Based on stock engines, and it's been a while, I'm going to go with Steve on this. I ran a timing computer and a Delco vacuum unit for quite a while. It let me keep the tach drive dizzy in my 55 bird, without spending $700 on a 57 tach drive in need of a rebuild.

The motor will probably take the full vacumn advance at cruise, but you may find a part throttle (60-90% throttle) ping. That's going to be the time to limit the vacuum advance adjustment if it has one.

I had a vacumn gauge in the car, and a hand held vacumn pump, so I could get a second set of hands and look at the advance curve at different vacumn and rpm levels. Bunch of work, and not really needed.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

I hope you still have the MSD8383 instruction manual. According to the installation instructions, the MSD 8383 distributor comes with the "BLUE" advance stop bushing installed - that is 21º at the crankshaft. The stock engine will operate well with a total of 35º of mechanical advance. So - as delivered it would tolerate an initial crank setting of 14º. It also comes with a factory set of advance springs - (2) HEAVY SILVER springs - and per the included chart, they would reach full travel at about 4000 rpm together with the BLUE bushing. The default RPM limit is 10,000 RPM - don't go there OK?. 

Myself, I would suggest the following set-up for a stock engine:
Initial advance at idle 10º
Use the SILVER advance stop bushing (replace the BLUE bushing) to get a 25º limit ,the sum of these being the 35º total
Change out the HEAVY SILVER springs with two of the LIGHT BLUE (for poor gas) as the advance would be all in at 3500 rpm. Using one of the LIGHT SILVER and one of the LIGHT BLUE (better gas) springs would net full advance at about 2800 rpm.  

There are no instructions included for the vacuum pot - only a ramp. Many of the vacuum pots have an internal screw that will adjust the "FULL" advance of the unit - but this one is an unknown. Given that these engines in good tune with a factory cam will easily deliver 15 inches of vacuum - it could be adding as much as 16º of additional advance at high vacuum - and that might be a bit too much. 

 
 Steve Metzger       Tucson, Arizona

MSD 8383

Yes, that's one of the items I need, thank you.

My timing marks were covered in 30 years of rattle can paint.
One hack I came up with was to get a sheet of the timing tapes I can't remember the diameter right now, but easy to figure out by math or a measuring tape--and mounted it semi permanently with some 3M 2 sided body tape once I found TDC. The tape as a temp fix is still going strong after 4 years. Wasn't planning on the fix lasting this long, but not complaining.

Mike Rizzo

1963 F100 "Rudy"

Daniel Island, SC

So - you still don't have a target number for the initial advance setting. A stock engine will like about 10º BTDC. Sometimes - you have to strip the paint off the dampener - and carefully scrub the wheel to get a mark to show. These engines will idle really slow - adding timing will add speed and torque and make it hold idle in gear.
The comments above about the Holley carb - need some illustration. The primary blade has to be properly positioned on the "transfer slot" down inside the carb throat. Without this precaution, the engine will stumble badly and have a very poor transfer from idle to "run". You can best see that blade position - when the carb is off the engine and inverted.


It takes tremendous will power but - once it is set-up - it shouldn't be moved while trying to adjust the idle.......only the mixture screws. The amount of additional throttle to keep the engine running should come - as mentioned above - from the secondary side of the carb. Each of the secondary bores has a "dribble port" for lack of a better name, where fuel constantly bleeds out of the secondary bowl through a small orifice. There is a small screw on the bottom of the carb - just below the secondary pot - that will hold the secondary blades open a bit - add air - and provide idle air to the engine. It can only be seen when the carb is off the engine - and most 4 barrel manifolds have a clearance below it.

Personally, I often replace the screw with a slightly longer bit of thread (cut off a longer screw) so something will protrude below - that I can grab with a needlenose plier to fine adjust. Otherwise, you are stuck with the previous advice - bending the throttle tab. I have seen some tuners replace the screw with a socket type set screw - and use an Allen wrench on it - but I don't have that kind of patience.

After setting the primary throttle to its initial position, turn the mixture screws to their starting spot. Install the carb, , fill the bowls with fuel, start the engine, and successively adjust the secondary blade with the stop screw to make it stay running. The choke needs to be "off" - so it is the first order of business after the engine runs a bit.
 

 
 Steve Metzger       Tucson, Arizona

He used a vacuum gauge , got the piston positioned right so I feel it is timed right but we will see.
 

wont type c h e v r o l e t g u y.lol

The timing marks can be difficult to find.  A search of how to time using a vacuum gauge would give you an alternate method. I hadn't used it before I read about it on this site and it worked fine for me. Basically as I recall, adjust the distributor timing for max vacuum and back off a little.

Don

It sounds like you need to check a couple of things on that Holley.  It will require you to remove the carb and drain the fuel, and turn it over to check to see if the secondary throttle blades are open .020" showing on the idle circuit slot.  The idle on all Holleys except the four corner idle carbs should be controlled by the idle slot in the SECONDARY throttle bores.  Adjust them by the little screw on the secondary linkage to show .020", or by bending the linkage tab on the right rear corner of the base plate.  Then adjust the idle screws in until they gently bottom out, and back them out approximately 1 complete turn.  This should get the idle to settle down so you can fine tune it and set the idle speed with the accelerator arm adjusting screw.  Also, you should check the blades at wide open throttle (WOT) to see that they are 90* to the base plate, and adjust the linkage to accomplish.  Then lastly you need to check the accelerator pump for .015" clearance between the lever and linkage at WOT.  Should now idle in gear correctly.  Joe-JDC

JDC