Revving problem is solved!!

[Zedyone_kenobi]

Found my issue with a car that would not rev.. let me describe the symptoms, and maybe this solution will help others. My car no matter how smoothly or harshly I hit the throttle it would rev to about 4500-5500 and start to miss and sputter. Acceleration would stop entirely and the car would sputter around and the tach needle would oscillate up and down. Very disturbing. I thought it was timing at first so I adjusted that. I still may need to pull the distributor to see if the mechanical advance is gunked up. That was some good advice form a friend on these boards. I have not yet done that, but I did manage to find a spare distributor in my parts bin that came with my car. It was in used but very solid condition. Shaft was smooth and while it was gunked up in side, it had no shaft play, so this may be a good candidate for rebuild/cleaning.

But I digress. The spare distributor had a new cap and rotor on it. I have long suspected the rotor was an issue. It was only worn on the edge of one side. So I quickly put it on and swapped out caps. My new cap had the benefit of brass terminals, which is far better than the traditional aluminum.

Here is the rotor that came off the car.

You can see that one side is visibly more 'chewed up' than the other. In real life its far more pronounced, here is a better view,

Here is the rotor that went with it:

Once I installed these and hooked it back up, I was amazed at the difference it made. The car was smooth at 3k, 4k, 5k, and 6k. I did not rev it much past that and hold it, but it pulled once form 1st clean to 6500 rpm with NO fuss, mess or issues. I still think there is some timing work in there, but my gosh, it runs so smoothly.

I should have done this swap earlier. I installed a new vacuum advance, reset the timing, adjusted the valves, and all along it was the cap and rotor.

Guess it had reached the end of its serviceable life. If that gap grows too big, no amount of spark will get it to rev.

240ZED is a revving machine now.

[m4xwellmurd3r]

glad to see you found your problem. My problem is similar, but in my case it's caused by a lean condition (probably a crack in the boot or rotted vacuum lines)

[Zedyone_kenobi]

well, vacuum lines are next on my list of things to finish, I replaced half of them already.

I have a few more that need some attention.

[Poindexter]

I had a similar problem and it turned out to be inside the cap, the accumulation of brass powder/filings from the cap and/or the was rotor causing intermittent ignition. It limited me to around 5k rpm too. I fixed it, went for a ride and promptly my floor mat got caught in the gas pedal and the engine revved wild until I turned off the key- in like 3 seconds, but I had pegged the tach for those few seconds! Luckily the only damage was blowing a teeny tiny hole in the exhaust manifold gasket.

These Z's *certainly* can rev like a sono***un! Glad you fixed you problem so that now you can really enjoy that sweet silver beast.

[five&dime]

Think I am having the same problem in my 510. Just started doing this over the past few days. Picking up a new cap and rotor so I will update whether that fixed my Dat as well.

[Zedyone_kenobi]

Good luck Zero!

Thanks Poindexter!

[al_itzah2luv]

thats funny,

mine wont stop revving by itself...

like it wont stay a constant 1000 when idling...

[sblake01]

Doubtful that a new cap and rotor would fix yours..........

[al_itzah2luv]

no,

but i still need to get a new one of each,

lord knows whens the last time its been changed...

since theres carpet NAILED into my dashboard...

idk what this guy was thinking....

so a new dash and center console is added to my wish list of things to order this weekend.

[five&dime]

Curses!! Blast!!! Drat!!!!

Did NOT fix my problem

[HotrodPez]

Zero Z, I had a similar problem on my Z. Problem turned out to be a bad fuel pump. It was still flowing fuel when I pulled off the line to check, but I could hold back the flow with my little finger. No pressure! Replaced that and I was good.