Vacuum advance removal, is it possible?

[604]

Is it possible to remove for good the vacuum advance canister from a new MP distributor? I do not use it. And the darn thing makes it a royal pain to get to the hold down bolt. Would be nice to just have it gone. If not is there a plug and play distributor with out one that works with the Mopar electronic set up??? Thanks!!

 

[discharger1332]

there is a eloctronic lean burn dist. with no vacum adv.

 

[Mopar to ya]

I took out my vacuum advance and put in an MSD Pro Billet dizzy and a Mopar Performance MSD-6 box. Pretty nice way to go. If you aren't using the vacuum advance, you aren't getting the most out of your motor. You can certainly find distributors with mechanical advance instead. You need that advance at higher rpms.

 

[67Dart273]

"Back in the day" we used to braze or screw/ pin stock advance plates to do this. I have not researched this in awhile, but it seems to me (the old Direct Connection?) used to make replacement breaker plates to eliminate the vacuum can.

I don't know if lean burn parts will work. Not only do they not have vacuum advance, they don't have mechanical, either.

If you remove the vacuum, you'll have to take steps to stabilize the advance plate, as the vacuum can helps hold things in place

You'd have to check "rotor phasing." Just Google this, lots of info. You will want to check that the rotor is centered on the cap tower contact "when the spark happens" by using a junk cap with a hole in, and a timing light.

 

[Larry Hubert]

If the vacuum advance is in the way of the distributor hold-down bolt, there are two simple solutions: (1) buy the correct offset distributor tool from KD or (2) rotate the distributor 180 degrees and insert the wires in the correct holes.

 

[604]

I have always read and been told that the vacuum advance dose absolutely nothing at full throttle. That it only works at part throttle when you have vacuum. It's purpose is to improve mileage at part throttle.

I set the total timing at 36' and it runs ten times better with the advance plugged, as I could not adjust the advance down to 50' The lowest I could get it was 56' and it sputtered at that amount.

I took out my vacuum advance and put in an MSD Pro Billet dizzy and a Mopar Performance MSD-6 box. Pretty nice way to go. If you aren't using the vacuum advance, you aren't getting the most out of your motor. You can certainly find distributors with mechanical advance instead. You need that advance at higher rpms.

 

[RedFish]

There is a hack job method that deletes the vacuum canister A limb is still attached to the advance plate but it ends at a home made bracket with a thumb screw. You can adjust the timing slightly there.

 

[604]

Thanks,
I may just leave it on there and find a wrench tat gets down there a little easier. I did find Mopar makes a Pro billet dist with no advance, but they are prod of it! LOL

http://www.summitracing.com/parts/DCC-5249776/

 

[oldkimmer]

............u can get a lean burn dist and swap over the pieces...........kim.........

 

[72bluNblu]

If you aren't using the vacuum advance, you aren't getting the most out of your motor. You can certainly find distributors with mechanical advance instead. You need that advance at higher rpms.

It really depends on how the timing is set. My car runs best at idle with 18* of timing, so, even with the vacuum advance adjusted to its absolute minimum I was getting over 50* of advance all in, which is way too much and caused detonation. With the initial at 18*, the mechanical set up for 36* of total advance and the vacuum advance unhooked my car runs MUCH better than it ever did with the vacuum advance hooked up. 36* is plenty of advance. So, the idea that not using vacuum advance means you're not getting the most out of your engine isn't accurate at all. You just need to make sure that the distributor is set up to give you the advance that you need.

 

[604]

Your engine sounds just like mine. I am between 18 and 20 initial, and about 35 or 36 total with the vacuum plugged. With the vacuum hooked up it was over 50 and not sounding to good. Sure runs great now with it plugged!

It really depends on how the timing is set. My car runs best at idle with 18* of timing, so, even with the vacuum advance adjusted to its absolute minimum I was getting over 50* of advance all in, which is way too much and caused detonation. With the initial at 18*, the mechanical set up for 36* of total advance and the vacuum advance unhooked my car runs MUCH better than it ever did with the vacuum advance hooked up. 36* is plenty of advance. So, the idea that not using vacuum advance means you're not getting the most out of your engine isn't accurate at all. You just need to make sure that the distributor is set up to give you the advance that you need.

 

[Mopar to ya]

It really depends on how the timing is set. My car runs best at idle with 18* of timing, so, even with the vacuum advance adjusted to its absolute minimum I was getting over 50* of advance all in, which is way too much and caused detonation. With the initial at 18*, the mechanical set up for 36* of total advance and the vacuum advance unhooked my car runs MUCH better than it ever did with the vacuum advance hooked up. 36* is plenty of advance. So, the idea that not using vacuum advance means you're not getting the most out of your engine isn't accurate at all. You just need to make sure that the distributor is set up to give you the advance that you need.

So they just put a vacuum advance on to create problems? A correctly working vacuum advance does what it is designed to do - give you proper advanced timing at higher engine rpms. However, most of these distributors are 35 - 40 years old and have never been touched. If your advance is opening that much, there are issues with the distributor or advance. Plus, most run a stock distributor and vacuum advance on motors with cams, custom exhaust, intakes and carbs - all of which change the dynamics of the motor. My statement is not accurate? That is not true at all. I personally run a mechanical advanced distributor and don't have those issues, but springs get week and weights pull too far with age.

 

[airgrabber]

Is it possible to remove for good the vacuum advance canister from a new MP distributor? I do not use it. And the darn thing makes it a royal pain to get to the hold down bolt. Would be nice to just have it gone. If not is there a plug and play distributor with out one that works with the Mopar electronic set up??? Thanks!!

You can remove it. Need to mark the position of the plate at idle and either braze,JB weld or some other method to keep the advance plate locked down.
But it sounds to me like you need to tune the total amount of vacuum advance you are getting. If you are at all interested in fuel economy, even with your hot rod, it might pay to experiment with different vac advance diaphragms. I believe they are stamped on the arm to indicate different amounts of travel, and therefore different amounts of advance they provide. Or else find a way to limit or tune the total amount of travel in the vac advance diaphragm arm or the plate itself so you can increase or reduce the total advance added by the diaphragm.
You can also change the rate at which the diaphragm opens by means of an allen key inside the vac hose stem. There's a set screw inside the diaphragm to increase or decrease the tension on the diaphragm spring. Sort of like putting a heavier or lighter spring in a Holley vacuum secondary diaphragm

 

[72bluNblu]

So they just put a vacuum advance on to create problems? A correctly working vacuum advance does what it is designed to do - give you proper advanced timing at higher engine rpms. However, most of these distributors are 35 - 40 years old and have never been touched. If your advance is opening that much, there are issues with the distributor or advance. Plus, most run a stock distributor and vacuum advance on motors with cams, custom exhaust, intakes and carbs - all of which change the dynamics of the motor. My statement is not accurate? That is not true at all. I personally run a mechanical advanced distributor and don't have those issues, but springs get week and weights pull too far with age.

Look, my point is that you can have a perfectly functioning engine WITHOUT vacuum advance, even with a distributor that was designed for it. You can actually have a better running engine without it, depending on how your timing is set. It absolutely depends on your engines timing, you can't make a blanket statement that if you're not using vacuum advance you're leaving power on the table.

The vacuum advance works great and gives you the proper amount of advance if you're running the specified amount of initial advance. But if you look that up, the tune up specifications for most SBM's call for less than 10* of initial advance. Some of them, depending on the year, call for 0* - timing set right at TDC.

I'll use my 318 as an example. My 318 doesn't even RUN at 0*. At 12* advanced it starts to run ok, and it's happy at 18* advance. That means that with the vacuum advance hooked up and running properly, I'm running over 50* of advance all in. That flat doesn't work, even with the distributor and advance all working as it should. In order to keep from detonating, I had to run about 10* advance, and my engine HATED it. Unhook the vacuum advance, dial up the initial timing, and viola, car ran like a champ.

If you assume less than 10* of initial advance, like the factory did, you'll see that with the vacuum advance hooked up and the timing set as specified you'd be looking at the upper 30's for total advance, maybe low forties. Not mid to upper 50's. If you run 18* initial, you can't use the stock vacuum advance. Plain and simple. But, you can STILL get the proper amount of advance needed for the engine.

I've seen more than a few SBM's with really high initial timing settings like mine. Not sure why, until I had my 318 (which is almost entirely stock, BTW) I'd never run that much on anything. And if that is what you need to run for initial, you do need to rework your timing curve, because not even the stock mechanical advance will be right on at that point. I now run a pertronix billet distributor, vacuum advance unhooked, and mechanical curved and set for about 36* all in. And that 318 runs great just like that.

 

[jos51700]

The only reason you have to get rid of vacuum advance is to satisfy ignorance. You can have a vacuum advance canister, hooked up and functional, on any vehicle, race or street, with nothing to lose. In fact, on your street car, your motor will live longer and you'll get better fuel economy.

Fact is, at WOT, vacuum advance does nothing. Zip. Zilch. No vacuum (as in, at WOT), no advance. End of story.

At cruise (no matter how bad *** you think you are, if it's on the street, you're in "cruise" mode most of the time), you get a cleaner more efficient burn which means your rings live longer (less fuel wash) and better mileage. It's there for a reason! You like how the EFI motors live forever without needing ring jobs at 100,000 miles? That's due in large part to reduced fuel wash. Seriously. Look it up.

If your motor doesn't run well at cruise when you set your timing to whatever mark on the distributor, you need to tune your distributor, just like you would anything else on your car. Advance springs and a twist o' dist aren't all, you can control the amount of total advance by swapping advance canisters, and the rate of advance by an allen wrench in the vacuum nipple.

So, it does NOTHING at WOT so it won't hurt your performance, and it helps your motor live longer and make more response and economy at cruise. Reason to toss it? NONE.

If you insist on removing it, I'll pay for you to ship it to me! Just unscrew all the screws in the trigger plate, lift the plate up to unhook the arm, and unscrew the advance canister. Presto change-o! I keep a myriad of vac-advance cans around to tune with, and can always use more.

If you've seen the light, there's an issue of Mopar Action from '99 (I think it has a silver 300C looking droptop on the cover) that covers it all.

And yes, there is NO advance in a lean burn distributor. If you want to be super trick, you can hunt down (or buy at Autozone) the dual trigger plate. Flip a switch for bad fuel/race fuel, tow, or nitrous modes!

The main upshot of expensive distributors is ease of tune-ability. Your factory Mopar distributor has all the same functions, they're just not as easily accessible!

 

[jos51700]

And you can run advance well beyond 50 degrees if the rest of the curve is set properly.

 

[67Dart273]

The only reason you have to get rid of vacuum advance is to satisfy ignorance. !

NOT true. Most of what you posted is correct FOR STREET cars, but the OP did not say. For track use, or even a hot street / strip car that is "only" street driven occasionally, there might be a good reason to remove vacuum advance........

TIMING ACCURACY. Many factory distributors don't hold timing accurately BECAUSE of the advance plate wandering around "in there."

For some of these guys, who aren't "street cruisers" vacuum advance is not relevant.

 

[805moparkid]

And you can run advance well beyond 50 degrees if the rest of the curve is set properly.

maybe on good gas but 35 is the most i can get out of it before it pings on 10:1 with 30 all in after start up...

 

[jos51700]

NOT true. Most of what you posted is correct FOR STREET cars, but the OP did not say. For track use, or even a hot street / strip car that is "only" street driven occasionally, there might be a good reason to remove vacuum advance........

TIMING ACCURACY. Many factory distributors don't hold timing accurately BECAUSE of the advance plate wandering around "in there."

For some of these guys, who aren't "street cruisers" vacuum advance is not relevant.

Is it necessary on a race car? No, as mentioned.

If there is "wander" involved...removing the advance plate has nothing to do with it. Any wander is characteristic of worn/poorly maintained parts and not related to the VA components.

 

[67Dart273]

Is it necessary on a race car? No, as mentioned.

If there is "wander" involved...removing the advance plate has nothing to do with it. Any wander is characteristic of worn/poorly maintained parts and not related to the VA components.

Sorry, you don't know what you are talking about. Poor timing accuracy in factory Mopar distributors is a WELL documented problem and has been since before I owned my first RR in 1970. There has been COUNTLESS articles in magazines for the last 40 years about problems with these distributors. "Wear" certainly is an issue, but the problem goes much much deeper than that, and yes, I'll say it................

poor design on Chrysler's part

Back in my "440" days, I was lucky enough to score a used Mopar hemi dual point dist. with a tach drive

THE IMPORTANT THING about a tach drive Mopar dual point is that IT HAS A BALL BEARING top bearing!!! AND unlike the factory single point dist -- of which the factory breakerless is merely an outgrowth-- the dual point dist's have a BALL BEARING pivot in the advance plate, a MUCH more stable design that the single point/ breakerless advance plate.

 

[604]

My oh my what a can of worms I have opened! LOL

First off,
My car gets driven a max distance of maybe 15 to 20 miles at a time. For a total of 200 to 300 miles a year. Probably more of the time with the pedal pushed to the carpet than in cruse. This car is not a cruiser. It is going to be more of a race car than at rood trip car. Just drove it on a 20mile trip to a car show yesterday, and it ran better than ever with the canister in hooked. Yes I know how they work, and what they do.

Second my distributer is new, and has the adjustable advance. The adjustment dose nothing. I have tried. From screw all the way in to all the way out.

Third I would play with deferent canisters if I new were to get them. I have looked and looked and all I have found is stock Mopar replacements

And I even noticed with a timing light that my timing is rock steady at 3,000 with the advance un hooked. Hook up the advance and not only dose it go to high, it wonders all over the place. OK that may be a exaggeration, but you can see it move around some what.

Thanks to everyone for the input!

 

[bobscuda67]

If the canister position is the problem just rotate the oil pump drive to get the canister out of the way.
If your car is street driven at all, it will run better with a properly set vacuum advance dist.

 

[805moparkid]

Is it necessary on a race car? No, as mentioned.

If there is "wander" involved...removing the advance plate has nothing to do with it. Any wander is characteristic of worn/poorly maintained parts and not related to the VA components.

ok we all agree that mech advance just advances the rotor... but when the plate moves, as when vac adv kicks in/out the whole pickup moves, or changes phase, thats where the "wandering" comes in...

 

[604]

Well I went out this morning to give it one more try. Here is what I found

I gave up on the vacuum advance adjustment after 1/2 hour of not able to get the allen wrench to go in the screw and pulled the distributor again.

The factory MP canister is junk. Pure and simple. I think aluminum foil has a better resistance to bending. You can bend it all over the place with extremely light pressure. This in-turn moves the pick up plate. So any engine with a decent cam that shakes is moving the timing all over, to a degree.

The pick up plate fits loose as a goose to the distributor plate. I can move the pick up closer of further away to the reluctor with very little finger pressure.

The reluctor looks like it was thrown out of a moving car, and skipped down the road. Lots of nicks and dinged up edges.

What I did.

Totally disassembled the top half of the new distributor. I then disassembled my lean burn unit I had laying around. I installed the lean burn pick up and plate in the new distributor. Screws in nice and rigid to the housing. No slop or play of any kind. I installed the lean burn reluctor, as it was perfect, not a nick on it any were (really shows the deference from back when they cared about quality!) I threw the new reluctor in the round file LOL. I then set the gap to .oo8 Installed the nice little cover to block off were the canister would have been. And done.

I installed it on the car. Timed it to 35' total, which gave me about 18' to 19' at 700rpm. And it runs great. The timing no longer has one ounce of wander to it. Rock steady. Just proves that all that slop in the top end of the distributor was to blame for my miner float in my timing.

As for the little bit of extra mileage I am loosing with out the vacuum, I could not care less. If it washes a little bit of oil of the cylinders I do not care. This engine will probably not even see 5,000mi in it's life time. Heck maybe 1 to 2 K. As soo as I can aford it I will be starting on a bigger small block. All I care about is how it runs with the pedal mashed to the floor.

 

[67Dart273]

Good job. Only one more thing you want to check. ROTOR PHASING You can google this, but essentially you take an old cap and cut/ drill the cap so you can see the rotor near the no1 plug tower.

Just run the engine with a timing light and play with the throttle to change the advance. The rotor should "make spark" withing the "envelope" of where the rotor end contact is brushing past the tower contact. The "perfect" setup for no vacuum would be when the spark fires and the rotor and tower contacts are CENTERED with very little movement

(Vacuum advance changes rotor phasing, mechanical should NOT)