This is just an FYI of my experience and my results may be of interest to those interested in more power, improved drivability and dramatically better performance and milage.

I've been experimenting with my Super Six'd 225 with bigger valves, head cut .080, HEI conversion, 350 cfm Holley 2bbl, Doc's smaller Erson cam and his famous duals.

I've found my motor loves the initial timing set at 25 BTDC with the total set at 35 BTDC. The timing is all in around 2000 rpm. Of course, I had to weld up the slots in the mechanical advance to pull this off. I'm also running vacuum advance hooked to manifold vacuum, so the timing at idle etc is even more advanced.

The motor runs fantastic, starts right up hot or cold and doesn't ping or gas knock. I have WAY more torque and horsepower and improved milage. I have yet to find a downside.

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1968 Plymouth Barracuda Convertible Super six

This doesn't make a lot of sense unless your timing marks aren't accurate.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Or didn't degree the cam...

-D.Idiot

I understand your scepticisim, but it is what it is. While it's possible that any of our dampner outer rings have slipped, the guy who assembled the long block claims he's done more than a few slant builds. As part of this build, he degreed the cam and verified the timing marks.

Have you ever tried this timing set-up?

I followed the pattern I've found works very well on a big block mopar I have. That motor has more cam though, and likes 21 initial with 34 total, all in before 2000 rpm, no vacuum advance.

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1968 Plymouth Barracuda Convertible Super six

Maybe and maybe not. Fact is, what you're claiming to work so well goes against the most basic engine operational principles, so the more likely possibility is "it isn't what you think it is".
…okeh...yeah, probably, given who it looks like it was…
I don't run square wheels and tires, either.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

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1968 Plymouth Barracuda Convertible Super six

LOL.. Ummm hafta excuse Dan, sometimes hes just an ole skeptic... (kidding Dan, just poking fun) A couple of questions arise from your findings... 1 is dont know your location, so therefor dont know your elevation of your habitat, 2 is dont know know the driving conditions you are running in.. ie: flat lands, hills,etc... You may just have found a happy combo for all of the above conditions for your set up. You never stated your beginning mileage v what you get now etc.... Sometimes what works works, but wont work for everyone, nor can it be duplicated, no matter how exact someone else tries...

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MRO....

Cheap, Fast, Reliable.... Pick 2...

The ones that tell us which direction the pistons are moving during the four phases of the 4-stroke Otto cycle.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

It's all good. I don't object to being called a skeptic—I am, and I don't apologise for it, either. It means when someone puts a dubious claim in front of my face, my eyebrow is going to be raised to the fully upright and locked position until the claim is supported with sound science (handwaving and guesses and shrugs don't cut it) or at least some repeatability as a first step.

The guy says his engine runs great? His engine probably runs great. No reason to disbelieve that. But there's something screwy in the described ignition timing setup. When someone thinks he sees something that doesn't accord with the operating principle of a machine—or with physics, or with optics, or with physiology, or with whatever other branch of science (i.e., knowledge) is involved in whatever's being looked at—it's usually because he's either not understanding it correctly, or not seeing what he thinks he's seeing.
…and the primary main number-one reality test, the basic foundation of the scientific method, is "Can the finding be repeated?".

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

There are many downsides to your system. Two big ones:

(1) By running the vacuum advance off the intake vacuum instead of the correct ported vacuum source on the carb, you are running full vacuum advance nearly all the time. The only time you won't have full vacuum advance is if the manifold vacuum drops to a level below the vacuum required to activate the vacuum advance.

(2) You say your base timing is 25 BTDC at idle, your max timing is 35 BTDC all in by 2000 RPM. This means you have a total of ten degrees advance and it is all in before 2000 RPM. This is a very small amount of timing advance and it comes in very quickly. You are loosing MPG and performance.

Try this: first, verify that the timing mark on the vibration damper is, in fact, still accurate and the motor is truly at TDC on cylinder 1 when the timing mark is at 0. Second, keep track of your fuel economy over several tanks of gas and, if you have a smart phone, get a program like Dynolicious that gives you some rough accelerometer and G force readings along with horsepower estimates. Third, go back and hook your vacuum advance to the ported vacuum source on your carb and set your base timing to something more reasonable like 10 or 12 BTDC. Fourth, keep track of your fuel economy over several tankfuls and get new readings of the power of the motor using the smart phone app. I'll bet both MPG and power increase when you get the timing set up correctly. You will likely need to return the carb and file out or replace the welded up slots in the distributor.

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Casually looking for a Clifford hyperpak intake for cheap.

All right sports fans, do we have any volunteers to check repeatability?

You'd have to modify and recurve your distributors to shorten up the mechanical advance in them to only give about 10 to 15 degrees mechanical advance at the crank? (welding up the slots a bit and filing them with a chainsaw sharpening file is prefered, but some people have epoxied them)

A dial back timing light works well, but timing tape and a static timing light will work too.

Your total timing will remain between 32 and 35 total. (This doesn't change/ no vacuum advance hooked up during testing)

Your initial timing will end up in the high teens to low/mid to 20's.

You will use light enough advance springs to bring all your mechanical timing it just below an RPM that you typically cruise on the highway with.

Then your vacuum advance will be hooked to manifold vacuum and the travel adjusted to suit your particular applications needs on the freeway at cruise.

It will be nice if several people try this and report their results. The good news is, you can always file the advance slots back to where they were if you want to go back to the stock amount of mechanical advance.

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1968 Plymouth Barracuda Convertible Super six

That is a great advance setup for a huge hp sbc in a race only situation.

For a street slant....no

To duplicate your results we need to know what else you screwed up to require this curve.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

It works, it's simple and it's repeatable. When I set the timing up with a factory distributor, the car runs fine, just as I would expect a slant to run. With this timing set-up, the car is significantly stronger off idle through redline. It has lots more off idle and midrange torque.

All those who got scared can relax now, and after they settle down, keep their car the way they like it. I realize people mock what they do not understand. It's to be expected.

For those who like to experiment in the quest for more power and performance; it's easy, reversable and worth a try. What do you have to loose?

I'm not changing mine back. It just runs too darn good like this.

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1968 Plymouth Barracuda Convertible Super six

Have you verified that the timing mark on the outer ring of your vibration dampener is correct?

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Casually looking for a Clifford hyperpak intake for cheap.

So you keep saying. But no matter how often you say it, it's still flying in the face of various very stubborn aspects of reality, so just continuing to say "it works. It works. It works" is not convincing.
The (real) explanation for what you (think you're) seeing probably is simple, yes. We don't have it yet.
We don't know that yet. So far, nobody else agrees with you.
There's a lack of understanding here, alright, but, um, how to say this politely…it's not on our end.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.