bmwe21.net forums

Recently I have added a vacuum advance onto my e21 where there was only retard, in the form of a 2002ti distributor, and have upped the fuel grade enabling me to be able to safely run much more advance. The consequence of this is a jump from 18hg to 25+hg manifold vacuum. Irritatingly this is just enough for the vacuum regulator to decide to stick open, or open on its own, making my rpms jump up to 2.5 grand. While I appreciate the function as it prevents my engine from blowing blue off throttle at high rpm, its not worth it to me to keep it attached. Is this normal behavior?
As of now I have a few paths, either the spring is just sticky somehow and needs cleaning, the regulator is bunk, or I need to get a aftermarket one and set it for about 30hg. I had another in my parts pile, but it seemed to want to fling open if you just looked at it wrong so idk.
Perhaps this is listed in the blue repair manual from bmw or chiltions. In any case I will have a look.

Did you connect the vacuum hoses as it should:

https://www.bmwe21.net/forum/viewtopic. ... e0#p248258

BertjeConti wrote: Wed Jun 11, 2025 9:34 am Did you connect the vacuum hoses as it should:

https://www.bmwe21.net/forum/viewtopic. ... e0#p248258

Interesting resource, though I must admit a bit hard to interpret, esp as its for carbed engines. In any case I will look at the diagram on my car. Though its not really an issue as I'm trying to run my ignition off of manifold vacuum for most efficiency, and limit off of manifold vacuum as that's what pulls oil through my valve stem seals.
In essence, its not stock, and I don't want it to be, I just want to know if I can use a new limiter or if I need to go to aftermarket solutions. Thank you anyways.
For context (my bad for not posting this earlier) its a 77 US 320i.

Ok, so you want some extra ignition advance at full throttle, i asume?

Beware that at full throttle there is almost nu vacuum in the intake manifold, so i guess your idea won't work.

The function of vacuum advance on a distributor is mainly to get a better idle. (Sometimes there is a temperature based air valve in this vacuum line, or a valve which switches on when airco is on to retrieve a stronger idle.

BertjeConti wrote: Wed Jun 11, 2025 8:23 pm Ok, so you want some extra ignition advance at full throttle, i asume?

Beware that at full throttle there is almost nu vacuum in the intake manifold, so i guess your idea won't work.

The function of vacuum advance on a distributor is mainly to get a better idle. (Sometimes there is a temperature based air valve in this vacuum line, or a valve which switches on when airco is on to retrieve a stronger idle.

No, I just want it for partial throttle and idle really. I just moved the vacuum canister line off of the throttle as that was really only for retard. (It would present no vacuum to the line when cruising but leave vaccum in the manifold)
Personally I just crank up the advance tbh, and it's already a bit too much past 5000 on mid grade.
As for appropriate line connection they're are done up right, just direct to manifold.

Do you know 123ignition?

BertjeConti wrote: Thu Jun 12, 2025 5:55 pm Do you know 123ignition?

Yeah, but I don't want to drop that much money on something like that yet. I'm getting really good results so far, and again the ignition is working a treat, its the vacuum regulator that muffs it up. In fact I feel much better throttle response at higher advance, but the amount of pinging is unbearable, and with my explorative move to midgrade, there may be more efficiency and performance at premium as it really boosted my idle off idle and full out performance. Esp as we just had a 96 degree heat wave. In that instance on regular, tuning down to avoid pinging removed the guts from it.
I must also admit, I am quite partial to the old way of doing things. Plus I like to tinker with crap though it may be a bit foolhardy to do so.

Right now I'm thinking about installing this underneath the intake where the egr filter would otherwise go
https://www.amazon.com/Newsmarts-Vacuum ... 179&sr=8-8
However the issue is it doesn't pull more fuel like the other, so it would just lean out the mixture which would be potentially dangerous. Or it might be ok as it would only be on deceleration.
Edit: I also have some concerns about heat resilience with respect to the plastic.