260Z - over revving on gear change

[bobzilla7]

My car rev hangs when changing gear (sometimes going up slightly before dropping back down), but the revs drop off immediately when stationary on the driveway. Any idea what could be causing this? The linkages all seem to be working perfectly.

 

[MCBladeRun]

You running carbs or something else there bobzilla?

 

[bobzilla7]

Apologies... carbs.

 

[bobzilla7]

Apologies... carbs.

 

[MCBladeRun]

Ah round tops, cool.

When was the last time you changed the oil in the dampers?

 

[bobzilla7]

The engine has just been striped and rebuilt. Maybe 300 miles. I topped up the dash pots today and went for a short drive. Same issue. Maybe, just maybe, slightly less.

 

[MCBladeRun]

The engine has just been striped and rebuilt. Maybe 300 miles. I topped up the dash pots today and went for a short drive. Same issue. Maybe, just maybe, slightly less.

Hmm, rebuilt engine? Did you readjust the settings on the carbs? They'd need a new set up if that engine is running better. Only other thing is the vacuum advance on the dizzy?

 

[toopy]

I had a similar thing quite a few years ago now, when driving the revs would regularly stay slightly elevated at idle when stopped in traffic. If i blipped the throttle it often cleared it, the throttle linkage operation seemed fine to me but i dismantled it all anyway, cleaned, repainted and greased where necessary and it has been fine ever since!

 

[toopy]

It may also be the carbs are slightly out of balance, an airflow meter is your friend in that respect.

Also check the vacuum hose between brake booster and inlet manifold.

 

[bobzilla7]

Right, thanks guys. A tune up was on my list of things to do.

The vacuum hose is new, but I will double check.

 

[MCBladeRun]

Right, thanks guys. A tune up was on my list of things to do.

The vacuum hose is new, but I will double check.

Good luck, let us know how it goes

 

[Rob Gaskin]

I would make sure the linkage is free and works well over the full movement. I've had a situation where it can go too far (over centre). I suggest that you use more throttle when driving than when it's got no load (stationary). Is the return spring good? Carpet/soundproofing clear?

 

[Robotsan]

I would make sure the linkage is free and works well over the full movement. I've had a situation where it can go too far (over centre). I suggest that you use more throttle when driving than when it's got no load (stationary). Is the return spring good? Carpet/soundproofing clear?

I had the same thing with my 280z - turned out to be the return spring. It fell apart in my fingers when I eventually removed it.

 

[bobzilla7]

Good luck, let us know how it goes

Will do!

 

[bobzilla7]

I had the same thing with my 280z - turned out to be the return spring. It fell apart in my fingers when I eventually removed it.

New springs. The only one I haven't checked yet is the spring on the pedal.