Slow return to idle when engine is hot ,

[pud]

Hi, I have a small problem with my Porsche targa 2.4T 1970. When I first start to drive it and it's not very hot the revs are quick to return but as it gets hot they take a long time to come back down. Is it the distributor causing the problem , if I changed to electronic ignition would this solve the problem. Any help would be great, pud,

[steve911T]

Carbs or Fuel Injection? What year is the motor? 2.2 was only available in 1970. Could be the distributor, after all it is about 40 years old. Steve

[john walker's workshop]

tired distributor weight return springs are the usual culprit. good luck finding new ones.

[pud]

Hi Steve , sorry the car is a 1970 my mistake , would it be better to get another distrubutor , I think it's a merelli , thanks all , pud ,

[pud]

Also it has webber carbs , pud

[BK911]

Also check your throttle linkage.
I had a similar problem in a 72E.
When the car got warm the throttle linkage expanded a little bit and rubbed on something, causing the throttle to stick just a little bit.
This was many years ago and I forget exactly what it was rubbing on, but it drove me crazy trying to figure it out.

[pud]

Thanks for all your help , pud

[Grady Clay]

All good advice above.

Easy is touching the throttle rod between carbs while idling too high.
If the idle drops you know where to look.
Early 911s have an issue with the throttle link touching the edge of the tunnel behind the pedal.
Another potential issue is a failed accelerator cushion next to the transmission and subsequent mal-adjustment of the linkage.
Regardless of any linkage issues, this is a good opportunity to completely refurbish the linkage.

Yes, sticky weights in the distributor can be prime candidates.
You can easily see this with a timing light.
Again, this is a good excuse to rehab the distributor.

Another possibility is a temperature induced vacuum leak.
Use the classic ‘vacuum leak detection’ methods.
If you remove the carb manifolds from the heads, this is an opportunity to install the (’71T) phenolic insulators and longer studs (kit available from our host).

There can be other, more unique causes.
Was your fuel very low and high ambient temperature?
Evaporative emissions can be a culprit.
Take the gas cap off and see if the idle changes.

Where are you located? Unusual in Northern Hemisphere summer could be gasoline in your oil.
Remove the oil cap and see if the idle changes.

Best,
Grady

[pud]

Thanks Grady , will check all those things , pud ,