Initial timing

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Stock initial timing spec is probably 4 degrees BTDC. But if you want to know for sure, go over to mymopar.com and download a factory service manual.
 
It's 2 BTDC for an auto trans car. Right out of a repair Manuel
 
roccodart440 said:
Set total to 38 and then check the initial. If it is 0BTDC or more you're good for a stock /6
Click to expand...
I don't know the engine year but the engine have the no tubes sparkplug,I think it's 76 and up,this engine has been change by the former owner,I have a point distributor since its in my 66 valiant
 
3 different dist auto ,manual and feather duster 3 different base timing dist number is important. Parts got mixed up all the time
 
Here's what you're gonna have to do. Get a timing light. Set the timing to 2 degrees at idle with the vacuum advance disconnected and that hose from the carburetor plugged. Now with the light on the balancer, run the engine up until you see the mechanical advance stop advancing. Subtract your 2 degree initial figure from "whatever" that total is. Say if the distributor stops advancing at 3500 RPM at 28 degrees, then you have 30 total. Understand? You're gonna have to do it that way, to see "which" distributor is in there and how much mechanical advance is in that distributor. My stock 170 ran its best at 12 degrees initial at idle, but I had to limit the total to 30 degrees. I tried 15 initial at idle, but it ran better at 12. If you have a way to limit the total to "around" 30 give or take, they usually perform better with more initial timing than the factory spec.......but "I" would see what's in the distributor FIRST. It appears it could be several different things, so you're gonna have to find out.
 
Do you know the initial timing for a 1976 225 slant 6? Takes time to look this stuff up,after that effort you tell us you have point distributor,waste of my time. If it is 76 engine what carb and number some carbs were manifold vacuum .that will affect timing
 
^^^^What he said^^^^

List out what this car has and what you are trying to accomplish.
There were some some small changes to the 225 in terms of cam and compression, which will slightly effect timing.
But if the engine was rebuilt, then those small changes are probably out the window anyway.

The big changes in initial timing relate to the emissions.
If you are using the original 1966 distributor then the timing curve is non-emissions (except California) and everything is simpler.

If the carb is a non-emissions carb, that's even better.

Bottom line is the distributor is the most important thing to know. if it was intended for initial at TDC and you set it at 10 BTC, it will have too much timing at 2000 rpm. And it was intended for 12 BTDC for a Feather duster engines and you set it at 5 BTC, it will be igniting little late and wasting energy at driving rpms.
So if you don't know this, then set it for a good start using the '66 specs, and then measure and plot the timing curve using a dialback light (or timing tape) and tach .
 
Mattax said:
^^^^What he said^^^^

List out what this car has and what you are trying to accomplish.
There were some some small changes to the 225 in terms of cam and compression, which will slightly effect timing.
But if the engine was rebuilt, then those small changes are probably out the window anyway.

The big changes in initial timing relate to the emissions.
If you are using the original 1966 distributor then the timing curve is non-emissions (except California) and everything is simpler.

If the carb is a non-emissions carb, that's even better.

Bottom line is the distributor is the most important thing to know. if it was intended for initial at TDC and you set it at 10 BTC, it will have too much timing at 2000 rpm. And it was intended for 12 BTDC for a Feather duster engines and you set it at 5 BTC, it will be igniting little late and wasting energy at driving rpms.
So if you don't know this, then set it for a good start using the '66 specs, and then measure and plot the timing curve using a dialback light (or timing tape) and tach .
Click to expand...
Exactly! That's why I suggested he put a light on it as I outlined Up there ^^^^ somewhere. He'll find out.
 
lemme add that if its a points distributor then it could be pre-smog, or it could be early CAP/CAS (smog) which had different specs nearly every year.

Download a 1966 Plymouth FSM.
The initial timing for a 225 should be set at slow idle, which should be 550 rpm with the headlights on.
1727017058871.png


If you can't get it to idle at 550, at least for the first iternation or two, get it as slow as you can to begin measuring timing vs. rpm.
With a dial back light or a hilly billy timing tape (marks) Measure timing up to at least 2000 rpm. Write it down and plot it. This is enough to see if its an emmissions or pre-emissions set up.
 
Mattax said:
^^^^What he said^^^^

List out what this car has and what you are trying to accomplish.
There were some some small changes to the 225 in terms of cam and compression, which will slightly effect timing.
But if the engine was rebuilt, then those small changes are probably out the window anyway.

The big changes in initial timing relate to the emissions.
If you are using the original 1966 distributor then the timing curve is non-emissions (except California) and everything is simpler.

If the carb is a non-emissions carb, that's even better.

Bottom line is the distributor is the most important thing to know. if it was intended for initial at TDC and you set it at 10 BTC, it will have too much timing at 2000 rpm. And it was intended for 12 BTDC for a Feather duster engines and you set it at 5 BTC, it will be igniting little late and wasting energy at driving rpms.
So if you don't know this, then set it for a good start using the '66 specs, and then measure and plot the timing curve using a dialback light (or timing tape) and tach .
Click to expand...
Hi,my distributor is the original 66,my engine is most recent Witt the small spark plug I set the timing at 8 degree and he run fine,he don't ping,I will try at 10 degree to see what happen,,,thank you
 
"ping" or gurgle is most likely to be noticed when the engine is fully heat soaked. It is obviously not ideal but only under full load (upper gears, full or near full throttle, will it cause severe damage.

8 degrees at 550 rpm? or 8 degrees at 800 rpm? The rpm can make a big difference.

For example, the distributors specs above allow advance to begin as low as 650 rpm and be as much a 5º advanced at 950 rpm.
 
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I hate to keep harping on this , but
Idle timing is nearly meaningless except as a means to an end.
The first time that Ignition timing is important is at Stall-rpm, and the Second is for Power timing. and Both times you gotta stay below detonation, with whatever fuel you are using.
Most times, to connect those two points, namely Stall and Power, you are gonna need a 2-stage curve, that is gonna begun at near 1000 rpm. But what the initial is chose to be, most often coincides with whatever it takes to generate that Stall-to Power timing line.
If you know the Stall-rpm, and you know what max Power-timing should be, you just connect those two, and the Idle Timing is then the fall out.
But, when yur done getting an Idle advance number, by fall-out, you still got to get away from a Tip-in sag, or a huge rpm-drop at N>D, which bangs the trans into gear.
So then, it can take a base-timing of anything from Zero Advance to say 12 degrees.
And in most cases it will take a two-stage curve, to not have too much timing at idle, which kills either the Transfer slot to Mixture screw fuel delivery ratio, or it bangs the trans.
The factory works that all out for you and gives the distributor a part number, that will have all the correct parts in it, and all you gotta do is consult the nice sticker they even put under the hood for you, and then everything will be peachy keen.
But here we are some 50 years later. Maybe the engine has been changed. maybe the distributor is not OEM, maybe the sticker is gone, whatever the case may be, and so, hey, we're on our own.
So what do you do?
Lemmee reiterate;
Idle-timing is as good as meaningless.
The short answer is set the Power-timing and just drive it, cuz at least it won't rattle to sudden-death.
So what is the max-timing number?
IDK, but I can tell you this, it is between 2 and maybe 3 degrees less than whatever causes the engine to detonate, on whatever octane gas is in the tank. and that's gonna be almost directly related to two things;
1) the cylinder pressure, and
2) the condition of the combustion chamber; be it temperate, shape, design, cleanliness, or the effing sparkplug sticking up into it.
If a man tells you 38* and you rattle the skirts into the oilpan, whose fault is that?
If a man tells you no, 34* is the maximum, and fuel economy drops to 10mpg, whose fault is that?
If another man says no, it's 30* but but at stall, the engine is gutless, whose fault is that?
IDK the magic number for your combo,
but I can almost guarantee you that if you set the Idle-Timing to whatever, it will be wrong EVERY where else, simply because of all the variables in play, between today and the day it left the factory.

I really am just trying to help.
 
moparcuda said:
I don't know the engine year but the engine have the no tubes sparkplug,I think it's 76 and up,this engine has been change by the former owner,I have a point distributor since its in my 66 valiant
Click to expand...

So all the verbiage about '76 emission controls and manuals and such does not apply. You've got an engine configured as in the '60s, with a '60s distributor.

Disconnect the vacuum advance hose at the distributor end. Stick a pencil in the end of the hose. Set the engine idle speed to about 700 rpm, and the basic timing to between 2-/12° and 5° BTDC. Reconnect the hose and readjust the idle speed as needed. All done.
 
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AJ/FormS said:
I hate to keep harping on this , but
Idle timing is nearly meaningless except as a means to an end.
The first time that Ignition timing is important is at Stall-rpm, and the Second is for Power timing. and Both times you gotta stay below detonation, with whatever fuel you are using.
Most times, to connect those two points, namely Stall and Power, you are gonna need a 2-stage curve, that is gonna begun at near 1000 rpm. But what the initial is chose to be, most often coincides with whatever it takes to generate that Stall-to Power timing line.
If you know the Stall-rpm, and you know what max Power-timing should be, you just connect those two, and the Idle Timing is then the fall out.
But, when yur done getting an Idle advance number, by fall-out, you still got to get away from a Tip-in sag, or a huge rpm-drop at N>D, which bangs the trans into gear.
So then, it can take a base-timing of anything from Zero Advance to say 12 degrees.
And in most cases it will take a two-stage curve, to not have too much timing at idle, which kills either the Transfer slot to Mixture screw fuel delivery ratio, or it bangs the trans.
The factory works that all out for you and gives the distributor a part number, that will have all the correct parts in it, and all you gotta do is consult the nice sticker they even put under the hood for you, and then everything will be peachy keen.
But here we are some 50 years later. Maybe the engine has been changed. maybe the distributor is not OEM, maybe the sticker is gone, whatever the case may be, and so, hey, we're on our own.
So what do you do?
Lemmee reiterate;
Idle-timing is as good as meaningless.
The short answer is set the Power-timing and just drive it, cuz at least it won't rattle to sudden-death.
So what is the max-timing number?
IDK, but I can tell you this, it is between 2 and maybe 3 degrees less than whatever causes the engine to detonate, on whatever octane gas is in the tank. and that's gonna be almost directly related to two things;
1) the cylinder pressure, and
2) the condition of the combustion chamber; be it temperate, shape, design, cleanliness, or the effing sparkplug sticking up into it.
If a man tells you 38* and you rattle the skirts into the oilpan, whose fault is that?
If a man tells you no, 34* is the maximum, and fuel economy drops to 10mpg, whose fault is that?
If another man says no, it's 30* but but at stall, the engine is gutless, whose fault is that?
IDK the magic number for your combo,
but I can almost guarantee you that if you set the Idle-Timing to whatever, it will be wrong EVERY where else, simply because of all the variables in play, between today and the day it left the factory.

I really am just trying to help.
Click to expand...


Converter stall speed and ignition timing are NOT related.
 
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