Just ordered a new ignition system..

[69vettester]

In all honesty My Mallory dual point W/tachdrive (no vacuum advance) worked faultlessly but I have to watch the dwell setting constantly and it is more difficult adjusting dual contacts than a single!.
Plus..even Mallory calls these systems antiquated, and suggest upgrading them to newer technology.

So I just ordered a...
MSD-8572 MSD Pro-Billet Distributor w/tachdrive and adjustable vacuum advance (has an adjustable mechanical advance also)

and the mandatory module has to be at least a series 6....
so I got a...
MSD-6200 MSD Ignition Control Unit (msd 6a module)..
This is the lowest level module you can add into the system, it has no rev limiter.

The big question I have about this new distributor is :confused
The new distributor comes with a vacuum advance. I know what the optimal advance curve is for my motor but Im confused about what to do with this vacuum advance. It is adjustable, but should I disconnect it because its just an emmisions standards requirement (I have a 69 car) or am I wrong about that and I should tune it into my 300 hp , holley 600cfm 4160 vacuum secondary manual choke system) in order to get optimal performance (I do consider MPG as important). Hope I described this accurately.
Any advice, suggestions, previous experience comments are greatly appreciated.
Thanks in advance....pun intended :L
TomC

PS..I can somewhat justify the cost of this new ignition setup..cause Im going to put a 355hp motor in next year and this new ignition will be swapping to that motor. Ill put the mallory back in my present motor and try and get a decent price for it!

 

[69MyWay]

Excellent choice Tom.

A good hot ignition can make a huge difference in all around performance. Since you drive this car on the street, I would suggest you connect the vacuum advance. It gives you much better driveability. In terms of where to set the adjustable link, I would start in the middle.

Get an adjustable timing light. Attach the vacuum advance to the correct vacuum port on the carb start and warm the engine. Then, hold the RPM around 2500 with the vacuum advance attached and dial in the adjustable timing light to about 38 degrees of advance. Just set 38 into the timing light, then keep turning the distributor very slow and easy back and fourth until the timing light hits zero on the marker on the car. This usually takes two people to be safe.

Here is the benefit. That will put you where you want to be when thrashing it, yet, while driving normal the advance will move as needed with engine vacuum to make the engine run better in town. It really has nothing to do with emissions that I am aware of.

 

[69vettester]

Got it..

Thanks guys..the confusion in my tiny little brain is lifted. Thats exactly what I needed to know Chris..
The ignition, should be in the mail today so I should have it in by the first of next week. Ill be sure and keep you updated. Im pretty sure Ill have somemore questions as I install too
Thanks again
TomC

 

[redmist]

I'm using the 6A with a Petronixs HEI with adjustable vacuum.
I plug the vacuum and set the initial advance at 1000 RPM (radical cam) so the engine runs relatively smooth (20 degrees BTC). Then I change the springs so I get 36 degrees BTC by 3000 rpm. Finally I reattach the vacuum and adjust the can so I get 45 degrees BTC above 15 Hg of vacuum. This gives me good fuel mileage at cruise and the maximum "load" advance of 36 degrees below 5hg of vacuum.

 

[69vettester]

Redmist..
Ive heard your way , or real similar to your way discussed before.
It was in some articles by a real well known tuner, I think he writes articles for ZIP too. It was real complex to me and I was hoping that by using an adjustable light, I could bypass some of the steps? Any relevance with that?

Lars Grimsrud , You guys may have talked to him or read some of his tuning tips.

Ill try and find the article I had read to and post it here.
TomC

 

[rpounds]

Been running an MSD for a while now. In a word, I love it!! Plugs last longer and the maintenance is non-existant.

 

[69vettester]

Whahoo..thats for me

 

[Tom Bryant]

The vacuum advance is really for fuel economy and drivability as it advances the timing during high vacuum conditions. Obviously at WOT it does nothing. When you get your timing set up where you want it with one of the above methods you may find that you are getting a little pinging. Pinging usually occures at partial throttle when vacuum is still high. Don't retard the distributor, just adjust the vacuum advance to a stiffer setting until it goes away.

If you are getting knock at WOT you may have to adjust the centrifigal advance so your timing comes in a little slower. Of course this all depends on the quality of gas you have available, the condition of your engine, amount of carbon build up, ect. The nice part is you have a fully adjustable distriburor to play with. With a programmable timing light you can do everything that a pro could on a distributor machine, assuming you can find somebody that still has one.

Tom

 

[69vettester]

got that too 59tom..
Its For certain I dont have near compression ratio or the cam in this motor to be havin to retard the timing..so your info will prepare me about what to do and not be freaked ect should I get some detonation with the initial road test.

Im in California and it appears that 92 octane has given way almost totally to 91?? at least up north here where Im at. I watched this happen all summer to present and am pretty ticked off about it..Ca. is off the bat and down right full of crap about how to handle motor efficiency and emmisions standards in generalad I love to boost a tankful up to 100+ octane now and then , Man she really rumbles along schweetly when I do that

Found out today I wont be getting the setup till next thurs. or friday, so Ill have it in weekend after this. Cant wait!!Ill keep you all updated as I put it in. Gad maybe it'll just pop right in there and thats that till I change motors
TomC

 

[redmist]

Not to make your head explode but some nice complements to your set up, giving you some peice of mind and greater performance, would be to get a knock sensor and a air/fuel indicator. Instead of retarding your ignition you may be able to adjust the A/F (richen) if you have knock/pinging with a reasonable advance curve.
My next toy is a J&S Safeguard unit which automatically pulls in the timing if knocking begins. What you do is adavnce the hell out of the distributor and let the unit do it's job. Then reduce the advance untill the indicator lights just begin to flash. They also make a cool combination A/F meter and timing monitor. Very reasonably priced at about $500. (relatively speaking). Electromotive makes a pretty cool unit as well eliminating your distributor entirely, pulls in advance when needed etc etc. That unit is a little pricier.
But then again there is that mortgage payment to make.

 

[69vettester]

Redmist,
Heh..heh..exploding no, aching..probably. Its just a real outside chance Id have any detonation with this Motor anyway,
To tell you the truth If I did have like 11:1 cr+ I dont think I would have confidence with that kind of aproach anyway...I have alot of respect for motor detonation potential. I have a motor that I use a dynatec TC88 ignition with. I can program any curve I can dream up then link to the module with my pc and upload the new setting..pretty cool , Ive only had to use the built in curves though to make the motor detonation free in all ranges and conditions, a couple degrees of retard off stock, is where its set.
TomC

 

[Ken]

Redmist, I just gotta ask, is the "Redmist" handle in referrence to the quarterly motor racing magazine that focuses on the Ferrari team? Or is there some other connotation (other than the RedMist Castle free-form fantasy roleplaying game)?

The reason I ask is that I swear I heard a referrence to the "red mist" during a race at Laguna Seca or someplace, where someone got off into the dirt at one point, and I had never heard that term used before.

Just curious as usual.

_ken

 

[69MyWay]

Tom,

There is another benefit with that set up. When you switch motors and select a nice fuel injection system, you will easily be able to convert it over to a fully electronic pick up and toss the vacuum advance actuator out the window.

I bet you will see a mile or two improvement in your MPG just as soon as you get that on your current motor and tweak it into place.

 

[69vettester]

Chris,
Heh..Heh..
I did a purty good research on my potential to ever have a EFI in this car.
I bailed on the idea..
The reason is the complexity and cost to do that degree of power upgrade, put it out of my range.
I could probably save and make the price part happen, But it just doesnt pan out with the complexity part. (which system and why ect)
How should I put it..The things I have to consider and would have to do get more exponential trying to button an EFI into my engine compartment and The benefeit of doing it just doesnt trade off enough! For me to do it that is.
But...
I think I know where your comming from though...
Your interested to see some one do it and see how they go about it. :gap I am too..ha..but it wont be me this time.
TomC

 

[69vettester]

tuning..

Heres How The vette tuner..Lars Grimsrud describes it..

QUOTE
36 degrees total mechanical advance, when the centrifugal is all the way in and with the vacuum disconnected, is a very good general spec for any GM V8, providing you're not running the fast-burn style heads. Fast-burns will take less total timing (about 34 max). If you're at higher elevations, you can run a little more (up to 38 or 40). If you have access to a track, you can start with 36 total, then advance and retard 2 degrees at a time to maximize trap speed. You'll find that max trap speed will put your total timing somewhere between 34 and 38 degrees in virtually all cases.
For peak performance, you want this total timing to be all in at or around your torque peak - about 2500 rpm in most cases. Lighter cars can take a quicker advance, whereas heavier cars and trucks may need a slower curve to prevent detonation. The Vettes perform very well with the centrifugal fully in anywhere between 2000 - 2800 rpm.

With a quick, aggressive curve like this, it is important to match a complimenting vacuum advance curve to the mechanical curve. A GM V8 will take up to 52 degrees of total mechanical and vacuum advance at light throttle cruise speed. If you're turning 2500 - 2800 rpm at cruise, that means that you have 36 degrees of mechanical advance slammed in at cruise speed. You cannot run a vacuum advance producing more than 16 degrees of advance to avoid exceeding the 52-degree limit. If you run more than 52 degrees total advance at cruise, the car will start to "buck" and "jerk" while running down the highway - very common problem when using a stock vacuum advance control unit with a re-curved mechanical advance curve (most stock vac advance units produce 18 - 24 degrees of vac advance). Many people will disconnect the vac advance to "improve" performance and eliminate the "jerking." This, however, has an adverse effect on mileage and cruise rpm throttle response. You're much better off installing a vac advance that produces 16 degrees of advance than to eliminate the vac advance.
UNQUOTE


TomC

 

[Tom Bryant]

Tom

This looks a good post to submit to the Tech Center.

Tom

 

[redmist]

I'm petrified of detonation as well.
FYI "redmist" is a racing term used to indicate a driver who has stopped watching the tach, oil pressure, tires etc , whose field of vision has narrowed, has ignored all the laws of physics and whose sole focus is overtaking all those in front of him at any cost.
When I attended the Formula Ford Skip Barber course the instructor characterised my condition as such on during the first hot lap day. This is not a complement and he was correct. I relaxed a little the second day.
The most important thing I learned was to grip the wheel lightly, save your tires and be totally unemotional.
I forget this often.

 

[69vettester]

59tom
I submitted the article via the tech center form but it might have failed to go anywhere..(domain not on server)???..
TomC

 

[Ken]

...and be totally unemotional.
I forget this often.

:L

Thanks for explaining it.

_ken

 

[Bullitt]

Unemotional???????

Hell, where's the fun in that?! Most race drivers I've watched, including the guys in F1, end up shaking a fist at their opponents. You can almost hear them saying, "Out of the way IDIOT!!!" ad The emotion and tension between the most classic rivalries, like Senna vs. Prost, are what make racing the most passionate form of competition. Forget all about stick and ball games. Roaring engines, fire shooting out of the exhaust, trasmissions whining, 200mph speeds, hundreds of horsepower, squealing tires, countless hours of dedication, sweat, blood and anxiety, sleep depravation, the wave of emotion that consumes you-- all that just to take the chechered flag first. And the ability to say, "On this day, I was the absolute best!" How can you not be emotional? --Bullitt