Electronic vacuum advance?

[DC]

Is anyone aware of an 'electronic' vacuum advance? I have seen the MSD Boost Timer Master but this seems more geared to Turbos/Superchargers and is really for retarding.

Setting the context on this is rather long so please bear with me!

Last year I had a problem with getting the timing right on my new motor. Either I could set up a good idle but plenty of detonation on hard acceleration OR no detonation but impossible idle. By this I mean I had to continually blip the throttle to keep the motor running and the revs would gradually fall and engine try to stall, so blip again - no amount of idle speed adjustment seemed to help.

I was using a new Mallory magnetic with mechanical advance only.

I figured I needed more advance on tick-over which disappeared on load - EUREKA - vacuum advance! BUT unfortunately you can't convert this particular Mallory, so I fitted my old Mallory dual point with vac. advance. Problem solved the engine OK but recently (at Santa Pod and since) I find at revs over 5K the engine cuts suddenly. I have MSD6AL set to 6K limit so it should be progressive. I think the dual point is not coping so I'd like to fit my new dizzy again.

I would rather have a controllable electronic adjustment of the timing based on the pressure level of the intake manifold – any ideas??

[John Lind]

Hi Dave

I have not seen a device like that except maybe....

An engine management system (EFI with spark control).

If you set it up so it could read your distributor low tension and drive the ignition you could get it to do what you want by including a map sensor. You could optionally replace your mechanical advance at the same time.

It is probably more than you need at the moment so may be more expensive than you were looking for. If you did that you could let it control the ignition for now and then eventually you could replace your carby with fuel injectors.

Regards

John

[DAZPT]

There is a electronics shop chain here in Aust called Jaycar who have a electrtronic and vacuume advance that is adjustable, I have used this on several engins with good results. you may get some info on their website www1.jaycar.com.au/faq.asp or if not give me a call on my email address.The kit number is KC5202 I think,it is about $80 aust but needs to be assembled ,not to hard .hope this helps.
Darrell

[Gary Gibbs]

You can get stand alone crank triggered electronic ignition units that perform like the ignition side of a ECU from companies like electromotive. Rick Merz has such a setup on his GTD with webers.

[DC]

Thanks very much for the replies.

I am looking at the Jaycar kit at the moment, it seems to do what I need.

[Howard Jones]

Put in a mechancial advance only MSD billit distributor and be done with it. 34 degrees total advance all in by 2800 RPMs will work fine.

It will plug right into your 6AL. I have this very setup and it works very well.

[Howard Jones]

Put in a mechancial advance only MSD billit distributor and be done with it. 34 degrees total advance all in by 2800 RPMs will work fine.

It will plug right into your 6AL. I have this very setup and it works very well.

[DC]

Howard,

As I tried to explain above I did originally have a MSD mechanical only but the engine would not idle unless I advanced the ignition to about 20deg BTDC at static but then I got detonation on acceleration.

I have disconnected the vacuum pipe this w/e and set the timing to 10 BTDC (using a strobe) and it appears to run better on acceleration - haven't got stuck in traffic yet so I'll have to let it idle in the drive to see if its any different now. Maybe I have another problem with the idle other than timing??

[FredV]

Dave,

If it can help, i run a Mallory optical tiggered with mechanical vaccum advance on my 351W. The vaccum hose was never connected.
I always had the car setup like this and it works very fine.
I never understoud how it can works without variable advance but it works ! If somebody can hilight us ...