What is the total amount of advance with vacuum advance hooked up on a 340/416 stroker engine? My engine builder says that the weights in his opinion travel to far.He said it is going to 39-40 deg. advance with the vacuum hooked up.

I wouldn't be surprised to see 50-55 degrees advance with a vacuum advance (10-15 over total centrifugal). Depends on the individual components.

I would disconnect the vacume advance to determine the total mechanical advance and go from there. I recently installed a new vacume canister on a RB pump gas street motor for a customer, it would hold 51 degrees total revved up above 2000 RPM, with it disconnected it had 34 degrees total mechanical and 19 degrees at idle Which is what it(34 total) will have at WOT

If it is a stock musclecar era distributor that is unmodified then it will have about 30 degrees , or more, of mechanical advance. For a HI performance application it's going to have to be modified if you need more initial advance.

They are getting less and less common, but I wonder if you could find a shop with a Distributor Testing Machine?

http://www.youtube.com/watch?v=aSBb92kP2KI

Well, I incorrectly posted...
The distributor with the vacuum advance "Disconnected" and the initial advance set at 14 deg.... the weights travel too far and give me a total of 39/40 deg

get one of the FBO limiter plates/spring kits to drop in there.

has slots for 10* 12* 14* 16* 18* & 0* lock out.

I have the 440 at 18* initial & limiter plate on 18* for 36 total

got the 318 at 14* initial & limiter plate on 18* for 32*

vac advance capped

my junk runs way better now.

Again ...

I would suggest setting the initial with the "vac gauge method" then install the FBO plate to get 35 total (initial from that + slots) and toss the heavy spring with the elongated loop & sub in a mr gasket or MP light spring in its place for a start & mix & match the springs (source some other ones as needed) so that you are just under the pinging point at WOT up thru the gears on your hottest/driest day then hookup the can to ported (if your hot idle RPM is reasonably low enough to use ported) & with a 3/32" allen wrench bring it in as fast as you can but staying just under the pinging point in everyday driving at varying RPM/load (in hg) conditions & CW brings it in faster. On the (2) pinging tests give your self some cushion as it is hard to hear ALL pinging plus there is silent ping & gas ain't getting any better. any ping you can hear is WAY too much. Add speedway motors shims under the plastic collar to reduce the axial play to .005" and add the 1/2" ID metal collar on the lower shaft and or peen the tang on the shaft end to reduce the tang/intergear notch interface rotational play to near zero. add (solder on) to the side of the dist a side oiler cup like the 60's dists had (they're out there Grainger maybe). check/correct rotor phasing. lengthen the rotor blade tip till the clearance to cap terminals is .015". keep the cap/rotor brass tip edges filed sharp (reduces required voltage to jump aross). use a good tan cap with ribs and drill a 1/2" vent hole in the top to let ionized air molecules out & this also lets you check rotor phasing in action plus several holes on the sides. EDIT brass terminals in the cap

The "right" total timing is specific for the engine/application. But generally speaking, the small block guy seem to settle on numbers around 34°. I cannot tell you what is right for your situation.

You will need to adjust the weight travel if you want 14° initial, and 34° total

Look at the number stamped on the VA can arm & double it & that is the amt of addit'l adv the eng will see on the crank with your light. Might be (8) (11) (13) or more (that # then times two). with the can hooked up you will for sure have more than 39-40. Sure he didn't mean 39-40 WO the can? EDIT some strokers do have different total requirements for spot on but 35 (can capped) is a VG SB baseline to start with

Im in the middle of a 451 buld and have been researching advance curves and what not and found this gem of an idea

http://www.autospeed.com/cms/article.html?&A=0353

Basically a walkman (remember those?) style hearing aid converted to an stethoscope - useful while tuning only, but according to the article you can hear the knock well before a sensor would detect it

Besides the VA can arm being marked, so are the mech adv weights.
Find some junk dists you can rob parts out of and find ones that will get you to where you need to be. I've seen them as low as 9.5* or X2=19*, as with the vac can, multiply number on the weight by 2 for the amount of adv it will give....or just order the adv plate from FBO.

Remember vac advance only works at low rpm with high vacuum, full throttle zero vacuum. Used as a transition till mechanical advance takes over. If you're set initial at 14 you probably won't need much vacuum advance, they can be adjusted however, Allen wrench inside the tube where hose goes. If idled high you're out of the transition slot anyway and could reduce signal too. Advance with a load makes it ping, same advance just cruising no ping, within reason( no 50 degrees). Have hooked up to straight vacuum to get a high cruise degree, throttle almost closed. then when throttle opens vacuum drops, degrees go down no ping. Never finished the project, dude sold the car so I couldn't get It dial in properly, did help mpg.