run well over 4K. Put in a ZX dizzy that I got from the Pick-a-part for $40 and it'll now rev till she blows- I've hit 7-8K revs with no problems. I am running 6 into 1 MSA headers, SM needles in my SU's, and stock mechanical fuel pump.

Rich

[VaGuS510]

Plug wire changed nothing... I will attack the coil next, I am thinking of just buying a performance coil of some sort. Any recommendations?

First, I will clean up my coil connections. And it sounds like I shouldn't eliminate the resistor??? (unless I get another coil???)

And my distributor is a vacuum advance... is there a way to test if its is working well?

By the way, when I swapped out my wires I check plugs and gaps. The rear three plugs where rather white. There was some oil around the washers but this may have come from elsewhere.

Thanks everybody for you responses. I will keep you posted with my progress

[Oiluj]

FWIW, I run the Pertronix and she revs just fine. I agree with others that it sounds like an ignition problem. Also check that your fuel filter isn't clogged.

[Arne]

First, I will clean up my coil connections. And it sounds like I shouldn't eliminate the resistor??? (unless I get another coil???)

You can bypass it temporarily for testing, but you are correct, don't eliminate it unless you change to a different (3.0 Ω) coil.

If your car is suffering from the same issue as mine, I suspect that by-passing the resistor will either eliminate the issue, or at least raise the RPM ceiling noticeably. If it doesn't change things, I'll shut up, as my experience will no longer be relevant.

[VaGuS510]

It looks like old blue is going to have to retire soon. I bypassed the ballast resistor and it did allow me to rev all the way to 5500 rpm before it began to hiccup. At partial throttle it seemed to have more power from 3500 up.

My brother might have a spare performance coil lying around. If he doesn't, what brands would you suggest?

[Marty Rogan]

Check the Pertronix. The magnets fell out of mine and it ran like crap. I have had 2 of them fail, so I switched to the 280ZX dizzy and had no more problems. I used an MSD Flamethrower coil, with good results.

Marty

[VaGuS510]

I have a Pertronix coil on the way. It was the only 3 ohm performance coil I could find. I will let everyone know if this fixes it.

It looks like my magnets are still there, so that is good.

Thanks everyone for all of the help.

[mayitin]

The old blue coil is not the original coil is made by Bosch. Years ago Bosch made the blue and the red the red was like a super coil. I have the MSD Blaster coil for about 15 years never had a problem with it, I also have the Alison electric Ignition for about 20 years never had a problem with it. ( now I think is made by Crane ) I have not check my timing since then. I like Petronix is very simple but I have never use it. My car revs with not problem. If the back plugs where white, your are lean.

[Arne]

While my original coil is black with red screen-printed writing, I believe that some of the original 240Z coils were blue in color. Not the same as the Bosch Blue.

Edited April 28, 2011 by Arne

[mayitin]

I would not be surprised, I just never seen one light blue, usually they are black or rusty color hahaha. One way to find out, and I may be mistaken, is to look at the top of the coil it will read Bosch.

[Jetaway]

An immodest question:

Are you sure your tachometer is right?

Assuming a stock 4-spd w/ stock rear-end and tires close to the size of the originals, you should be able to get into the 60s in second. Road and Track has the 1970 going 63 mph at 6500.

Could be the vacuum advance, though I have my doubts. Easy enough to check, though. Disconnect it, plug the line, advance the timing 3-5 degrees or so to compensate (keep the window down and listen for pre-ignition) and give her a test run. If it runs out to 6500 / 7000 you've found the problem.

Chris