DUI w/mechanical advance only

[Javabean]

I'm looking for advice and opinions as I look to upgrade my ignition from the Load-o-Matic to the DUI. I see that a full mechanical advance version is available and I'm thinking this may be a good option for my setup. I'm running an Offy 3x1 with an Autolite 1100 (SCV version) as the center carb. on my 200. Everything seeme to runs great at low RPMs but car falls on it's face when the outer carbs open under load. I know I still have a lot of tuning to do, but I believe the lack of centrifugal advance is really causing the majority of the problem. Now I could block off the SCV and run vaccum from the manifold, but the thought of not having to worry about the vaccum is pretty appealing.

I guess my question is would a full mechanical advance DUI be worth while or will part throttle performance and driveability suffer too much due to the lack of vacum advance?

I've never run a dizzy with out vaccum advance, so I'm just not sure what to expect. FYI - this is not for a daily driver.

Thanks,
Jay

 

[wallaka]

There is no reason to not run a vacuum advance that I know of. I believe that your problems are probably a direct result of the Load-O, and when you get rid of that, you will see a great improvement.

The reason for dual-advance systems is to offer better driveability, performance, and economy in the changing conditions of driving on the road. So, I would run a vac advance model DUI over the centrifugal-only.

 

[NC-Fordguy]

I'm running a DUI(Mech advance only) on a 1966 Bronco with a 170

I plugged the scv port on the autolite 1100

Haven't experienced any flat spots or stumbles with this set-up

If you do go to a DUI make sure you find a switched 12 volt source for the distibuter to work correctley. The old ignition wire has a resister in it that only puts out 6-9 volts.

 

[PaulS]

The only thing the vacuum advance does is provide extra advance during part throttle operation to increase milage. I get 30% better milage on my V8 with a vacuum advance than I do without it. 15mpg without and 20 to 21 with. I have no idea how this will effect your six.

 

[fordconvert]

Do the models without vacuum have more mechanical? If not why not get the one with vacuum and and try it hooked up and not? Most engines with variable loads run vacuum advance. Im sure the load o is most of your problem now, it was never designed for the 3x1 setup.

 

[Javabean]

Thanks for the replies!

That's a good question about the amount of advance. I'll drop them a line on Monday and ask.

NC-Fordguy, do you know how much advance your are running or if it's different from the dual advance version?

Just to give an update, I think I've got it running pretty decent right now with the LOM. I bumped base timing to 12* and took it out for a ride today. Man that made a huge difference! It ran pretty hard once moving and she cruised great. Just didn't have a real quick response when I slammed the pedal to the floor under load. I had to go easy on the gas when starting off, but was able to spin once the RPM's got up. She never did that with the stock 1V!!!

I still think I need better ignition. A better cam wouldn't hurt either.

 

[PaulS]

The mechanical advance is set to a max of 32 to 36 degrees (with the initial advance included. Vacuum advance is not figured into the overall maximum advance because under a load it goes away. The vacuum advance only works at part throttle conditions and does nothing for power.

 

[NC-Fordguy]

Thanks for the replies!

That's a good question about the amount of advance. I'll drop them a line on Monday and ask.

NC-Fordguy, do you know how much advance your are running or if it's different from the dual advance version?

.

Are you referring to timing advance??? If so looks like around 10 degrees BTDC(pointer only goes to 6 degrees)

I used both a timing gun and vacume guage to set the timing

 

[Javabean]

I was looking to see if you knew how much mechanical advance your dizzy had built into it. No worries though, from the responses here and others I've talked to, I'm leaning towards the dual advance version. There seems to be good reason for vaccum advance and not enough against it.

 

[salty_monk]

I've run without vac advance before on two different vehicles incl the falcon. It will affect MPG, running at idle, throttle response at low throttle opening & a bunch of other stuff.
I now run with Vac of manifold direct with no problems on the Falcon using a DSII & a GM HEI module. Getting about 17mpg but doing a lot of "round town" driving. That's on a 200. My carb is a Holley 1 barrel.

Dan