Hey guys, my advance can arm has 6.5X stamped on it, it that an ok dizzy?? Anyone else have one of these; should I do anything different to it?
Thanks,
BBBanjo

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225 Cubic Inches of Iron-Head American Muscle

225 bored .040 /.100 off block, Schneider Cam 224@.050~ .480 lift - Stock valves, blended bowls, Offenhauser intake with 500 Edelbrock carb

6.5 x 2 = 13 degree of vacuum advance, that is OK but the real question: is your vacuum advance "pod" an adjustable rate version?

Vacuum advance is only one part of the distributor advance curve. You need to also look at the mechanical advance govenor plate (slotted plate) and the spring rates on the weights to figure-out the complete curve.
DD

Hey Doc,
How do I get said-slotted plate out of the dizzy? I tried earlier, and no luck. I just don't understand how it comes out....
The can is adjustable.....
I've been reading up on setting timing curves, and from what I've read, I need to either put the two lightest springs from a GM kit on it, or the light stock one, and 1 GM spring. Please inform me if I understand wrong.
Thanks,
BBBanjo

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225 Cubic Inches of Iron-Head American Muscle

225 bored .040 /.100 off block, Schneider Cam 224@.050~ .480 lift - Stock valves, blended bowls, Offenhauser intake with 500 Edelbrock carb

where is your cruise rpm and vaccuum level???

How do I get said-slotted plate out of the dizzy?

Pull the reluctor, vacc. advance and pick up plate using screwdrivers to pull the screws out of the body, then prying the reluctor out with two screwdirvers and some easy firm pressure. Put dizzy under a bright light, look into the shaft the rotor goes on, inside will be a felt pad (sometimes), and under that will be a bent hairpin, use skinny needle nose pliers to pull felt out, then pull the hair pin out, governor will come out after that...if you pull the plate, or can rotate the governor into view after pulling the vacc. advance and it already says R9 or L9 or 10 or even 11, leave it, reassemble and gap pickup per the book.

I've been reading up on setting timing curves, and from what I've read, I need to either put the two lightest springs from a GM kit on it, or the light stock one, and 1 GM spring. Please inform me if I understand wrong.

It will all depend on whether your car is all drag, going to the street, what carb you're running, what vacc. you make at cruise conditions, what rpm you have at cruise conditions and take off (running a lot of curve right off the bat with a stock engine makes for a lot of bad mileage, pinging, and sluggishness). Have a spare working distributor handy to get the car running and around town, use the one you modify to check with a vacc. gauge in car, tach in car, then a tach and dial back timing light in the driveway...you'll have to plot the curve(rpm vs. degrees on governor or mech advance alone, then another one with vacc. applied vs. degrees advanced)....only one change at a time when dialing it all in...no one curve is correct for all cars...but the formula for a "happy" performance curve is vacc. + mech. @ 50 degrees, mech @ 30 total...


good luck, welcome to the hair pulling contest...

-D.Idiot

See

http://www.slantsix.org/forum/viewtopic.php?t=13264


for my trials and tribulations.....

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I have found success in running a Light Spring from the Gm or Chrysler kit in place of the heavy one from the factory.


Then I disconnect the Vac unit. Has worked well for me.

I set intital to 12*


all in 2200~2500 Total 32*

I never messed with the plates -- I am not saying it's right, it just worked for me.


Greg

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http://www.youtube.com/hyperpack

Ed,

Thanks for the continuing recurving input! I have been restudying your "textbook" since I am now back to recurving, and wonder:

In your June 25, 2005 post you noted you had the Mcmaster springs at 17 lbs/in. When you cut off loops, I can see several ways to "calculate" the spring rate, but wonder if you can share how you did it. For example, it is easy to understand brazing and filling the reluctor hole until a decimal size slot is left, but do you calculate the spring by miking the coil lenth before cutting, then divide the number of coils into that length to get a deciimal, then divide that decimal into 17 to see how many lbs one coil is? Or...?

Thanks!
rock
'64d100

You also need to determine the weight of the vehical (a curve for a light car will not be happy in a heavy vehical, and vice versa), type of driving (around town, mostly freeway, street/strip, etc). On my 3600+ lb Satellite, I curved my distributer so I can get some snap off the line for city driving (by using the lightest spring I could find among the slant and big block distributers I had) and using a short heavy spring, so the advance is slowed some untill I reach usual highway speeds (60-70) with an 11R governer. I also adjusted the vacuum advance pod (cant remember what was stamped on the arm) so it comes on at a higher rpm (again, around freeway speed, about 2200-2500rpm). It runs at 32 degrees total advance. This works for me, but may not work as well for a lighter car, or a heavier truck. Yes, it took about a month of dinking around to get it to where I like it. Tear into it!!

You can either go by length or or coils............

1/2 the amount of coils (or length) is twice the spring rate. (coils is easier).

i.e. you start with 10 coils and cut down to 8.5 coils: spring rate is (10/8.5) higher......... (~1.18) so if this was the 17lb/in, now you have 20lbs/in.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes