1968 Dual Vac Advance Issues

[Anonymous]

Is the '68 200 distributor and/or vacuum advance the same for both the manual and automatic cars? (dual vacuum).

According to the shop manual, the dual vacuum advance is different for autos and manual trannys.

Yet, when I go to find a new distributor, suppliers make no distinction for autos or manuals.

I bought a rebuilt distributor and the advance appears too slow causing the car to sputter and bog.

Any ideas?

 

[simon]

According to the shop manual, the dual vacuum advance is different for autos and manual trannys.

Yet, when I go to find a new distributor, suppliers make no distinction for autos or manuals.

I bought a rebuilt distributor and the advance appears too slow causing the car to sputter and bog.

Any ideas?

MontegoMan:

My manuals lists 48 different ford dual adv. distributor applications for 1968. To find a setting you can start with, the original number would be helpful (yet not absolutely necessary)

The mechanical advance can be tuned to kick in earlier. Get yourself a "ford distributor spring kit" such as manufactured by the "mr.gasket" company, or rob some from the junkyard. Remove the breaker plate/ stationary sub plate assembly to gain access to the centrifugal advance assembly underneath.
Swap the stock springs for the lighter springs that come with the kit and see how she runs.

personally, I wouldn´t hook up the retard side of the canister, unless I´d be dead serious about a 100% correct restoration or experiencing hot running problems due to those emissions voodoo gizmos.

 

[Anonymous]

So should I consider switching to a single vacuum (advance only) set-up?

No emissions gizmos here!

 

[simon]

more or less a matter of taste. both can be set up to perform about the same, but the dual vac canister will always look bulkier and cost more on the counter.

Unless you want a stealth OEM look on your engine (if it came with dual vac originally), I´d take the single vac canister dizzy for its simplicity and cleanliness (no unused port that might catch the judge´s eye)

 

[Anonymous]

I'm shooting for the stock look and simply reliable, smooth performance.

I bought a rebuilt dizzy from a parts store and I can't get the the advance right. I have swapped lighter springs, but I noticed that the AUTOMATICS had a whole different curve than the MANUALS, yet in every parts catalogue and parts store, they make no distinction between the MANUAL/AUTOS.

So, I am assuming the vacuum advance is incorrectly set on that distributor.

What am I missing here?

 

[simon]

So, I am assuming the vacuum advance is incorrectly set on that distributor.

you´ll want the centrifugals to full advance around 2000-2300 rpm. if they are fully advanced significantly earlier, swap one of the springs back to the lightest original spring

Have you set the distributor with the vacuum disconnected, how much initial advance, and how did it idle and rev?
With the vacuum advance connected, what exactly are your problems?

 

[Anonymous]

I bought a rebuilt unit from Autozone for a '68 and installed in my '66. I think the rebuilt unit is probably set up at a more conservative timing map. I'll have to dig out some notes, but the advance curve was pretty sluggish and did not advance very much. You can adjust spring tension by bending the metal tab retaining the springs. The procedure is outlined in the shop manual. You have to line up the hole in the distributor base plate with the spring tab and insert a screwdriver to bend the tab in our out.
Doug

 

[simon]

...did not advance very much.

if the overall amount of centrifugal advance is too low, the cam assembly can be turned 180° to make use of the larger advance control slot. The numbers stamped on the cam arms show half the advance degrees that can be achieved by using each slot.

Anyhow, we need to know what exactly is wrong to give good advise.

 

[Anonymous]

I do not know for certain, but I am just thinking it is in the rebuilders interest to rebuild to conservative OEM specs. The market on these 40 year old cars is not that great, thus the consolidation of all the advance curves into one curve. Also if a distributor is installed that has significant advance, and the engine is destroyed through detonation, the rebuilder could be found liable for damaging the engine. So, if you are looking for any performance from the rebuilt distributor, it will surely require custom tuning. The average customer will get a trouble free replacement, but lackluster performance if it is just dropped in as a replacement and the initial timing is set to factory specs.
Doug

 

[Anonymous]

I will try to be as clear as possible in my description:

Engine: '68 STOCK 200 w/ 3.03 manual trans on the column in a '68 Montego (intermediate).

Carb: REBUILT Autolite 1100 1V. The idle is good; mix is good. No smoke at idle or during crusing speed. Vacuum appears normal at idle: weak from the carb (advance); Strong from the manifold (retard). At high RPM the carb vacuum increases.

Distributor: Right now it is a rebuilt unit from PartsAmerica with dual vac advance. I have the car timed at 10 BTDC (6 is stock setting). Standard points/condensor set up for now.



Symptoms:

At idle, there is no difference in engine response when the vac lines are connected or disconnected.

During acceleration, the car will sputter and put out black smoke; there is a loss of power.

Then, as the RPMS increase, all of a sudden the sputtering stops and the car feels like it has power once again and takes off. It always happens during initial acceleration.

According to the '68 Shop Manual, there is a different curve for each engine and for each transmission type. Yet, there is no parts source that differentiates anymore. As soon as I put the distributor on, it did this. I have changed the springs, but that didn't help all the much.

I am not looking for a HUGE performance boost, I just want to get rid of the bog and run smooth for cruising with the best possible performance out of the set up.

All the help and suggestions are appreciated!

Jay

 

[pedal2themetal45]

HI
Just a thought have you tryed reversing the vacuum lines to the dizzy? Sence it started with the instaltion of the dizzy.

 

[simon]

Jay;

I´d suggest unplugging all of the vacuum lines first. Set the distributor on the desired initial advance. Then, simulate the worst case for any engine: take the car for a test drive, put her in highest gear at low speed and nail the throttle. Advance as far as possible until she starts pinging, then back off a hair until you won´t hear any detonation while flat footing in third at low, low speed. Check with a timing light now, should read something around 15-17°.

next, connect the advance side of the vacuum canister with straight manifold vacuum. This will permit advance at idle, which will slowly decrease during acceleration until your centrifugal advance speeds up to full advance. Leave the retard side of the vacuum canister alone (for looks, attach a plugged vacuum hose).

 

[Anonymous]

Jay, I think you might have a fuel mixture/jetting issue that is giving you the bog and black smoke in addition to the timing issue. The Autolite 1100 is a ported vac carb, so at idle, you won't see much vacuum or vac advance. As Simon noted, I would hook up the advancing port of the distributor's vacuum diaphram to manifold vacuum. You should see some sort of change in the idle speed. And you should see the timing mark advance significantly at idle when hooked up to manifold vac. If nothing happens when hooked to manifold vacuum, check to see that the vacuum advance mechanism & linkage in the distributor is free and not binding. It could be possible that the diaphram is bad.

I would also check to see that you do not have a spark control valve from an older carb on your carb.
Doug

 

[FrankBoss]

Not to change the advice posted but I know that most ford mechanics in the early 70's would put BB's or ball bearings in the manifold line to block this port to reduce the bog in town driving.... in doing this they would pass the visual inspection at the emissions test....

Best of luck
Frank

 

[Anonymous]

All good advice and please keep it coming!

We did swap the vac lines. At idle, there was only a little change in the RPM. Under load, the car had more power (w/ the manifold line attached to the advance port), but it still sputtered and smoked, during acceleration, albeit for a much shorter period of time. Thus, we figured it must be the advance because it appeared the spark advanced faster with the stronger vac pushing it at first until the centerf. took over.

The spring in the diaphragm is much more tense than the original. I put the original spring back in and noticed only a slight change as well.

I am 99.9% sure the carb does not have a spark control valve, but I will check to be sure. When I got the car, it had an 1100 set up for an AUTO on it. I have since changed the whole carb.

Before I rebuilt the carb, the sputtering was REALLY bad and really put out smoke. During the rebuild, the float was horribly off.

Since the rebuild, the smoke has decreased by about 75% and now it only bogs and smokes during acceleration. If I slowly accelerate there is no bog, no smoke. It only bogs and smokes during normal acceleration, which I would guess tells me it is not advancing fast enough, or there is too much vac/tension on the retard side.

So, I am inclined just to buy a new distributor and start over...I just want to be sure I am getting the right VAC set up...

 

[Anonymous]

I do not recall on the vac motor with advance and retard nipples. Is it possible to access the diaphram spring and adjust the tension using a hex key inserted in the nipple? I would think it may be adjustable via the advance nipple. You might try loosening the tension to see if you get more vacuum advance action from the distributor.
Doug

 

[Anonymous]

Doug,

That's where I think my problem lies, or at least I want to confirm that it isn't.

On the vac diaphragm, there is a bolt which comes off and exposes the spring and plastic "stop." There are also washers in there too.

What is a hex key? Is that how the vac advance can be adjusted?

As you or someone suggested earlier, I think the VAC advance is just fouled up and I am hoping when I put a new one on, the situation is resolved. But, before I do that I want to see if:

1) I can correct the situation w/o buying new

2) Buy the right distribuutor/advance.

 

[Anonymous]

Sounds like you have an old OEM style vac cannister. I think the shop manual has a section on adjusting the tension by removing or inserting washers in the vac cannister. I have not done that adjustment procedure, because my vac cannister was not holding vacuum, so I just ended up replacing and upgrading my Loadamatic distributro with alater model that happened to have the different style of cannister. On many newer and replacement vac advance diaphram cannisters, you can insert a hex key into the nipple and adjust a screw that varies the spring tension.

 

[Anonymous]

An update:

Doug, you were right, I do have a SCV on the carb. I went back to my original pics when I bought the car, and my memories came back. There was no SCV until I ordered a rebuilt unit which came with the SCV. When I rebuilt that carb this spring, I just threw the SCV in there until I read what David posted in another thread. I was under the impression I was getting the EXACT replacement parts I needed. Lesson learned!

So, today I got my rebuilt distributor delivered and IT IS A SINGLE VAC ADVANCE! (I oredered a dual vac advance distributor, per the '68 OE spec).

So, I think I am going to try the advice you guys gave me by only hooking up the advance side of the cannister to either carb vac or manifold vac and see what happens.

If that doesn't stop the sputter, I am then going to try to plug the SCV port and passages with epoxy.

I also bought a spring kit from Mr. Gasket as well.

I'll report back!

Jay

 

[Anonymous]

Dumb question here...

I got a 68 engine in a 66 convertible. Has advance/retard distributor, and mechanical advance, I believe.

My carb is a rebuilt 1100 with an SCV.

Do I need the SCV? If not, can I remove it and plug it somehow?