locking out the distributor

[john h]

Hi All,
Can anyone outline for me the procedure of locking out the mechanical advance and the vacuum advance?  Also I need to try and understand indexing the dist.  I'm looking at EFI kits and trying to decide if I should get one capable of controlling the timing.

Thanks.
John

[Chryco Psycho]

2 ways to do this , order or find a lean burn dist from the late 70s or early 80s , it has no advance mech .
 If you want to use a dist with advance you can use an allen wrench & turn the srew inside the vacuum pot all the way CCW to the end this eliminates any movement there ,, weld up the slot in the mechanical advance plate under the pick up soit will still allow the pins into the plate but without movement ,, that  will lock the upper shaft so it cannot move .
 EFI with timing control is awesome , you can create any curve you want or need far more accurately

[john h]

2 ways to do this , order or find a lean burn dist from the late 70s or early 80s , it has no advance mech .
 If you want to use a dist with advance you can use an allen wrench & turn the srew inside the vacuum pot all the way CCW to the end this eliminates any movement there ,, weld up the slot in the mechanical advance plate under the pick up soit will still allow the pins into the plate but without movement ,, that  will lock the upper shaft so it cannot move .
 EFI with timing control is awesome , you can create any curve you want or need far more accurately

Thanks for the info.  I Appreciate the feedback.

John

[john h]

2 ways to do this , order or find a lean burn dist from the late 70s or early 80s , it has no advance mech .
 If you want to use a dist with advance you can use an allen wrench & turn the srew inside the vacuum pot all the way CCW to the end this eliminates any movement there ,, weld up the slot in the mechanical advance plate under the pick up soit will still allow the pins into the plate but without movement ,, that  will lock the upper shaft so it cannot move .
 EFI with timing control is awesome , you can create any curve you want or need far more accurately

I was looking into the lean burn Dizzy.  I'm wondering what you do with teh 2nd set of pickups?  can you just not hook them up and use the primary set and index and phase the distributor?
John

[Chryco Psycho]

yes
Or you can have magnets installed in the crank damper exactly 90* apart & use a cranks pick up for more accuracy as I have done 

[BFM_Cuda]

You could also use a mechanical advance limit plate and then unplug the vacuum advance to hold the timing.

http://www.ebay.com/itm/Mopar-Ignition-Timing-Limiter-Plate-w-Springs-/321755095569?hash=item4aea192211:g:NSEAAOSw~OdVVOVp&vxp=mtr

[Chryco Psycho]

That will work too , I didn't realize Dons plate has a lock out position

[john h]

You could also use a mechanical advance limit plate and then unplug the vacuum advance to hold the timing.

http://www.ebay.com/itm/Mopar-Ignition-Timing-Limiter-Plate-w-Springs-/321755095569?hash=item4aea192211:g:NSEAAOSw~OdVVOVp&vxp=mtr

great web site.  Thank you.

[john h]

I was checking my timing tonight.  I am using a standard 2 wire Mopar distributor that was supplied with the 360 crate motor. it seems to have 39* mechanical advance at 2500 RPM.  if I hook up the vacuum advance, it will go up to 53* at 2500 RPM.  why in the world would it have so much mechanical advance?  I know I can limit the vacuum based on earlier post by Chryco by turing the screw inside ccw.  just does  not seem to make sense if theses things are happiest with 34* total.  without a limiter plate oR other means described above, I would always be way too advanced and it was factory supplied.

[mopar jack]

39 degrees is your total advance. You need to know what your initial advance is to determine the amount of mechanical advance.

[john h]

39 degrees is your total advance. You need to know what your initial advance is to determine the amount of mechanical advance.

I'm disconnecting the vacuum advance, running the throttle up and increasing the number on the back of the timing light until the timing mark hits zero.  at 2500 RPM the zero mark on the dampener is 39* on the timing light.    the idol advance is set to 12* at 650 RPM. 

[john h]

I was messing around with this again tonight.  I checked the mechanical advance total is 39* at 24 or 2500. Idol timing (initial) is at 12* BTDC I hooked up the vacuum and I get 55* at 2500 RPM.  I turned the alan screw all the way in (clockwise) until it stopped and I still get 55* total with Vacuum at 2500.  I turned it all the way out, (CCW) (got worried it would drop out into the dist) it's still Advancing to 55* at 2500 RPM.  Maybe I need to pull it out and get it on The bench so I can see what is actually happening inside when adjusting this alan screw.  What am I missing? I know I can skip running Vacuum advance and it should run better because it's not so advanced.
If I have 39* total Mechanical advance with 12* initial, I think that means I actually have 27* Mechanical advance.  so I need to turn down my Initial to 7* BTDC?  IS that correct.  7* plus the 27* Mechanical = 34* Total Mechanical.  The mopar book suggests 12* initial.
AmI thinking about this all wrong?  Do I possibly have a blown Vacuum advance unit that won't limit with the Alan screw?

thanks for your thoughts.
John

[Chryco Psycho]

Baking out the allen srew to the end should prevent the advance plate from moving , I do this all the time , it will not fall out but if it is turning it should go 13 turns & you will hear a click as the last thread turns out , what you need to do is limit the mech dvance by shrtening the advance slots so you can leave the timing at 12* without over advancing past 36*

[john h]

DO I want 34* Mechanical but more , maybe up to 45* at cruising speed say 45 mph and above? OR is my mark 34* total (initial, mechanical and vacuum)?
I will keep backing the screw out since you say it won't fall out.  I will go all the way back to see if I get a big change first.

Thanks for the info.
John

[73_Cuda_4_Me]

Most members will tell you to forget the vacuum advance, and set mechanical to 34-36 degrees total at 3000-3500 RPM.

Remember that the screw adjustment on the vacuum advance DOES NOT control the amount of vacuum advance, only the AMOUNT OF VACUUM needed to pull the advance arm... The length of the slot in the vacuum arm controls the amount (shown in attached photo). This one is 8.5 degrees vacuum at dizzy (17 degrees advance at crank).

If by some chance your vacuum advance spring is broken (i.e. rusted a coil out), NO AMOUNT of adjustment will prevent the vacuum advance from working... it will take same amount of pressure to push that arm in by hand no matter where the adjustment screw is positioned. Mine has definite variation depending on where screw is at, so mine is working correctly (but I leave it disconnected anyway).