MP Dizzy - clockwise or counter clockwise on vac adv

Posted By: Chilort

MP Dizzy - clockwise or counter clockwise on vac adv - 04/06/10 11:16 PM

I recently purchased a Mopar Performance dizzy for my 440. According to the info from the Tech archive:
http://www.moparts.org/Tech/Archive/elec/29.html

I have the Mallory built unit. I have already adjusted the mechanical advance to reduce it by a few degrees.

I now need to reduce the vacuum advance. The link above says to reduce the vacuum advance down to 10* total but looking at my total timing plus the information provided through Mopar with these dizzies (though it didn't come with mine.....) I can run with up to a total of 56* with the vac advance. Based on my mechanical timing I don't need to take the vacuum advance down by much. The problem is, I don't know which way to turn ... literally.

The info in the tech archive says to go counter clockwise to reduce the advance but the info with the dizzy says to go clockwise. Which is it?

Posted By: RapidRobert

Re: MP Dizzy - clockwise or counter clockwise on vac adv - 04/07/10 01:11 AM

Quote:

The info in the tech archive says to go counter clockwise to reduce the advance but the info with the dizzy says to go clockwise. Which is it?

on all oe Mopar dizzys CCW requires more vacuum to start the slope (in effect reducing the advance). I wouldn't think the Mallory ones would be different. EDIT you didn't ask but I'd set your initial where the cam/eng wants it then w that figure in hand shorten the slots to get 36-38 total w the vac adv disconnected and the hose plugged then play w the springs to get the lightest spring combo that will keep you JUST UNDER the pinging point as you go thru the gears @ WOT on your hottest/driest day and at whatever rpm that lets your total come in at is OK then hookup the vac adv and at a steady cruise on the hiway at an RPM above where the mechanical adv is maxed out turn the 3/32" allen wrench for the adv to come in as fast as possible (CW) again staying JUST UNDER the pinging point at this PART THROTTLE (steady rpm cruise) out on the highway speed. I'd highly suggest doing them in order and you can WITH CARE also increase/decrease the AMT the can offers which is different from the slope(the vac amt that the adv start/ends at which is changed by the allen wrench) any particular can can provide by filing the tabs (for more travel) or epoxying feeler gauge strips under the tabs (on the arm)(to limit travel) or sub in another can, if you want to go that far to get everything dead on perfect.

Posted By: Chilort

Re: MP Dizzy - clockwise or counter clockwise on vac adv - 04/07/10 03:56 AM

I'm still playing. I'm not shooting for perfect either, just good.

It is a .040 over 440. The pistons are way in the hole (0.100). It has Eddy heads that have been milled to get a CR around 9.2:1. The cam is a Lunati 60303. The cam was centered according to the suggestion of Lunati and it was verified.

It likes the initial around 17*. I'm using a timing light and a vacuum gauge. The engine has just over 500 miles on it. I've done some nearly full throttle runs but no full throttle yet. This is in a '68 Sweptline pickup with no weight in the back and, well, full throttle doesn't do anything bu burn up tires. Plus, I've got a 2.76:1 rear gear so trying to do full throttle runs in top gear means I'm carrying a lot of speed (not the best choice where I live).

I have the mechanical set so that with the initial I am getting about 40* total without the vacuum advance. I know I need to back that down another couple of degrees but since I haven't done full throttle runs I haven't worried about it that much yet.

What I do know is that I get some rattle at part throttle especially under load (up hill). I'd like to take a little of the vacuum advance out of it to see what that does.

My daily driver died a couple of days ago so I'm driving the truck daily probably for the rest of the week.

Posted By: RapidRobert

Re: MP Dizzy - clockwise or counter clockwise on vac adv - 04/07/10 04:02 AM

Quote:

What I do know is that I get some rattle at part throttle especially under load (up hill). I'd like to take a little of the vacuum advance out of it to see what that does.

2 turns CCW w the 3/32" allen wrench

Posted By: Chilort

Re: MP Dizzy - clockwise or counter clockwise on vac adv - 04/07/10 04:07 AM

That's what I was looking for. Thanks.