You can get most any vacuum control units from parts stores such as O'Reily's (where I got mine) They can look them up in a paper catalog and you can see all specs and a picture. Many to choose from: some are adjustable, some are not. You just have to decide on what you want....only downside is they are pricey: anywhere from $15-$23...but they're new, not remanufactured, so you get what you pay for.......I had two reman'd distributors with reman'd pods and they both leaked, not to mention the cam was loose on the yoke! Absolute junk these days, I've been to a couple of distributor, alternator, starter rebuild facilities on business and what I saw was very discouraging.........suspect workers, suspect conditions and cheap replacement pieces.......Figures.....But I got things fixed right in the end

InThePink,

I really like the 11R vacuum pods, a VC-208 is an example of one, $9.95 @ RockAuto.com.

I have adjusted mine to 4 turns out (in other words its off) to give good steady initial and mechanical advance only in the low to midrange. To explain, I first get the 30 degrees (initial plus mechanical) then the pod kicks in, giving you the nice bottom end with out pinging and then it comes in like overdrive after 2000 rpm and gives you allot of advance and great mileage.

Set up this way you get good drive-ability and power when you need it. Sort of like a drag race setup with the frosting on top. You will find the vacuum gage is rock steady and doesn't jump all over the place like when the pod kicks in too soon. I find that when it kicks in too soon it is way too sensitive to throttle changes...you may need to go 4 to 5 turns out to settle it down. Mileage will go way up because you will be staying out of the power valve allot more at or before cruise.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Since I've never dabbled in vac advance pods, what exactly are you turning out 4x?
That's sounds like what I'm after.
Hmmm, sounding good to me...

I removed the dist tonight and is was a little crusty around the dist base o-ring gasket, so the o-ring will get replaced, but everything else was in good shape. Anybody know off-hand what the diameter and thickness of said o-ring is?

FWIW, I'm running an A-833 O.D. trans behind my slant.

Thanks for the advice.. Keep it coming, please.

Casey

Casey,

As you can see below my signature it is a 74 Dart Swinger SL6 rebuilt and highly modified for torque with a 904 etc....it's a tire burner even with the posi.

Send me your email I will send you Doctor Dodges article on how to recurve a distributor and how to set the distributor pod.

In short you take a 3/32" allen wrench and put it in the snout to engage the adjustment screw. It has a 3/32 allen head inside. Turning it out will delay when the pod kicks in......do a search and you will see a matrix on a VC-208, what one turn, 2 turns, etc....will give you.

Don't know the diameter of the "O" ring but you can buy a larger one and cut it too length and re-glue with super glue. I have done it for about 20 years now....

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ah, gotcha. I thought I was missing something.

PM sent.

Casey

Ok Casey, just sent you a boat load of info.....plus the .jpg How to manual.

You can buy an "O ring kit complete with glue at some stores.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

They are available at any autoparts store under distributor parts for a 225-1v 1974 Valiant... $3 or so.... if you buy a full gasket kit if you rebuild your slant they are also included there too...gluing sound like an oil leak ready to happen....

Be careful on recurving... 'ping' is only the sounds of trouble and detonation... if you are 'close' but still over advanced a few degrees... you are looking at problems later, but you won't hear it until something gives...
(it can be your valves)




-D.Idiot

Casey,

First, lemme caution you that recurving is one of those things you have to do.....and do and do and do until you get it right. I LOVE doing it, but I believe it is like not being a "little pregnant"; in other words if you jump in you can't just dabble because you have to systematically change things with a planin mind, keep good notes and over time you get it. I am saying this because your queston seemed to me more of making some tweaks to keep on running a stock daily driver than wanting to really do recurving. (Hey, that is where the addiction starts!) In such a case (where we all were once) I suggest if what I had was a bad vacuum can, THAT is what I would fix. alone and see what happened then. Your succcess there will give you courage for the next step into recurving.

When picking a replacement can, immediately you are faced with the next question set of "which can do I want?" That is why I posted the range of vacuum all the common cans come in at with various turns out. You will see you can actually adjust the common cans so about all them will be working similarly to one another at some point.

Then the next question set is "what range do I want the advance coming in over?" Answering that question requires some experience in how YOUR combination is performing, so you will have to understand how each spring change or governor change may affect your result. Because there are 4 to 6 major parts to play with in recurving, you can get a similar result from several directions. Remember the old probability question: "How many combinations are possible from 6 things taken 2 at a time?" This probabilistic puzzle solution is why I LOVE recurving.

I am doing a nearly 4000 lb torque monster truck that basically is designed to live below 4000 rpm. Very different from Ted's lighter car yet he and I both want the same thing. (I think) For me I want kick-a.. acceleration and power to start, also even, no miss acceleration and a smooth change through all gears until whatever I want to peak out at, be it 6,000 or 4,500 instead of the usual 3,500.

When I got started Rob, (DI) encouraged me in the wisdom of getting a small collection of dizzies with a range of cans to strip parts from for experimenting. Realize you can use springs from points dizzies and the points ones are often only $5 or free. They are good carcasses for O-rings, the little felt pad on the top under the rotor, the little spring under that pad, and so on. Plus you can tear em down and learn how the EI ones work before you tear into an EI one. I added EI for a betetr spark, see it never stops). You should have at least 2 dizzies, one to run and one to tweak.

Where I am going is you can use ANY can from an old EI dizzy to start your learning, don't get wed to a vc 208 yet. So long as the call will pull when you put a vac to it, it will likely be adjustable for your use. I am wavering right now between a vc 208 (11) and a 9. I don't think the ranges of the common 6.5 and 7 cans are what I need.

I can't help but smile at seeing a fellow slanter at the edge of the recurving cliff ready to jump...but put on a working can first.

rock
'64d100

I understand it's not an exact science and requires tuning and testing to find the right combo for my setup, so that's not a problem. Just waiting for the parts to arrive to get it up and running again...

Rock,

Yes, I like loads of torque right off idle and the six likes it as long as you don't exceed much over 30 degrees.

I am at 32 degrees @ 2500 rpm, 16 initial and 16 mechanical. 30 degrees @ 2000 rpm which is 50 mph with tall 2.76 gears. Tall gears act like a heavy load. My Dart with a full tank another person, dog, etc. weighs in over 3600 lbs. I still have the big heavy bumpers and rubber bumper guards on mine. So it sees a good load and I want the kick in the pants punch, which SL6 is very capable of. Lots of SL6's I hear, have too light of springs and they just rev, no punch, just wine. 60' times really suffer.

You could go 10 initial and 20 mechanical or any combination you want being limited by the springs and governors your able to find.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Ok, so I installed a new o-ring, distributor drive gear (old one was brittle) and the VC 208 can (turned out about 1 full turn, as it came in the box).

There is definitely more pep at light throttle (say 20-25%), so that's a good thing.

Here's the problem- at WOT, the engine stumbles and coughs. My initial timing is at 12 degrees, but I think it could handle more. I need to rotate the shaft a bit as I'm maxed out on the adjusting bolt slot, but if I understand correctly, there is no vacuum advance at WOT, with the mechanical (springs and governors) and initial timing (12* as it sits now) providing the advance at WOT. Is that correct?

With my standard timing light hooked up correctly, should I be able to see a few degrees change in the timing (vie the crank pulley notches) when under 20-25% (light) throttle? As of now, under WOT, there is little change in the timing when using the timing light to check.

I'm slowly understanding this, but it's gonna take some more advice and comments from more experienced tuners, so keep the advice coming.

Yes, initial plus mechanical is all you get with the pod unplugged which would simulate WOT.

Hopefully your not revving it too hard, WOT!!! Running rough with no load can be many other things, like carboned up plugs and heads, poor spark plug wires, poor coil, poor voltage, point bounce, poor fuel distribution, etc......

Your vacuum pod is out of the loop at WOT and or at low vacuum. You should see 30 degrees with the timing light by about 2500 rpm.

Let's use 2500 rpm as a reference, since it shouldn't do any damage while testing and tuning.

If your at 12 degrees initial you should see with the timing light another 18 degrees of mechanical kick in at 2500 rpm. It will run off the timing tab about 2". One way to verify this is by using a dial back timing light. Another way is to file a notch or paint a line on the damper/harmonic balancer every 10 degrees.

If your not getting atleast 30 degrees with the pod unplugged, then something is wrong with the mechanical advance. Maybe the grease is stiff and it is not letting the weights swing out or something broken and jammed inside limiting them or in my case someone had installed super heavy springs on both sides so it was only advancing 10 degrees max by 2500 rpm.

_________________
Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

The other thing you need is a vaccuum gauge as well as a tachometer...'

You need to map a few 'points' to maximize your effort... things to note are rpm and vacc. at idle, off idle, 'cruise' in the city, cruise on the highway, and WOT....

You will be suprised that sometimes at WOT depending on the build WOT may not be '0' on the Vacc. gauge... if you are under carburated you will have something like 3-5" on the gauge....

If you take the time to 'map' your mech curve (run the throttle up and plot the advance from idle to just above your cruise/highway rpm)... then set the idle screw to about 1500, zero the timing light and use a vacc. hand pump to see the vacc. advance come in and how much at 0-20"

you can tell relatively how much timing you have when driving...

The stock springs don't allow much advance (they are very restrictive and you won't see too much advance between idle and 3000 rpm mech wise.. so the vacc. advance has to help out... a spring change will help that a bit... but you have to check things again then take a test drive...)

also all things are interrelated... so if you change your timing, you will also have to redial in the settings on your carburator (timing tells you when the fire is lit in the cylinder... the carb has to make sure there is enough fuel to make a complete burn across the piston face and bore...)
Also, there is no one real 'catchall' recipe for a perfect curve... your car loaded weight, engine build, carburation, tranny choice, rear axle ratio, driving style, driving terrain, and weather can all play a part in determining the 'better' settings for your vehicle...

Good luck on your tests,


-D.Idiot

After playing around a bit more and rotating the dist 'til it hits the end of the slot (it was not against the stop as previously thought, I do now have about 30* initial + mechanical and the engine performs much better at WOT just a slight hint of stumble.

The carb was rebuilt a few months ago and there are no leaks. I don't doubt the carb will need some tweaking as it was never perfect, but it was pretty close. I've been adjusting the idle screws and idle speed screws as I adjusted the timing, so I have a good, mostly consistent idle. Yeah, I do need to add a tach, but I'm reluctant to hack up the dash or add an obvious aftermarket tach. Maybe for now I'll just use the Autometer tach I have for tuning purposes...

The fuel pump is new and is working fine and there are two new fuel filters installed, so I'm pretty confident the fuel supply to the carb is good.

Since I went from an A-904 auto to an A-833 4-speed, there is some newness (in terms of seat of the pants feel) to adjust for, too.

I am going to try advancing the initial timing a little bit more by moving the dist drive gear over one tooth (since it's maxed out against the slot) and seeing if that helps any at WOT. It's pretty close, but I'd like to see if I can get the initial timing close to ideal before I possibly delve into the mechanical advance springs.

I'm making progress, so that's what counts. Thanks for the comments and advice so far.

Casey

Err... that will be over-advanced ... if you need more... run the engine up to #1 TDC for easy measuring.. pull the dizzy and adjust the slot and other bolt on the bottom of the dizzy body... that's good for a few more degrees... (for easy advancing... find a 1979+ slant car or truck and steal the dizzy plate and hold down fork from that... no more 'slot' to worry about....)

'Pause' in the acc. curve is due to a lean out... either due to timing being off.. but more likely, your carb's acc. pump shot isn't timed right (adjust linkage...), to cover the quick opening of the throttle plates, and the quick load up of dumping the clutch...


-D.Idiot