Lumpy Running

[V8 Animal]

Sorry another lumpy running thread.
After having a service it was reccomended that i replace the vacumme advance unit as it was seized some of you might recall a earlier post.
After fitting the unit the idle speed was sticking.
Advance the dizzy a bit which stopped the sticking revs but the engine is hunting.
Quiet noticable today after a run to a tvrcc meeting difficult to maintaine a smooth ride at 2.5 thousand revs.
I have also replaced the leads with magnacours and the dizzy cap and rotor.
On the drive home decided to pull of the vacuume pipe of the plenum and ran remarkeably well but not perfect.
I will replace the ignition coil with a bosch one and a fuel filter this week.
Any thoughts?
V8 Animal

[GreenV8S]

If you disconnect the vacuum line you need to plug the port at the plenum end otherwise the air leak there will cause trouble. If advancing the vacuum advance fixed an idle problem, it may be the base idle was set wrong and the stepper motor was running out of travel and sticking. I'd suggest starting from scratch, disconnect vac advance (and plug the throttle end), set the ignition timing about right (I'd guess 10-12 deg advance would be about right), set the base idle, get it warmed up and idling steadily, disconnect the stepper motor, see if the idle behaves itself now.

If you do all that and you still have an erratic idle then something is wrong.

[V8 Animal]

GreenV8S said:

If you disconnect the vacuum line you need to plug the port at the plenum end otherwise the air leak there will cause trouble. If advancing the vacuum advance fixed an idle problem, it may be the base idle was set wrong and the stepper motor was running out of travel and sticking. I'd suggest starting from scratch, disconnect vac advance (and plug the throttle end), set the ignition timing about right (I'd guess 10-12 deg advance would be about right), set the base idle, get it warmed up and idling steadily, disconnect the stepper motor, see if the idle behaves itself now.

If you do all that and you still have an erratic idle then something is wrong.

Thanks for the advice,
I did mark the base of the dizzy before moving it whereabouts do you you get the 10/12 marking point from?Throttle end i asumme means on top of plenum chamber and the stepper is clean.Is the idle screw on the top of the plenum a small allen bolt?
Thanks again.

[Petros]

Have found that threatening to smash mine over the bonnet with a very large lump hammer helps.

[V8 Animal]

Plugged the end with tape this morning and drove the car to work.
Improved again wondering now not to bother with this vacuume unit at all.

[V8 Animal]

I might of cured the problem tonight!
Reconnected pipe and moved the dizzy back to it's original place,
Took out the stepper motor i had read a post earlier from blitzracing, and undone it it was only partily clean reconnected it but removed the tatty washer and used a fibre one.
Now the car drives better than ive ever had it!!
Maybe it was the stepper dirty or leaking air around that who knows.
All i can say is when i start it it goes to 2 thousand revs then settles to 900 a couple of seconds later and not sticking.
Giving it beans i now have no vibration aswell.
Thanks for the advice given,
A VERY HAPPY animal