Its a magical bond between Man and MACHINE

Thank you so much OP, I,ve been working on engines like yours most my life and have learned many tips and tricks over the years from people wiser than myself like you. Very much appreciated because like you said they are all different and need fine tuning, this is a great way to do that.

Good stuff, Andy! Being drag only, I don’t expect to run vacuum advance on the 73, but I want to do exactly this procedure on my 70 Dart. Thanks for the great info!

Most cool. I have a hand vacuum pump and all kinds of vacuum gauges and never thought about doing this. This is a huge part of how you dialed in your tune to get such efficiency.

Well hell, now I don't know what my motor wants and I don't know what I want, we need a part three in detail

Something you should also note on your next video is some adjustable vacuum cans adjust rate at which the advance comes in and then there are the cans that adjust the total amount of time the vacuum advance will add. Mine was the rate and gave 20° advance no matter how much I adjusted it. So may be something you want to let your viewers know. Once again great video.

I locked the timing out on my 347 and honestly it did pretty good for fuel economy. It has 11-1 with a 236-243@50 roller cam. I might just try a vacuum advance and see when I get it back together.

Thanks Andy another video full of relevant and descriptive facts.

Found you through UTG, Tony's awsome, but I'm a Ford guy, and even better I'm a Ford truck guy 👍 My first hot rod was a 79 dentside with a pump gas 460, great truck. Subbed for Casper and the Mixed up Boss!

This video was full of information that is so useful,andy you know I’m a fuel injection guy but my buddy has a SB 400 Chevy that is very close to the setup you have/had on Casper I can’t wait to try this and I will let ya know how we make out because the weak point of his set up is driveability. Thanks for another great video.

This is what I got from the DV video on setting ignition timing. Idle timing Mixture first Connect vacuum gauge to manifold. Disconnect distributor vacuum advance and plug. (Or connect to vacuum gauge. ) Set throttle screw little higher than normal. Adjust idle air screws in until engine starts to slight stumble. Adjust idle screws and throttle screws until vacuum is the most minimal vacuum. This means your engine is idling on the least amount of possible fuel. At this stage you start advancing the ignition until the idle is steady. (adjust ignition timing at the distributor until the idle is steady) Readjust idle air mixture if necessary. (Mixture at idle takes precedence over timing. ) Adjust ignition timing until you get the best vacuum reading. Idle mixture should be around 15 to 16 to 1 fuel air ratio. And advancing or retarding ignition to set at what it runs best at with best vacuum. Recap; Adjust idle mixture by leaning it out as much as possible. Consistent with getting the lowest vacuums possible. At this point start adjusting the timing until you get the most vacuum and highest rpm. Repeat until you have the best idle. Then adjust down the idle speed with the idle screw. Continue this procedure until the engine idles like your grandads pocket watch. At this point you should have a good idea of what the vacuum is at idle. Check and note timing. Connect up the vacuum can. And with vacuum on you set ignition to the same timing setting as noted. Disconnect vacuum advance. And your static advance should be about 15 BTDC or about 5 BTDC. 10 being a good figure. Put the vacuum back on. Open the throttle slowly until the vacuum drops maybe 6 or seven inches and your rpm’s come up to about 200, and see what the timing is. It should be for a typical street cam V8 engine should be about 25 to 30 degrees with the vacuum advance on. Mechanical advance may be about 15 degrees at that point. As you are going down the highway you want the non load speed at which you are driving you want to have the highest vacuum. See UnityMotorSports Video by Andy “the ultimate vacuum advance tuning guide”. There you GO.

On my old ford, I used to increase the vacuum advance to max, then road test and reduce the timing advance until it stopped pinging, then a little less. Like half a turn at a time. Always used manifold vacuum port and adjustable vacuum distributor. Was simple and easy to do with no equipment. It ran better and got better mileage. I am looking forward to using your method to compare the difference between the two methods.

Good info! Your doing a great job of filling the blanks left buy other channels. Appreciate it very much! Keep on!

Awesome video, sir! So this can be done when the weather changes as well I’m sure as part of a tuning seasonal… very cool! I am following you Rock the tune!

Hey Andy I’m just binge watching some older vidjas. Great vidja 🤙🏼

This is a super cool video....if you want to run on the street you got to know what your particular combo needs and vacuum advance is the way to go if you want any kind of MPG.... Plus you get drivablity as a bonus and clean plugs.

Manifold vacuum only! Get initial, mechanical advance and total timing properly set. Then start working on vacuum advance. Run all you can without detonation! Set the rate as aggressive as you can without detonation! Detonation testing is best done under engine load if you can find a good hill to climb.... You can tune out a lot of your cam lope with a lot of vacuum advance!!! Smoother idle for that sleeper sound! 😂

Would have loved to have seen your afr,s as you did this after watching your stuff on idle/ transition circuit mods, top stuff.

Thanks a lot Andy!! Great knowledge

I thank you and David for the invaluable information. If I remember correctly my friend Ken Shawver that ran stock elimtor and super stock ran a vacuum advance. I think he said it "cleaned up the idle "especially handy when going to the staging lanes. He also phased in the rotor. Another video? I watched other car going to the staging lanes a most of them would run rough and sometimes stall. And maybe even start some plug fouling? I found out the importance of vaccum advance from Davis books and helped me our alot on tuning small block chevys. I got alot of stories about but sometime later.

A few years ago now I asked a question on a forum about tuning by vacuum and if would increase mpg. The forum is very well known but is EFI related. I received 1 answer which was "it wont have any effect". I've been pottering away testing this on my own and have come to the conclusion your videos tell us. If we want performance and good mpg we must give the engine what is needs/wants otherwise we are short changing ourselves.

I have experimented with this but you just gave me a whole lot of methods to use to try to tune in my vac advance. My 74 Bronco with a slightly modified 302 burned out its last Ford electronic ign module, I'm done with Dura Spark! I swapped in a original 289HiPo dual point and it runs great under hard acceleration but lost "normal" driving manners, I want the low speed smoothness back and will be swapping a vac advance distributor back in.

We were doing this Saturday morning after watching your videos. But the car seemed to be quickly loosing power and we had a lifter tapping. Took it apart and found a lifter not pumped up and the cam is starting to round off. The Competition Cam lifters and camshaft only have around 1,000 miles on them. We have used Royal Purple oil with zink as a break in oil and then their normal zink oil ever since. We are going to throw a new lifter in it so we can take it to the second and last car show this weekend. So you are not alone in engines going bad.

Great video and explanation.

It is this simple , I worked for a speed shop when I was a teenager , my boss was a very knowledgeable guy. He always told me the vacuum advance always went to what he called progressive vacuum . So say your leaving a red light as you give your car gas it advances the timing. If you plug your vacuum line in and at idle and your timing advances its wrong.

Thank you for your insitghts and video 🙂❤👍 PS: Thats a strong motor

great fan shroud!

Andy this is what I need! I knew this is what the old guys did back before electronics and dynos... but I've never been able to tune properly with a vacuum gauge as you did. Some numb nuts lost my factory distributor and they installed a cheapo fancy HEI. They said it would be better and I argued the weights and vacuum advance diaphragm aren't tuned to my truck. It's never been right ever since. 1981 GMC c3500 350 Th400 14 bolt with 4.56:1 100% stock except a hydraulic liftgate. She's a heavy GVW so no feedback carb, ecm, cats, nor O2 sensors. All factory built. She's always loaded heavy and she's my backup tow vehicle. I can get 13-15 MPG on a 200 mile round trip loaded with maybe 1000 lbs of shtuff in the back but she's way down on power and hill climb performance. Could you explain a little further your chart/table you wrote ?

sound good my brother

This was really helpful

I like the Finnigan's Speed & Marine hat.

I didn't use the road test method a couple of years ago. I just limited the max the can added to 10*, reduced the initial to 4* for starters, on start timing jumps to 14* to 16*, and it idles smoothly even when cold. The engine vacuum jumped up to 20 to 21 inches in park, and at 65 cruise, engine vacuum is 16 to 17. This stuff really works well. I never considered using this with something like a tunnel ram. I guess this will work on a healthy single plane as well. Well Now.

👍🔔😎 Very good. There are/were vacuum cans that start to love at different vacuum levels There are cans that have different total amounts of degrees advance. The old Ford units of the 60s-70s had a hex outside the vacuum hose, and that hex unscrewed. Inside is a coil spring that resists vacuum. You can change the springs or put a washer shim under the spring to make it tighter. Some cans had the allen wrench adjustment to set the maximum degrees advance. Those Ford units converted to electronic distributors are excellent. JMO. Thanks HRR 😎😎😎

I would say the same goes for locking up the centrifugal advance. If you don't have the centrifugal advance working properly you are giving up lots of power and economy across the power band as well.

Im going to apply this to my 79 granada with a 250ci 6 along with changing the mechanical advance spring/s to see what it likes a 2bbl will come at a later date. Im running the original duraspark 2

Excellent, Thank You

Good stuff, thx!

I ran into this very issue with a 253@.050 cam in a street motor. The motor wanted tons of advance at idle, but was wayyy too much to actually drive with. Ended up using vacuum advance to give it a ton of advance at idle, that drops off right away when you punch the throttle. Perfect solution that was being used as long as engines have been made.

Great videos!! I wish you would show one with a Progression Ignition distributor. You can really dial it in those new units.

After watching this, part 1 makes way more sense.

Informative & thanks for sharing this. The only comment I would add - and maybe you covered this in another video is get your mechanical advance sorted out first, then work on your vacuum advance. I have been doing essentially what you cover in this video on every car I have owned going back..... 45 years! And it is well worth the effort. Thanks again.

Thank you 👍 👌

Hello, Great Video, that as a novice, I really want to understand. 1) Say you’re cruising at 3,500 RPM and the engine is making 15” of vacuum, so you keep adding hand pump vacuum until the engine does what, sounds stronger, picks up? 2) So once you know the vacuum it wants at a particular RPM, how to you set that / replicate it in your driveway ? I’m slow, thank you for your time, best, JR (any chance of a video where you take a car not running good and go through the whole procedure beginning to end?)

Can you do a 3rd video showing the final steps? Once I get needed vacuum on the gauges, how does that cross over to setting degrees of timing? Thanks

Just checking in and hope Casper's new engine is being built as you planned. I know it takes a lot to do video work when building something then edit all the video.

Caspar! What happened with the motor? You should be able to smoke a cigarette,drink a soda, eat a big-mac, text Uncle Tony, and call mom while doing this.ANDY ROCKS🤪🚙🔥🔥🔥💨💨💨

Andy, great video! Curious if you have used this same method of seeing what you engine wants while using the Progression Ignition distributor?

Yes, vacuum advance is vital for fuel economy and driveabilty. That is absolutely true. And yes, it´s also true that the engine might have other needs than you think it has. But it should be ported, not manifold vacuum. The reason for that is as follows: A ported vacuum advance will have the EXACT same ignition curve except when idling so you will get the same driveability and fuel economy, except if you spend a lot of time driving at idle only, which most of us doesn´t. And manifold vacuum will mean that a split second after the starter engages the engine will see almost full ignition advance which is very tough for the starter motor. Let´s say you have 10 degrees BTDC and 15 degrees of vacuum advance, that engine will have 10 degrees of advance when the starter motor begins turning the engine around but after half a turn on the crank shaft it will have let´s say 20 degrees of ignition and after another half turn it will have 25 degrees which can mean hitting the starter motor with some serious kickbacks. I heard that just a few days ago on a bigger engine. If you run ported vaccum the starter motor will never see antyhing more than 10 degrees which means very low risk of kickbacks. Even if you pump the throttle while starting it will have about 10 degrees of ignition since the throttle plates get the vacuum back to atmospheric pressure every time you pump that go-fast pedal. And 10 degrees is MUCH easier on the starter motor than 25 degrees. With the engine running, as fast as you open the throttle even a very small amount the ported vacuum will open to send vacuum to the distributor, saving fuel and increasing the driveability. The manifold vacuum should be used for vacuum modulators on transmissions, Corvette frogeyes, brake boosters (bigger concection) etc. I´m apologise for the language if needed, if you misunderstand that is because English isn´t my first language.

I'm struggling with this right now. Not perfect, but in the ballpark I think, Since my 400 hp Chevy small block in my 34 Roadster hot rod get a 25 mpg mileage on highway cruising. Probably much thank's to the 0.5 overdrive on 6th gear as well!

Awesome

Not sure what to do after you stated to note the timing compared to the vacuum you recorded? My 460 initial timing is at 15, Mechanical brings it to around 24, but when adding in the vacuum advance, it jumps to around 58, @ 3000RPM. This is timed port and no pinging and the engine really likes it. If I use the manifold vacuum, it does not seem to like it as much, mid RPM, starts to shake a bit. I tried to set the vacuum canister back all the way, counter clock wise and it made no difference. Any suggestions? Is this a bad vacuum pod? I was told, if the engine likes it where it is, leave it. Fuel economy seems good so far, will know more on that in the coming days. Thanks for the great videos!!

I set my vacuum advance i bit different. I set my throttle to form a sqare at the t slot. The i set the mix screws and flote hight. Then i adjust the timing with vacuum advance not conected for max stable vacuum then back the timing to drop the vacuum 1/2 hg. Then i take a timing reading and say it is 21* , and say the centrifical advance is 24* and i know that best take off happens at 6* of base timing .then the totel is 30* vary normal so then i know that 6* on the static timing is ok then i take 21* as that is best for idle so 21-6 =15* of vacuum advance. It works good for me! Keep us posted on the progress!

Hi, were you connect the vaccum hose, thanks!

Be interested to see if doing this with a tbi like a sniper would make a nice mpg increase

So you have the cannister hooked up to manifold vacuum? Thanks for posting.

What size Allen wrench

Will the vacuum be affected by the gear selection? Should my manual transmission be in 4th gear or 5th gear overdrive? Or does it make a difference? Your help would be appreciated

Since Casper is down you should have Dave Vizard do the video of the actual process once you have your numbers and you are back under the hood. That way we can see how to do it. Most mechanical guys are more visual learners. :) Do you need to get a different vacuum canister if you have an adjustable one? Great Video look forward to the final video.

Hi could you please make a follow up video on how you set the vacuum advance at each rpm settings you documented in just lost on how you make these setting at the different rpm ranges

How does this relate to Base/Initial timing?

thank you andy

Nobody EVERY explained this ! Or turned their car into a rolling road Dyno for SO LITTLE MONEY I thank you .

I wish I had seen this before I installed my new MSD no vac advance distributor .

If my 1949 Chevy sty line Deluxe with. New? Engine. New distributor rebuild carborator is hesitating on 1st 2nd and 3rd gear would it be? My vacuum advance any advice would help thanks

Can you give us the best order of tuning? Obviously initial Timing first but then Total Timing then adjust vacuum advance or…🤷‍♂️

Hey Andy: I'm a big fan of the channel, you, and David. Question: How do you replicate this process with the new Progression Ignition dizzy? I have had mine installed about a year and love it but interested in fine tuning the advance curve w/o a dyno?

My respect for David and you on this valuable information! but have you thought of trying a ‘Progression Ignition’ instead? Controlled electronically and tuned on your phone or tablet and it doesn’t rely on vacuum or weights.! just a thought....

say my advance is all in at 3000 rpm but my cruising rpm is between 2000 and 25000rpm what do i have to do to get the perfect vacuum advance for this cruising rpm?

First, thanks for the info on the vacuum advance setup! Subbed! Q1: In part 1 you mentioned a company that makes custom vacuum advance units. Who are they? Q2: _How do I sort out the mechanical advance?_ It's been mentioned in comments for both of these videos to get the mechanical advance sorted out first. Given the objectives of the Vacuum side you just covered, how do I figure out how to set up the mechanical advance? I know how to open it up and change it, but not _how_ it should be changed. BACKSTORY: I've been struggling to get decent mileage out of my 48 Willys CJ daily driver. It's got the wrong carb, but it's the only one I have. More on that in a minute. The engine is a 67 Dauntless V6. From the top down, it's got a 650 Edelbrock sitting on top of an Offenhauser Dual-Port* with a Comp Cams sub .5" lift torque cam. The motor is stock bore & stroke breathing out a hand-fabbed 'dual-Y' headers I 'mathed out' to be as correct as I know how for tubing dimensions and lengths. Between the stock 5.38 gears, 32" tires, and no overdrive, top speed is about 65mph at ~3650rpm. I rarely (like once a year) get into the secondaries so I don't worry much about the carb being 'too big' for a 225. Yeah, I could swap back to the stock 1bbl and intake, but the dinky primary runners on the Offy manifold give great torque and throttle response. Ignition is an unknown brand aftermarket HEI for an oddfire motor. I'm mixed on whether I like it or not. The computer (stock type) has shit itself twice now. The last time I was 90 miles from the nearest parts store out in the back-country of Idaho with no cell signal... Current mileage is between 7 and the rare 10 depending on how much gear I have loaded and whether or not the top is on. For a 2600 pound truck this is kinda bad. * Think of it as a single-plane manifold that has been split in two - the top third of the runners are a single plane fed from the primaries. The bottom two-thirds are a single plane fed by the secondaries.

At the risk of showing my ignorance, I have a question or two. I liked and understood the method you were using to obtain the information for the engine to tell you what it wants to choose it's vacuum canister settings, but I decided to go one step backwards and consider how the centrifigal advance gets optimized before that. After watching a number of videos and some reading, the general info seems to be 'mechanical advance all in by 3000 rpm' for a performance engine. That seems far too generalized in light of the train-of-thought to let the motor say what it wants. I was wondering if tuning the mechanical advance (before tuning vacuum advance) could use a similar approach... do not let the mechanical advance weights swing out as rpm's increase, but use a mity-vac on a vacuum canister to advance the timing for rpm's from say 1000 to 3000 rpm finding the optimized advance setting needed at different points in the 1000-3000 rpm range. Maybe all in is before 3000 rpm, or slightly higher. I welcome information if there is a blindspot in my mechanical advance understanding... THANKS FOR THE VID!

Great videos Andy! At 10:55 in this video, did you mean for the caption to say ‘16 mpg around town’? Or the other way around? Or maybe not, with 4.30 gears on the highway, 12.5 mpg would still be good! lol

I'm so damn confused, Is there a part three that will make sense of this video, what do you do with the numbers you get

So is there a part 3?You kind of left everyone hanging

So your dizzy hooked to port or manifold vac?

It's true I ran mainflod vac engine ran cooler and better performance than ported vacuum I do have have other concerns 351 Windsor .

It should be hooked to ported vacuum above the throttle plates.

@unityMotorsportsgarage I’m attempting to set up a basically stock 460 Ford Duraspark 2. If my idle advance is at 12°, virtually all of it is coming from the vacuum advance, meaning my base mechanical advance is virtually 0. I believe this is causing, a part throttle hesitation due to the lack of total advance. Conventional wisdom, would say move to port vacuum, raise the base timing for idle. However, I’m sold on your (David’s) theory on tuning. So do I’ve leave it at 0° and tear into the distributor to get more mechanical advance?

I have a DUI distributor that i had them build for me with all of the specs they require upon purchase (vehicle weight, rear gear, cam,cubic inch, converter stall etc etc) I'd have to go dig for the build sheet, but im pretty sure it was 23 degrees of mechanical advance and 12 degrees intial, putting me in the 34-36 sbc range..... now my question is, they never really talked about the advance canister and what kind of advance it pulls at a given amount of vacuum.... the advance canister is smooth and round so im guessing it isn't adjustable?? i wonder if a guy emailed/called DUI if they could shed any light on my question

Hey Andy. I'm currently running my PCV setup utilizing the manifold vacuum ports on both carbs. Do you believe I'd be okay running the PCV off of only one carburetor, so that I'd be able to use the other port/carb to run a vacuum advance? Thank you!

Wow!!! Andy that has blown my mind!! Never really thought much about the vacuum advance till now! And knowing your backed up by David Vizard shows your 100% real deal!! Thank you for this gem of a video! It seems much more relevant now than ever!! I’ve just purchased a 1972 Ford galaxy with what some call the boat anchor motor the 400M. I’m putting I. Forged flat top pistons which should bring the compression up to 9to1. And will be hanging intake cam carb, and ignition system. As it’s based on a 351 Cleveland with the 2V heads but with a longer block a few parts are able to fit my motor! With that can you offer me any information to help! I’d love to send my heads to David for porting and cam selection etc! That is a possibility once I’ve saved for a few months! If possible can I connect with you via email or on WhatsApp?

What's happening under the hood as you're cruising down the highway? Around 7:18, it looks like something is burning or glowing in the engine bay on the passenger side. You got gremlins under there smoking?

Soooo, we can just plug the “ported” vacuum port off the carb and just use the intake manifold vacuum ? Correct... ???? And with a adjustable vacuum advance tune it in.... 🤔👍

Hey mate , what if adding vacuum advance doesn’t increase my engine vacuum ? My can allows 20 degrees of vac advance but doesn’t seem to make a difference when I pump it in while cruising..

You never mentioned which port you use after you've adjusted the advance pod is it ported vacuum or manifold vacuum 🤔

Yeah.....I’m a little new to this,so what is your idle timing with the vacuum hooked up and at what rpm is your total mechanical timing all in? Just curious because I have a mechanical distributor with idle timing at 26 deg. advance and all mechanical timing in at 3200rpm at 36 deg. I too am running a tunnel ram on a 327 Chev. My vacuum reading at idle is 6.5 at 850 rpm.

I'm confused I have a vacuum advance and people tell me it connects to the carb.. your saying the manifold?

Where would you start with the initial mechanical timing before one begins to set the vacuum timing?

Ok, so I have watched number 1 and 2 of these videos half dozen times trying to follow this theory.. I don't know if I am the only one having a hard time figuring out this process or not but I am having extreme difficulty trying to understand how to execute this procedure. I understand that point of hooking the vac and gauge up and say getting to 2500 RPM and recording the reading of the gauge and the vac but I am completely lost at how to figure the numbers to get the timing.. I am a auto body and paint guy and can restore the body of your truck like it's no thing.. but when it comes to the engine tuning I am lost and it's difficult to understand some of this video.. basically once I get the recordings of the gauge I am completely lost to that point

My 49 Dodge Meadowbrook gets around 20 on the freeway with the 3.8 Flathead six.

So you're running manifold vacuum and not ported vacuum??? Do you have trouble with hot starts with your timing at 40 to 50 with it kicking back on the starter or with it pinging under a load accelerating?? I'm going to have to go back and watch video 1 & 2 again lol

Does it hold pressure. Or you have to keep pumping the hand pump.. thanks

You got Casper back together! Did I miss a video?

Are you guys still running any mechanical advance?? Or is it locked down and using all vacuum? Do you have a ballpark rule of thumb regarding that?

When you're on the highway, why's it look like there's flames under the hood?;

Interesting there's definitely some higher understanding I thought you should be all in around 2,000 to 2,500 32_34 degrees no more advance from 2,500 on I know what you mean in stop and go it gets hot like using the above throttle blade ported timed spark port on the carb I could surpass 14:7 on the AFR with less timing full manifold I'm lucky if I get 13:3 before it starts running like crap . Cooler yes but way richer

Wouldnt a chassis dyno be great for this? I had a engine once, i ran out of money, and had to run a modified computer controlled distributor, with no advance, it had near 13:1, and trying to run it on 93 octane, it got about 10 gallons to the mile, I had it rich, trying to fight detonation, i was young and dumb, it sounded great, 355cid, 285° 507" lunati cam, 750 holley, i put $150 in gas cruising town one weekend, and that's when 93, was under $1.79/gal. Over 20years ago, I did get some av gas once, that made night and day difference, i could give it more timing, i bet it gained atleast 50-60 HP, and a good bit if TQ! It smelled good too! Just like race gas, it was about $2.25/gal,, a decent distributor and more octane, it would been great!

Hey Andy,I've been out of commission. Still would love to see your technique applied to the distributor that I have. That is progressive ignition. You can tune with a cellphone.

Is this old footage or did you get casper going again?

That exit you got off on. Was it close to a restaurant Hillbilly's? I'm about 99% sure I know where your at.

Much easier with holley terminator and a laptop lol. I have a carb 383 camaro and holley efi turbo mustang. Both fun in different ways.