Vacuum advance

Bjamo · Posted: Tue Jan 08, 2013 1:52 am Post subject: Vacuum advance

So, today I accidentally left the vacuum advance disconnected. I only remembered after I'd gone to the shops and back. The odd thing here is that I noticed absolutely no difference in how it drives with the advance disconnected. Is this normal? Could I have it hooked up to the wrong port on the carb? Running a h30/31 carb with an SVDA from ACN. Sorry if this is a stupid question, I'm fairly new to ACVWs.

Weevil_Kneevil · Posted: Tue Jan 08, 2013 2:10 am Post subject: Re: Vacuum advance

Bjamo · Posted: Tue Jan 08, 2013 2:22 am Post subject:

Single Vacuum, Dual Advance distributor. So it has centrifugal and vacuum advance. ACN is Aircooled.net Very Happy

Weevil_Kneevil · Posted: Tue Jan 08, 2013 2:25 am Post subject:

Aah....

Weevil_Kneevil · Posted: Tue Jan 08, 2013 2:28 am Post subject:

Googled the dual advance distributor... Now I'm confused.... I should stick to things I know.... like eating burgers.

Bjamo · Posted: Tue Jan 08, 2013 2:38 am Post subject:

This is the one. Very Happy

http://vwparts.aircooled.net/Aircooled-Net-SVDA-Distributor-p/acn-svda.htm

Kevinx · Posted: Tue Jan 08, 2013 5:15 am Post subject:

You need to hook up a timing light and see if everything works, and double check your initial/ final timing. If I leave my advance hose unhooked. It stumbles off idle
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In life there is but one way out

andk5591 · Posted: Tue Jan 08, 2013 5:27 am Post subject:

You DID get one that is set up for your carb - not the generic one - they sell one specifically for the low vac signal on an H30/31, which is not the same as the one for a 34PICT-3.

I agree that you need to verify with a timing ling what is going on. One thing that I would look at is, if you carb has any age to is, is a clogged vac port on the carb.
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

Bjamo · Posted: Tue Jan 08, 2013 6:22 am Post subject:

Indeed, I selected the '30-3 and 30/31, Solex/Bocar/Brosol/Pierburg' option. Is this what you meant?

I'll check the timing & vacuum ports tomorrow. Thanks guys!

Tim Donahoe · Posted: Tue Jan 08, 2013 9:09 am Post subject:

I DO know without a doubt that my H30/31's vacuum is not strong enough to further advance my Bosch SVDA 034. So I wonder why AC's is doing (not doing) the same thing?

Tim

Relyt · Posted: Tue Jan 08, 2013 9:16 am Post subject:

The vacuum line hooked up should be adding about 10* advance under load and 0* at idle.

Use a timing light and check your advance with and without the vacuum line hooked up, if there is no difference either your vacuum can is not working or it's not the right distributor for your carb's vacuum signal, or there's something wrong with the vacuum ports on the carb.
_________________
69 Beetle - Daily driver
1600 SP (unknown history)
30 PICT 1 w/power circuit (Volkzbitz)
205T (Bill)

andk5591 · Posted: Tue Jan 08, 2013 11:08 am Post subject:

If you have access to a vac gauge - measure it at the carb at various throttle positions and contact aircooled.net with what you have found. Maybe they sent the wrong one?

I think you already said this - but with the hose one or off, your idle speed doesnt change, correct? Reason I am asking is that on a 28PICT one the passages was clogged and it was pulling vacuum at idle.

You are sure you are on the correct port (I dont know which one it is since I dont have a 30/31 on anything at the moment. but guessing its on the side)
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

Bjamo · Posted: Thu Jan 10, 2013 1:38 am Post subject:

So I'm 90% sure I've just had it hooked up to the wrong vac port all this time. Rolling Eyes

I tried it on two different ports with the timing light hooked up. On the original one, flick the throttle, no advance until the revs go up. Hooked up to the second one, flick the throttle, immediate advance of ~10 degrees. Went for a spin, it seems a little more responsive off idle. All a good learning experience for a newbie c: Cheers guys!

andk5591 · Posted: Thu Jan 10, 2013 5:41 am Post subject:

Cool! It was the one one the side, right? Oh - and you do have a bend in your line right? VW vac lines are usually copper and loop up before going to the distributor. The purpose is to prevent any gas from getting to the vac canister.

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_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

ashman40 · Posted: Thu Jan 10, 2013 8:56 am Post subject:

andk5591 · Posted: Thu Jan 10, 2013 1:00 pm Post subject:

Ashman, they have one of Johns SVDAs that is set up for the H30/31
_________________
D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them...

evilphoton · Posted: Thu Jan 10, 2013 1:03 pm Post subject:

I use "D" to for vacuum advance. it pulls to 10" just off idle.
_________________
'71 SB - 08/1970
[s]34/3 (70/75/75z/135) - 26MPG[/s]
A pair of Kadrons
VW 028 DVDA, stock 1600 DP
'00 VFR
'01 Blazer

Bjamo · Posted: Fri Jan 11, 2013 12:20 am Post subject:

Thanks, I do indeed have a bend in it Very Happy

Yeah, it's got all 4 of those ports. To begin with I had the vac advance on A (which I recently found seemed to make no difference with the vac advance line connected/disconnected) and the Autostick vacuum line on D. It seemed to go and shift well enough. After doing some searching a few days ago I moved the A-S hose from D to C, definite improvement in shift quality. (I know this Autostick info is irrelevant to this thread but hopefully it'll be useful to someone in the same situation searching for info Very Happy

)

After the timing advice from the guys here I moved the advance line from A to D. Connected to A there was little to no vac advance off idle, connected to D it advances ~10 degrees instantly once the throttle is opened, and seems to be snappier off idle.

To summarise, A and B are plugged, A-S hose is on C and vac advance is on D.


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