74 L-82-trying to get a little more power

[73shark]

First disconnect and plug the vacuum advance hose. Set your idle to factory specs. Hook up your timing lite and loosen the distributor hold down clamp. Now turn the dist. until the timing is correct. Don't be surprised if the idle speed changes. Reset the idle speed and recheck the timing. If the timing is changing at speeds below 1,000 rpm, then the mechanical advance is starting to come in. You can measure and plot your mechanical advance vs rpm if you have a dial back timing lite or a degreed harmonic balancer.

As someone suggested earlier, a kit that w/ get you all in by 2,500 to 2,800 rpm w/ work w/ the L-82. When done hook up your vacuum advance and reset idle if necessary. If you are using the ported vacuum, you probably won't see much change but if you are using manifold vacuum, then the rpm should jump up 100 rpm or more.

FWIW, I was using 12 degrees initial timing w/ mech all in @ 2,500 on 87 octane w/ the stock L-82. Now w/ 10:1 CR and a slightly more aggressive roller cam, I'm not sure where I'll wind up. May have to go w/ higher octane. Just have to wait and see.

 

[Rodney Gold]

Lemme tell you , the effort you are going to put into recurving your advance is most likely going to reap few rewards. You actually need 2 things to optimally adjust a timing curve , a way to select the total centifugal advance and and a way to adjust how fast it advances with respect to RPM.
You probably dont have a way of limiting or adjusting total centrifugal , you can use springs to adjust the advance curve tho ..but one without the other is not that useful.
If your dist has for example the usual 26-28 degrees cent advance built in , using weak springs to bring it all in at 2800 or below will often be counterproductive as you will have too much advance at low rpm , this will be noticeable when booting it in drive with less than an optimal kick down as you will get pinging and you will have to retard initial too much to get rid of it. If you had a way of limiting total centrifugal advance to lets say 22 degrees , you could run decent initial and not have a whole wodge of advance come in all of a sardine.

The easy way to set optimal timing for you is this.
Dont disconnect anything , just get the car to temp and find a hill , tootle up the hill at low RPM and boot the throttle , do not do this in drive as you dont want the car to to kick down , do it in 2nd gear if auto. Advance the timing till you just hear pinging when you do this test and then back off 2 degrees. End of story.
Vacuum will not play a part in this as there is zilch vacuum when you whack the loud pedal , vacuum advance doesnt matter unless you at light part throttle or at idle - even at full rpm , wide open throttle there is NO vacuum signal. So you dont have to disconnect vacuum advance when doing this test.
Whatever your timing is at idle after this test is irrelvant.
If you really want to check your initial timing at idle for future reference as to setting timing correctly , then after this test , disconnect vacuum advance and put a timing light on the car. Whatever it is , is the timing you can set it to at idle in future without repeating the test - assuming you havent changed anything like carb , headers etc.
PS before you do any of this , check your plugs and plug wires as to their condition
PPS turning a chevy distributor counter clockwise advances and clockwise retards.
PPPS an easy way of adjusting the dizzy is to loosen off the hold down so that it can JUSSST be turned by hand so its easy to adjust when doing the test. cinch it down after

 

[petes74ttop]

How to recurve your distributor

Go to Barry & Linda's Website at vettetech scroll down to "Ignition Systems" and click on "Distributor Installation" by Lars Grimsrud.

If you place an auto trans in 2nd it will still start in 1st but will not shift higher that 2nd. PG.

 

[73shark]

You can limit the total mech. advance by using the bushing that comes w/ most recurve and put it on the post that's under the advance plate and is in the slot.