I have a HEI Distributor GM upper and Ford lower.
I set the advance to about 35 degrees at 2500 Rpm
then checked the initial about 16 degrees at 700 rpm in park.
Is 16 ok for a stock 302 ( I read 10-12 is normal)
Have not driven yet after advancing. If it does not ping
I suppose it’s ok.
Wouldn’t my Distributor be calibrated at about 20 degrees.
Thanks
16 degrees of advance is OK, so long as you do not have any evidence of knocking under load. I ran my 289 4V non-HiPo at 16 degrees of advance without issue. Each engine seems to have its own “personality” or individuality when it comes to timing.
I meant to say 35-36 degrees total advanced at about 2500 rpm and 16 degrees initial at (Idle)about 700 rpm in park.
And is 2500 rpm about right?
I took a vacuum check at the manifold …steady…(17½") of vacuum. Never ran this smooth when idle
advance was 6 degrees. The Carb port to Dist line doesn’t read until you crack open the throttle.
I ordered a Actron CP7519 Timing Advance Analyzer to recheck advanced total timing.
Now I’m anxious to drive it after I re-test.
From memory 36 total sounds right. Seems today’s gas is OK w/more initial advance. Time for a ROAD TEST 
The amount of advance you need really depends a lot on what heads and cam you’re running, because your burn speed and dynamic compression determine when peak cylinder pressure happens.
Good heads need less advance, slow burning heads need more. A cam without much overlap will build higher pressure in the chamber sooner, so it will want less advance.
If you intend to drive on the street, you definitely want vacuum advance. Otherwise, you’re forced into a bad compromise between what the engine wants to idle and cruise smoothly, and what it wants for wide open throttle.
With high manifold vacuum, the fuel/air mix doesn’t light off very fast. It needs a spark well before the piston gets to the top of its travel, so peak pressure happens sometime around 12 degrees after TDC. If you tune the car to idle flawlessly without vac advance, then as soon as you’re filling the combustion chamber with LOTS of fuel and air, your engine will be trying to squash multiple strong flame fronts into the combustion chamber, creating peak pressure way too early. Best case scenario? You get ping and sluggish response. Worst case, you bend rods, crush bearings, break pistons. But that usually won’t happen on the low end, because your engine pulls through to higher RPMs where the peak power happens. That’s why peak mechanical timing is considered much more important than your timing at idle, all things considered. Breaking parts is obviously worse than annoying rattles and sluggish performance - but why not have them BOTH set right?
With vac advance, you can set mechanical timing to something a bit more conservative, like 8-12 degrees, and then the vac advance can pulls it up to something a lot closer to 18-20, letting your car idle smoothly and flawlessly. 20 degrees would be way too much for WOT obviously, but as soon as you step on it, manifold vac goes to 0, and vac advance lets timing fall straight back to 8-12 degrees, giving you exactly what the engine wants for all that fuel and air.
Peak timing could be as high as 40, if you’re running old-school heads and a raucous cam. Stockers usually like something more around 34, and just as an example, the fast-burning GT40P heads with an HO cam usually like only about 29 degrees total, if you can believe it.
Usually, you want to be all-in with timing at about 2800. 2500 might be just a little early.
Oh! And use MANIFOLD vacuum if you have a choice. Not timed/ported vacuum. If you want to open that can of worms, I’ll be glad to explain it, but be ready for a vigorous discussion, because even a lot of very good mechanics don’t understand this one. (geez I hope that didn’t sound too arrogant!)
I like this part,makes sense :“With vac advance, you can set mechanical timing to something a bit more conservative, like 8-12 degrees, and then the vac advance can pulls it up to something a lot closer to 18-20, letting your car idle smoothly and flawlessly. 20 degrees would be way too much for WOT obviously, but as soon as you step on it, manifold vac goes to 0, and vac advance lets timing fall straight back to 8-12 degrees, giving you exactly what the engine wants for all that fuel and air.”
“use MANIFOLD vacuum” I read that before, I’m using port and would like to hear the advantage of Manifold.
At 10 degrees not as smooth,should I back off to 10 and try to fine tune with air/fuel mixtures?
It’s running so smooth, I guess I’ll back it off to 12". And re-test at 2800. This is why I ask questions, to learn from those with experience.
Love to hear from you. Best regards Gene…btw Some own enough vehicles to have a car lot lol.
When you are setting initial (mechanical) timing, it WILL idle a bit rough, because you have the vac disconnected. You’re setting the timing for WOT, without the car actually BEING wide-open-throttle. However, when you hook up the vac advance, it should draw down and smooth right out - IF you are using manifold vacuum.
If you’re using timed vacuum, it will just continue to run rough, because you have no vac advance with the blades closed, using ported vacuum.
So what happens if you use ported vacuum and dial up the timing until it runs smooth? Well, think about it. Okay, you’re idling fine, on zero vacuum now. But as soon as you step on the gas a little bit, now your vacuum advance kicks in! Your car is now running way over-advanced. And guess what? It keeps running over-advanced as you begin to cruise down the highway at low RPMs too. You may not hear it pinging, because you’re probably running very light throttle. But you will be down on power, economy, and things in the combustion chamber will be getting HOT. It is very common for a car tuned this way to ‘diesel’ after you shut it off, because things in the combustion chamber are glowing, and even without a spark from the ignition, things light off anyway as fresh fuel and air continue to get fed to the cylinders.
There are two cases in which it is appropriate to use ported timing. One is for a concourse restoration of a '70s smog engine. Those cars typically had very retarded timing at idle, to deliberately dump extra unburnt air and fuel into the exhaust. It was intended to help the air injection system continue burning longer in the exhaust to clean up emissions, and to heat up the new catalytic converters that came later.
Of course, that was a really dumb idea, as burning the fuel inside the combustion chamber where it can actually do work is much better.
The other scenario where ported vacuum might be useful is for an engine that has so much overlap, the cam does not allow stable vacuum of any significant amount in the intake. In such a case, with the engine unable to idle properly at low RPMs, the vacuum in the manifold might be going as low as 6 lbs, but spiking to higher numbers. When you hook up a vacuum advance to that, the engine will surge as it cranks the timing up and down, making the idle problems even worse. A car in that state may not be able to idle at all, much less run right with an automatic transmission. Using ported vacuum for a car like that still has all the drawbacks and compromises listed above, but at least it doesn’t add to the ‘surging’ problem created by its savage cam. You’d still get the benefit of vacuum advance at part throttle, once you’re rolling and out of your idle circuit, but a lot of guys with the ‘hairy chested old-school’ approach to power just leave out vac advance completely, calling it a waste of time for a drag car like that.
Most modern racers find that vac advance helps even the meanest of engines, allowing crisper throttle response and tip-in, along with more controllable launches.
Generally speaking, ANY car that is ever driven on the street, where part throttle operation is used, will benefit from vacuum advance, and almost all of those will do best with manifold vacuum, if you want best driveability, economy, and power.
I blocked my port and use Manifold vacuum at 10 degrees Thanks a bunch and I believe you.
Going to set my 327" Corvette (29 Ford) the same way.
Just dawned on me,my 63 327" has points and “Remember, ignition timing is always set after you have adjusted your points.”
My 29 Ford has a 63 327 340 hp Corvette engine and a 67 Chevelle 396" Aluminum Powerglide (big planetary set used for racing / 5 high gear clutch plates.)
I installed a stock Chevy dist, how would I go about calibrating the Distributor?
Never mine:…Chevy V8 HEI Distributor Corvette Mechanical Tach Drive 283 327 396 427 SBC BBC should work!
In answer to the original question, you are fine where you are unless you have a true 10:1 or higher, in which case you should pay some mind to audible as well as secondary (i.e., aluminum specks on plug porcelain) signs of trouble.
I run your setup in my iron head 8.5:1 junk 302 - 20 crank degrees centrifugal in the distributor, and 16 on the crank. Mine’s not all in until 2800, but that’s mostly because that’s what I could get with springs for the Ford distributor I had on hand. No issue with 2500.
In 1968, Ford used ported vacuum, or manifold (triggered by that thermal switch up by the thermostat) if the engine ran hot. If you use manifold vacuum full time, you’ll see fuel economy go up because you’ll be running at about 50 total at light cruise!
Decided on 10 degrees for now,I’m running a different distributor,would that call for some Experimentation ?
HEI Ignition Distributor Just asking 
I just read this,now I am confused lol. quote:
“What is important is the total advance under any condition. At other than idle ported vacuum and manifold vacuum are the same. Ported vacuum means that the vacuum port is not revealed until the throttle plates are opened above idle.”
“On a Ford we like to run around 12 degrees initial advance at idle. Some a little more, some a little less. This means that we have 12 degrees of advance before the vacuum or mechanical advance kicks in. With ported vacuum there is no additional vacuum advance at idle. If you connect to manifold vacuum, you will get pretty close to maximum vacuum advance. This may cause you to have to reduce the initial advance setting on the distributor. When you hit the gas, the vacuum drops like a rock, and so does the vacuum advance, and just off idle you may end up with a flat spot from too little total advance. Fords were set up this way long before emissions became a concern.”
“If your car is not stock, if you are running a cam, a different distributor, or other mods, then you will probably get different results. Experimentation is not going to hurt, but the engineers at Ford were not just guessing about this stuff. Starting with what they thought was best is a good first pass. What makes experimentation worthwhile is that we are not using the same gas that our cars were originally designed for. In some cases, that means that we are running less initial advance, in order to limit total advance, than we would have run on 100+ octane leaded premium.”
“Ford had two different strategies for dealing with high engine temperatures at idle. On '68 Cougars (up to '70?) there is vacuum switch in the upper radiator outlet that switches idle vacuum to manifold vacuum when the engine gets hot. The idea is that higher RPMs will result in the fan pulling more air. On the Pantera they actually used manifold vacuum to retard the timing to slow down the engine to hopefully make less heat (electric fans).”
The other side of that story of course, is that the engines of that era used the same vacuum switch to normally run on ported vacuum, in order to dump still-burning exhaust into the exhaust manifold. They did this so that the air injection system could continue burning more air with the extra fuel in the exhaust, and later, to heat up the catalytic converters too.
It was a dumb idea even then, but car manufacturers were under pressure to find a way to reduce emissions, and at least they could say they were trying something.
You are far better running on manifold vacuum full time, and even if you’re environmentally conscious, it makes sense to tune your engine so it burns everything in the combustion chamber, not the tailpipe. That way the burning fuel is doing work, not just roasting your mufflers.
“Slowing the engine down” by retarding timing in the Pantera was dumb too. It would put less heat in the coolant, but all the still-burning fuel in the headers wouldn’t do that cramped engine compartment any favors!
I don’t have air injection system, so I’m sticking with 10 degrees and manifold vacuum. You sold me the first time, then I was puzzled lol. …my 2 ¢
Didn’t mean to add to the confusion. =) Those old smog motors were pretty crazy. It’s hard to believe that anyone thought the stuff they were adding and changing was an ‘improvement’.
Hope your engine runs awesome when you get it all dialed in.