Ignition Advance - Electronically Assisted Vac Advance

[the_mighty_one 0]

Right,

 

im having a few issues with my car atm, namely that i cant go for max power as it pinks lower down the range.

 

Ive come up with a solution, quite a cheap one at that (about £10).

 

Ive got a combination of a few microchips and a vacuum solonoid.

 

My thinking is when the car goes over threshold revs [4000rpm] it works the vac advance on my dizzy to bring my timing round to full advance, and when under the threshold it backs off my advance to stop it pinking. Ive got all the circuitry working, but now im stuck!

 

When vacuum is applied to the vac advance capsule does it do as the name suggests and advance the timing?

 

If so, how much does it advance the timing by?

 

Now if someone would be kind enough to answer these questions, ill go get in the garage and sort it on friday and report back!

 

If it works then i'll keep it and use it on my car (and possibly sell it as a kit?), and if it dont ill tell ya!

 

Cheers people!

Edited March 7, 2006 by the_mighty_one

[M3Evo 0]

Why not adjust the dizzy so that it doesn't pink?

[DrSeuss 0]

or why not use proper mappable ignition? What your talking about sounds too simplistic, but with only slightly more complex programming your almost at the point of mappable ignition anyway.

[Anthony 1,003]

Are you running higher than standard compression so that the standard ignition advance curve is wrong? If you are then fair enough, but if you're still running standard then either you're simply trying to run too much advance, running on 95RON fuel, or you have a problem with the dizzy advance mechanism (try another known-good dizzy)

 

What you're suggesting would probably work to a degree, but it's at best a bodge and one that's unlikely to work as well as you're hoping.

 

Something like Megajolt is fully mapable ignition and cheap as chips to buy the unit and raid the scrappy for the Ford ignition bits - that will give you the ability to properly map the ignition and get some decent improvements in power/torque/economy over the clockwork dizzy

[pugrallye 0]

hmmm, i think your best asking someone with an availiable and relevant ignition map to give you degrees of advance/ retard.

Can see where your coming from doing this, psuedo charge pressure solenoid on modern cars controlling actuator movement, possible but fiddly!

[Rob_the_Sparky 9]

The major flaw with the argument being that vacuum advance applies advance only when there is depression in the inlet manifold. This is mainly on the cruise and overrun, not with a fully open throttle.

 

For now I have backed off the advance as I too suffer (due to high compression). I have a "tweaked" SBC dizzy I got second hand which has certainly made things better but is not a cure. If you don't want to do proper mappable ignition then try taking a look at the thread about modded dizzys (fairly recent and in this area).

 

Rob

[the_mighty_one 0]

hi.

 

im using a small vac tank to store vacuum untill it is needed, ie on full throttle, so manifold vacuum is not a issue.

 

and yes, im running a lot higher compression [car spec is xu10j2 head, grpA max torque cam and a pair of 40 webers wiv 37mm chokes].

 

there is no programming required, its simply a case of 3 chips hardwired on a circuit board and a few resistors. much cheaper and much simpler than mappable ignition as it will solve my low rev's pinking issue which is all i need.

 

just need to know by how many degrees the vac module advances the dizzy so i can retard my dizzy by a suitable amount.

 

cheers again.

[the_mighty_one 0]

right

 

got my system up and working, and it seems to work fine!

 

on idle if u activate it the engine revs up another 500rpm (decided to use a 405 vac advance capsule as it pulls it more!).

 

so ive backed off my dizzy a little to stop it pinking, then when its at higher revs i switch it on and hey presto full advance again.

 

well actually slightly more that before as i found out where my ignition timing was before, then worked out the range of advance the vac module gives [for eg 10degs] then set it so at full advance its half the range over [+5degs] the original and on no advance its half the range[-5degs] below original so i get less advance on low rev and more on high rev.

 

it works a treat, no pinking down the bottom, and ive got more advance up top, its cured the cars hesitation when flooring it above 4500rpm too so that was a big bonus, and it seems to pull stronger right up to 7500rpm.

 

next step is to wire up my rpm to dc circuit so i can automatically trigger the vacuum system

Edited March 16, 2006 by the_mighty_one