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Vacuum advance on dizzy

Bizarre - July 14th, 2012 at 05:55 PM

My mates bug has hesitation on acceleration

The vacuum advance doesnt seem to be working enough.
How free should they move???
There is suction from the carb - but you have to suck hard to see any movement on the distributor.

If you suck really hard the engine seems to rev easier

So - should the more easily with just a light suck or are they fairly resistive??

shokwave2 - July 14th, 2012 at 06:58 PM

Mine moves easily if you suck on the hose from the vac advance. Does the advance if hold if suction is held with your tongue? If it doesn't hold then the vac cannister is stuffed. If it takes a fair bit of suction to get the advance to move you may have to give the distributor a bit of a service and re-lube the moving parts.

psimitar - July 15th, 2012 at 12:16 AM

remove the vac can from the dizzy and suck on the little tube. The cans armature should move in nice and easy. If not the diagraphm may have a small hole.

Now manually check to see if the dizzy vac plate rotates freely with your fingers. If not then use WD40 and wiggle it back and forth till it frees up. If it don't free up you'll have to remove the vac plate and clean the spindle and vac plate bush up as may be a bit rusty

matberry - July 15th, 2012 at 09:23 AM

Is it a new replacement distributer or an original Bosch/VW unit? Many of the new units are extremely bad quality. If VW, check the part # matches your engine. You could post details here or do the research. Not all vac distributers are created equal. The vacuum signal varies between engines as there are many MANY variables.

Bizarre - July 15th, 2012 at 12:18 PM

Matt

This is a pretty original matching number 1975 R&P L bug - just in a pretty sad sate.
It has sat for a long time but it has real good bones

Its his son's bug so I dont get much chance to look over her.
I have dug up a 009 that they can try and then I can have a good look at the other one and see what the matter is

You had to suck a lot harder than what the carb was to get any sign of movement from the dizzy

68AutoBug - July 15th, 2012 at 05:27 PM

Quote:

Originally posted by Bizarre
My mates bug has hesitation on acceleration

The vacuum advance doesnt seem to be working enough.
How free should they move???
There is suction from the carb - but you have to suck hard to see any movement on the distributor.

If you suck really hard the engine seems to rev easier

So - should the more easily with just a light suck or are they fairly resistive??

sounds like the vacuum isn't working OR
what happened to Me on two occasions ;
the accelerator cable had slipped in the collar on the carby
as its always well oiled and the new screw I used didn't grab too well on the cable end... so NO vacuum advance..!!

OR the vacuum unit is cracked due to wear...

and its actually running like a 009 dizzy... does..

the inside of a distributor should be oiled at least when the oil is changed... just a couple of drops..
some dizzies have an oil felt in the centre under the rotor..
which should be oiled too..

New vacuum units can be bought... some are expensive..
should say.. most... lol
there is a number on the vacuum units arm...

I am running a new Bosch SVDA distributor from aircooled.com in the USA... I thought My German Bosch 009 was working OK , until I changed over... YIKES
A BIG difference in advance....
and so smooth on acceleration.... well worth the change..

LEE

matberry - July 15th, 2012 at 09:54 PM

Quote:

Originally posted by Bizarre
Matt

This is a pretty original matching number 1975 R&P L bug - just in a pretty sad sate.
It has sat for a long time but it has real good bones

Its his son's bug so I dont get much chance to look over her.
I have dug up a 009 that they can try and then I can have a good look at the other one and see what the matter is

You had to suck a lot harder than what the carb was to get any sign of movement from the dizzy

The dissy is regularly the wrong one, so vac signal may or may not match the distributer. The part # and engine # will verify. As stated the advance mechanism needs to be operational and free in it's movement, but if the advance is siezing they tend to not return to inital advance easily as the springs aren't super strong to return the advance plate.

psimitar - July 16th, 2012 at 01:20 PM

Quote:

That's why I wrote what I did. Yes the dizzy has to match the engine but you shouldn't have to suck that hard to get movement.

Search the web for the few sites that list dizzy numbers to engines and year of production.

if it's been sat a good while I reckon the vac plate is sticking.

BRUTUS - July 17th, 2012 at 05:01 PM

There is a place in Melbourne that I have had repair/reco advance units in the past... If you have an original one and want to keep it. I think I gave the details once before.

Ah. Here it is/was:
"... old dsitributors can be fully recoed/refurbished to original spec's, in Melbourne. Also the vac units can be done - are sent away for rebuilding (takes longer as they send them elsewhere).
At: Performance Ignition Services, Nunawading. 03 9872 3644
This may cost as much or even more than the new-cheap unit, but should give a "good as neu" and hopefully original-Deutsche unit (if you have the correct one in rebuildable condition to start with).
Have had two done so far and have been very pleased with results."

Bizarre - July 17th, 2012 at 07:30 PM

Thanks Brutus

The 009 has made a world of difference - that is scary.
So there is obviously a problem with the unit

I have asked my mate to bring it in to me and give me the engine number

matberry - July 17th, 2012 at 08:18 PM

Quote:

Originally posted by Bizarre
I have asked my mate to bring it in to me and give me the engine number

You may want him to get details of carb as the engine number these day's won't guarantee what carb and displacement the engine has.