Switched to Valvoline VR, now low RPM

[zorin]

I have a '79 911 SC 3.0 L engine and solex carburetor. Last year I replaced the flywheel with Fidanza (Aluminum) and used a lightweight Pressure Plate. Last summer I used Castrol syntec 5W50 on my car. When I took the car out this spring the car had started to smoke. I just changed the oil and used Valvoline VR 20W50 instead. Now I have noticed a drop in idle speed (the second mark) and hence stalling when stopping at traffic lights, even when the engine hot. Also, the engine hesitates below 4000rpm. There is still a bit of blue smoke sometime in accelartion and start up.

Should I use a thiner oil or just increase the idle speed? What is the normal idle speed? I am hoping the smoking will go away as I drive more. I followed the proper oil level checking and fill up (used 12 quarts).

Thanks.

[DRACO A5OG]

Is the oil fill cap on tight or seal on the cap in good condition? Sounds like you have a vacumm leak

[sailchef]

Did you recheck oil level when car was warm and on level ground?

When you change the oil there will be a quart or more left in the oil lines & front oil cooler, and, a little in the crankcase unless you drained the sump.

haveing said that, if you added another 12 quarts there may be to much oil in the motor, hence the smoking on accelleration.

[Aurel]

I switched from Castrol 10w30 to Kendall GT1 20w50, and I noticed my idle dropped from 950 to 800 rpm. It must just be the thicker oil causing more friction, and I readjusted my idle speed. I did not notice any effect at higher rpms though, except the motor is a bit quieter. Normal idle speed should be 900-950 rpms.

[zorin]

Thanks.
I re-checked the oil on level ground , while idling, after driving for about 30 minutes. It was about quarter of an inch below the max mark.
If there is too much oil, should I just drive it until smokin stops?
What about the cause of low idle and hestitation in accelartion before I hit 4000RPM? Is this normal behaviour for 20W50 oil weight?

[moneymanager]

My car smokes when the oil is that high; stay half way between the lines and you'll be happier I think.

[zorin]

Plug wire for cylinder number one was loose so there was no spark on the plug, hence:

[JFairman]

That plug was firing till it completly loaded up with burnt oil carbon.
There may still be an occasional small spark arcing around that carbonized blob.