vac advance/retard query

[nrxx]

Engine has been running well bu sounds unhappy recently, lost a bit of sparkle/response to the throttle. I suspect the vacuum unit but sam not sure of best way to check.
With the engine running (tickover from cold), I unplugged the vac pipe from the dizzy and there seemed to be a slight drop in revs but, sucking and blowing on pipe makes no change in engine speed. Does this indicate knackered vac unit? Is replacing the unit a sraightforward job?

Thanks
Nick

[nrxx]

Sorry, 1.9 DG 1987
Nick

[HarryMann]

Quick answer, no, you need to strobe it rather than using subjective criteria like listening

Firstly, has it got the double vac unit, adv. & ret. ? If so which one are you sucking on

More later...

[nrxx]

Thanks Harry
Not sure really, only has one vac pipe! Is there any way of finding out without a strobe, I 've read the other threads but am still not clear (!). According to one thread I should be able to see the back plate moving if I suck/blow without engine running but I'm not sure of procedure, I guess that's rotor and dust cap off?
Thanks again
Nick

[ghost123uk]

Thanks Harry
Not sure really, only has one vac pipe!

So it's the single (later) type

According to one thread I should be able to see the back plate moving if I suck/blow without engine running but I'm not sure of procedure, I guess that's rotor and dust cap off? Thanks again - Nick

Yep, that is a basic test to see if the unit has not jammed up or has a damaged diaphragm.

As has been said though, you could do with getting a strobe on it and checking for correct vac advance timing, even if it is just to eliminate it from your trouble shooting.

[HarryMann]

From: https://club8090.co.uk/wiki/Pe ... gnition_02

[nrxx]

Thanks, will get strobe and check.