Quick one on CU ignition timing

[T25rc]

Hi,

I have searched for the answer i'm looking for, but havn't seen anything.

I've timed up my CU yesterday at as close to 950rpm as i can get by ear, but see you have to take off the ignition stabilizers and put them together. My problem is that i can only see one plug (on the left hand carb) which seems to be that (the other 2 on the left carb and 1 on the right are to do with fuel cut off as far as i can see). So how can i plug *them* together?

Also, do i need to remove the crankcase breather hose?

I timed it to 5*ATDC with all electrics and vacuums attached (which are working), it has helped the low end power no end but it isn't as smooth at idle (though maybe i need to set the mixtures now?). The new problem is that it doesn't want to start when hot now, the starter is very slow and it sounds like the timing doesn't help (backfiring the piston?)

Could this be because i didn't disconnect the idle stabilization and the crankcase breather?

Cheers for any help

[81AirCooled]

The idle stab unit is the the nearer of the 2 black electronic boxes attached to the bodywork on the left hand side of the engine compartment. It has two leads coming out of it which need to be connected together when setting the timing. All vac hoses should be attached so don´t remove anything from the carbs. You will need to adjust the idle mixture once set so that might solve you´re idling issues.

Mine is set at 5° ATDC at ca. 950rpm (auto box) but should be around 850 rpm for a manual or so I´ve read.

I also have an issue when starting with a warm/hot engine and it can take up to 10-15 seconds of continuous trying to get it to start. At the moment I´m living with that because the van runs fine otherwise.

Good luck

[T25rc]

Cheers for that - for some reason i was under the impression it was the middle of the 3 plugs on the left bank carb.

Unfortunately, i can't find it, or it isn't fitted. There's the ignition module (which has one plug, and i know the engine won't run without) and a black box which when you pop off the front there's just some wires with plugs inside - none of which would fit together apart from the ones they're currently attached to.

Where some vans not fitted with the idle stabilization thing?

[BOXY]

There's a photo of the unit in this post. Maybe if yours failed it just got binned and the plugs joined together?

https://club8090.co.uk/forum/viewtopic.php?f=39&t=83496" onclick="window.open(this.href);return false;

[T25rc]

Hmm, i don't think i have that - or the plugs! Are the plugs in the ignition loom or somewhere else?

I will look again - is it something that would change the mixture you need to run at idle, therefore possibly skewing the fueling for the rest of the range. Or is it not very important really?

[Footprint]

I've got three sets of ignition wiring, two with and one without the idle stabiliser plugs. I think the one without plugs is from another vehicle that used the same ignition parts, (but I'm not sure what), as it's not altered - it has factory crimps and plugs on it.
Seeing as I don't have reliable idle stabiliser, (I've got two - they're OK when cold and cause a misfire when hot), I been running without one and therefore using the loom without stabiliser plugs - one less set of connections to have a problem with .

Now I'm sure VW bolted the stabiliser on there for a reason, but haven't found any noticeable deficit of not having one - although of course I can't be sure either of those I've got worked correctly, (or indeed, at all), even when they're not causing a misfire, Perhaps someone who owns a functioning one could comment?

[BOXY]

Are the plugs in the ignition loom or somewhere else?

There's another photo in the same post showing the the "loom", it's attached to the distributor.

[john1]

Now I'm sure VW bolted the stabiliser on there for a reason, but haven't found any noticeable deficit of not having one

Im sure it was fitted to help at idle, not cutting out. If its set up correct you wont miss it.

What are you setting your timing at idle and at rev 850rpm?

[Footprint]

I'm sure it was fitted to help at idle, not cutting out. If its set up correct you wont miss it.

Well quite, but I can't get a straight answer about what it is that it actually does, and specifically how, therefore what difference there is with and without. Of course being as one is intended to set the timing without the stabiliser connected suggests that it alters the timing, and the mere fact that's it's connected bewteen the pickup and the amplifier means that the only effect it could have is in altering the timing.

What are you setting your timing at idle and at rev 850rpm?

Set by the book, 5 after all vacuums connected, and it runs just fine. And now it has throttle spindles that don't flap about it's possible to get a reliable vacuum at the retard port too so the tickover is unsurprisingly improved.

Still like to know exactly what the stabilier does though.

[Tug]

In dont have an Idle stabiliser either. I have had my van for nearly five years and to be honest it runs fine. I have rebuilt my carbs (My shafts are not worn) 2 years ago and it runs great. I set my ignition timing as per the haynes and all is well.

[dugcati]

sounds like you may have the wrong dizzy/ignition system as what your saying suggests some donkey has put an 009 points dizzy on the van. Is there a vaccum advance unit on the dizzy do you know?

[T25rc]

Mine definately doesn't have it or the plugs - i also have the correct dizzy. I guess i'll just leave it, though i think the engine wants a little more advance.

[Footprint]

I've done some checking around - idle stabiliser and what it does:

As you may know, when the motor is running at idle, disconnecting the retard vacuum speeds up the motor appreciably, as the idle timing is set deliberately late with a shut throttle in order to reduce exhaust emissions, although it's not the 'ideal' spot to fire the mixture.
The object of the stabiliser is to advance the timing a dab if the idle speed drops due to an extra load placed on the engine at tickover such as turning on the lights which would add load to the alternator, and thus hold the engine speed at a suitable level.

An experiment: With a fairly accurate tachometer connected to my engine but no idle stabilser, tickover is about 850/875 rpm when hot, turning on everything electrical causes this to drop about 50 rpm, (ie a bit, I suspect that battery charge level may cause a difference here). Plugging the idle stabiliser in made no difference at all.

I suspect that the two stabilser units I have are duds, and thus don't do anything at all - except cause a misfire after running the motor for anywhere between 20 and 40 mins.

[dugcati]

I suspect that the two stabilser units I have are duds, and thus don't do anything at all - except cause a misfire after running the motor for anywhere between 20 and 40 mins.

.....much like the millions of others out there hence the reason nearly all of them have been binned off

[Footprint]

...much like the millions of others out there hence the reason nearly all of them have been binned off

True , still interested in what/how it does what it does.

However there has been a development: In a little box of bits I've just acquired, (for exactly the right price - ie nothing ), I've just got another one - and I have some new thoughts on how to test it and ascertain it's precise manner of function.

Watch this space*





*Assuming you're even slightly interested that is, I'd quite understand if you're not