Modify vacum-advance dizzy to "throttle-cable-advance&q

[purity]

I just got this idea; what if I were to use a vacum-advance or SVDA dizzy with carbs that don't have a vacum-port, could I connect the throttle cable to the same pin that the vacum advance pot connects to, and thereby get the wanted advance? I realize that the cable might move too much back and forth, but this could be solved by building some kind of pulley system.

Only a thought I have
_________________
- '67 1300 (Original)
- '71 1302 (Daily driver, TIV-engine going in)

[Glenn]

You're thinking too much.

You can not correlate ignition advance to throttle position.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

עַם יִשְׂרָאֵל חַי

[Matt Cramer]

[[email protected]]

that won't work.

But if you want to think outside the box, advancing under light loads is the same as RETARDING UNDER LARGE LOADS. If you can retard the timing if MAP drops under a threshold (like 5" of vacuum), it will also work. It can't be like a switch, it has to have some linearity to it, but it will do the same job as vacuum advance.

John
Aircooled.Net Inc.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[purity]

Not even with a SVDA? The vacum advance would be controlled by the throttle position anyway, because the vacum comes from how open the throttle valve inside the carb is.

I got the idea from reading about computer controlled ignition, where you have a throttle position sensor.

EDIT: Didn't see John's post before posting this
_________________
- '67 1300 (Original)
- '71 1302 (Daily driver, TIV-engine going in)

[[email protected]]

it's NOT controlled by throttle position. Drive down the road at 1/8 throttle up a hill, that's a high load light throttle position, when you should NOT have vac advance. Now drive down a road at 1/2 throttle down a hill, that's a light load position when you can use the extra advance.

If no hill, same thing applies depending on what gear you are in.

John
Aircooled.Net Inc.
_________________
It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
http://www.facebook.com/vwpartsaircoolednet
and get a 5% off code for use on one order for VW Parts ON OUR PARTS STORE WEBSITE, vwparts.aircooled.net

[cyleriggs]

As john said the throttle plate position won't always correlate the same with engine vacuum, throttle position sensors aren't enough, hence MAF and MAP sensors.

just my .02.

[purity]

Allright I guess I'll leave this be then, and just go for a distributorless EDIS-system when I can afford that. Thanks for sharing your wisdom!
_________________
- '67 1300 (Original)
- '71 1302 (Daily driver, TIV-engine going in)

[Matt Cramer]

[Eaallred]

Also,

I don't know of any EFI that dictates timing based on any input from the TPS.

Timing maps are a combo of RPM and MAP. Same two things an SVDA bases it's timing from. It's just not (as) adjustable like a full timing map is.
_________________
Eric Allred

You have to remember something: Everybody pities the weak; Jealousy you have to earn.

[miniman82]

[pikeman48]

hook up the dizzy advance to a separate cable control,and adjust advance as needed. Ford and Harley both did it,why not you?
_________________
if it has wheels or tits,it will make your life difficult!!
1962 type 1-gone,but not forgotten
1971 type 1 vert-sold
sand rail-stripped and scrapped
1968 Empi Sportster

[cyleriggs]

[pikeman48]

The model T Ford had 2 levers on quadrants below the steering wheel. One was throttle,the other was spark advance. With the "buzz box" ignition,sometimes you could start a model t by pulling both levers to full position-if the engine was in a sweet spot in the rotation when it was shut off,those things would start and run with not being cranked over-no crankshaft movement at start-up. For years the left handgrip on a Harley was spark advance- all the way thru the panheads,IIRC.
_________________
if it has wheels or tits,it will make your life difficult!!
1962 type 1-gone,but not forgotten
1971 type 1 vert-sold
sand rail-stripped and scrapped
1968 Empi Sportster

[Eaallred]

[miniman82]

[Eaallred]

[Stuggi]

[Glenn]

The mechanical advance on a SVDA is like a OO9.
_________________
Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

עַם יִשְׂרָאֵל חַי

[miniman82]

There's already a much more elegent solution to all this stone age hacking of distributors- it's called Megajolt. Carbs don't have vac take offs? No biggie- just tap each runner, connect the individual tubes together, and use the MAP version of Megajolt. Then you can program any curve you want, including crank retard, vac advance, pressure retard, or whatever curve you feel like on that day.
MJ also has a rev limiter, and can control water injection, shift lights, ect. Oh, and the benefits of crank triggering.
_________________
Build thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=212747