Initial timing is set at 6 degrees. Total timing without vacuum is 31 degrees. With vacuum can hooked up total timing goes up to 57 degrees.

Is anything wrong with any of these numbers? Can I increase my initial timing another 5 degrees to bring my total w/o vacuum to 36 degrees?

Is my timing with vacuum hooked up way to high?

Mark, without knowing your engine specs, most mild performance small blocks like 14-18 degrees initial. It seems like you have way too much mechanical advance. What kind of distributor are you using?

Mike

Initial timing is set at 6 degrees. Total timing without vacuum is 31 degrees. With vacuum can hooked up total timing goes up to 57 degrees.

Is anything wrong with any of these numbers? Can I increase my initial timing another 5 degrees to bring my total w/o vacuum to 36 degrees?

Is my timing with vacuum hooked up way to high?


:confused: Start setting your initial at around 15-16 and change the springs in the distributor to your total is around 36. Look at MSD's chart to figure out what spring to use. Around 21. Use around a 2700 rpm curve. I never heard of 26* advance from the can. My MSD is around 16. So 36+16= 52.

This is just a starting point.

Initial timing is set at 6 degrees. Total timing without vacuum is 31 degrees. With vacuum can hooked up total timing goes up to 57 degrees.

Is anything wrong with any of these numbers? Can I increase my initial timing another 5 degrees to bring my total w/o vacuum to 36 degrees?

Is my timing with vacuum hooked up way to high?

Sounds fine to me - you have the typical 24*-25* centrifugal in the distributor. I usually suggest 10*-12* initial with 36* total as a starting point, and that's what you'll have if you increase initial another 5*.

Your vacuum advance should add about 15*; you can verify that at idle by connecting it and disconnecting it and noting the difference between the two timing readings (assuming it's connected to full manifold vacuum and the vacuum advance unit is properly matched to your idle vacuum level). At idle, you should see your initial plus the vacuum advance (around 25* if your initial is set at 10*).

:beers:

:beers:

Start setting your initial at around 15-16 and change the springs in the distributor to your total is around 36.

Changing springs DOES NOT change the total advance, it changes the rate of adevance
With vacuum can hooked up total timing goes up to 57 degrees.
%& is way to high..think of it like this...you are cruising down the highway with enough engine vac (assuming that the VA vac range specs are low enough) and rpms to have every thing in ...thIt is firing and peak explosion when the piston is still coming up, loading rods bearings crank and most probrly detonation destoring the internals of the engine.

Like John says set up cent in the 36 deg all in ball park, but you VA has to be tunes to your idle Vac and vechilce vac behavour under cruise, light loads and rpms.
This varies from car to car ...weight, overall final drive ratios, engine design are all factors.

Always thought the total did not include any vacuum advance. Total 36* mechanical only.

Always thought the total did not include any vacuum advance. Total 36* mechanical only.That's what I thought - at WOT vacuum advance is zero (assuming manifold vac is use) and much less than total under a load too at high RPM. I ran over 50 degrees overall in my street strip car for years with a vacuum advance distributor and never had a problem.

I agree, I run 50-55 degrees at cruise with the vac advance on all my cars, it's not only fine it's proper.

I'd get my initial up a little until you're all in at around 36 at 2500 rpm or so. then hook your vac up and see where you are, if you're anything past 55 and you probably will be you can limit your vacuum advance with either an adjustable kit or welding the slot in a little. I'd just get the kit myself it's the right way to do it.

I run around 57*-62* 18*-20* initial with no problems.
I do need to adjust the vacuum can though to take some out.
Your timing isn't hurting anything, but your initial is low even for a stock-ish build.

%& is way to high..think of it like this...you are cruising down the highway with enough engine vac (assuming that the VA vac range specs are low enough) and rpms to have every thing in ...thIt is firing and peak explosion when the piston is still coming up, loading rods bearings crank and most probrly detonation destoring the internals of the engine.

Like John says set up cent in the 36 deg all in ball park, but you VA has to be tunes to your idle Vac and vechilce vac behavour under cruise, light loads and rpms.
This varies from car to car ...weight, overall final drive ratios, engine design are all factors.


The idle vac is not too high. I have my car set up pulling full vac at idle. So that's around 32* at idle (full vac port). 19* vac + 13* initial = 32* .I changed my canister to pull full vac at 8" because my car idles at 12". Car likes that alot better that just 12*. I have the springs set to be all in at 2500 rpm.

13* initial
19* vac ( plugged into Full vac port ) Total 32* at idle
21* mechanical ( using the black bushing )
All in at 2800 ( 2 silver springs )
Total of 53*

My car runs ALOT cooler and idles 10x better. The advanced timing allows you to close the throttle blades a bit more.

And how many miles has your engine done?
100,000 yet?

And how many miles has your engine done?
100,000 yet?

A few thousand. Why does this seem crazy to you?

I sort of go backwards. I start by setting my mechanical at 36 degrees, all in by 3000 RPM. I let my initial fall where it falls, usually 15-16 degrees.

Here's a trick to find 36 degrees if your harmonic isn't marked for readings that high:

Measure the circumference of the harmonic with a paper measuring tape similar to what's used for sewing. For instance, if you have an 8" harmonic, the circumference should be very close to 25-1/8" (8 x 3.1416 or pi). Since a circle is 360 degrees, 36 degrees is a 1/10 of 25-1/8" or just a fraction over 2.5" from the dead center line on the harmonic. Mark that spot, disconnect and plug the the VA hose, then set her at 36 degrees at 3000 RPM.

Also, most of us are running manifold vacuum which activates the VA at idle, further increasing the advance at idle, which is good for a cooler running engine, mileage (if we care), and off-idle performance.

FWIW

I sort of go backwards. I start by setting my mechanical at 36 degrees, all in by 3000 RPM. I let my initial fall where it falls, usually 15-16 degrees.

Here's a trick to find 36 degrees if your harmonic isn't marked for readings that high:

Measure the circumference of the harmonic with a paper measuring tape similar to what's used for sewing. For instance, if you have an 8" harmonic, the circumference should be very close to 25-1/8" (8 x 3.1416 or pi). Since a circle is 360 degrees, 36 degrees is a 1/10 of 25-1/8" or just a fraction over 2.5" from the dead center line on the harmonic. Mark that spot, disconnect and plug the the VA hose, then set her at 36 degrees at 3000 RPM.

Also, most of us are running manifold vacuum which activates the VA at idle, further increasing the advance at idle, which is good for a cooler running engine, mileage (if we care), and off-idle performance.

FWIW

:thumbsup: Exactly.. The only problem I had was I idle at 12-13" so the timing was jumping around. The can starts to open around there. Thats why I changed the can to open full at 8". Works perfect.

I sort of go backwards. I start by setting my mechanical at 36 degrees, all in by 3000 RPM. I let my initial fall where it falls, usually 15-16 degrees.

Here's a trick to find 36 degrees if your harmonic isn't marked for readings that high:

Measure the circumference of the harmonic with a paper measuring tape similar to what's used for sewing. For instance, if you have an 8" harmonic, the circumference should be very close to 25-1/8" (8 x 3.1416 or pi). Since a circle is 360 degrees, 36 degrees is a 1/10 of 25-1/8" or just a fraction over 2.5" from the dead center line on the harmonic. Mark that spot, disconnect and plug the the VA hose, then set her at 36 degrees at 3000 RPM.

Also, most of us are running manifold vacuum which activates the VA at idle, further increasing the advance at idle, which is good for a cooler running engine, mileage (if we care), and off-idle performance.

FWIW

:thumbsup: Exactly.. The olny problem I had was I idle at 12-13" so the timing was jumping around. The can starts to open around there. Thats why I changed the can to open full at 8". Works perfect.

I just ordered the MSD 6530 so all that goes out the window with setting up:sad: Now it's all done by a laptop and MAP sensor.:clonk:

And how many miles has your engine done?
100,000 yet?

A few thousand. Why does this seem crazy to you?

because you will not see the effect of over advancing till the engine has seen good milage, over advancing is the difference between a 30K engine and a 100k/200K + engine.

If you look in the AC Delco service manual you will find 100s of diferent dizy specs and 100s of different VA canisters...each slightly different for variations in vechile types, engines cams, heads, weight, models, yrs etc etc.
Why a 302 dizzy has different specs to a 295 hp 350 which is diferent to a 255 hp.
Curves are a science, not a hit and miss aplication
You really think manufactures spend a fortune on dizzy curves, manufacture 1000s of models justfor the fun or performance?

I'll get back to you in 100k and let you know.