Some of you may get annoyed because i have brought this subject up before but i want to fully understand this once and for all. The engine is a 360 magnum mopar electronic ignition with the mopar vaccume advance distributer. I un plugged the vaccume advance from the carburetor and plugged it off and it is plugged to the timed vaccume port on the edelbrock carb wich is the passenger side vaccume port. Anyways the timing light i have is a dial back timing light, my balancer has a tab on it that lights up with the timing light so you can clearly see it with the light on it, that eliminates the need for me to use timing tape or anything like that. I plugged the vaccume advance hose off started the engine and i set the timing at 10 degrees while at an idle, then i had my friend get in it and hold the gas steady at 3000 rpm and i set my dial back timing light at 35 and i shined the light down on it and it was up higher around 42 so i climbed up there turned the distributer clock wise a little bit got back down shined it on it and it was dead on at 35 on my timing light. I had my friend let go of the gas and i hooked the vaccume advance hose back up and set the idle opn the carburetor. What is my total timing? this is where it gets confusing to me, i set the initial idle timing at 10 degrees and at 3000 rpm its at 35 degrees so does that mean my total timing is 45? Does this sound about right for a mild 360 I gotta say it sounds pretty good at 10 degrees initial at idle and 35 degrees at 3000 rp. I am just trying to understand this once and for all and would like to know if i have the timing in the right ball park?
questions on timing an engine
- Thread starter pjc360
- Start date
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Total is what you see at 3000 rpm. The 10 degrees initial adds itself to the mechanical to become total @ 3000. The initial you change by turning the distributor and the total and the advance rate you can change by the springs and weights in the distributor. There are some guys here on FABO that really know how to modify distributors. I hope they post here. It sounds like you are close though. I would advance the initial to 13 or 14 as long as you don't have ping problems. I think the optimum total is 34 degrees. (Help me out here guys) tmm
You had your initial at 10*, then 42*at 3000. When you turned the distributor to get it back to 35* you changed your initial. Check it again, I'll bet it's not at 10* anymore.
What you need to do is get your initial set at whatever initial you want. I have mine set at 16*. Then to get the mechanical you will have to limit it inside the distributor it self (brazing the slots is one option) to keep the plate from turning as far as it does now, then if needed you can slowly file some of it away to get the desired mechanical. After that you can put lighter springs in 1 spring or a combination of lighter springs to get your mechanical to come in at the desired RPM. I have mine all in by 2500.
You can't just turn the dizzy to get total because that changes your initial.
What you need to do is get your initial set at whatever initial you want. I have mine set at 16*. Then to get the mechanical you will have to limit it inside the distributor it self (brazing the slots is one option) to keep the plate from turning as far as it does now, then if needed you can slowly file some of it away to get the desired mechanical. After that you can put lighter springs in 1 spring or a combination of lighter springs to get your mechanical to come in at the desired RPM. I have mine all in by 2500.
You can't just turn the dizzy to get total because that changes your initial.
So does that mean since i have it set at 35 at 3000rpm with vaccume advance plugged off that my total timing is 35 degrees? and i can not advance my distributer past 10 degrees. it does not turn any further. I think my old man installed the distributer that way, he knew alot about mopars and specially knew alot about this engine because it was his engine before i got it, i cant ask him about the timing because he passed away a year and a half ago.
67Dart273
Well-Known Member
FIRST until you prove it is accurate, there is no reason in my opinion, to trust "dial up" timing lights. In a previous life, I sold parts, and part of our service was to send tach/ dwell/ timing/ etc instruments in for rebuild I've seen a number of "dial up" lights that were not accurate.
SECOND Get/ make a piston stop and check your timing marks.
THIRD I still say either degree your balancer or buy the correct size timing tape
TIMING
"TOTAL" timing is the ADDED TOTAL of
1 INTITIAL timing set at idle, BEFORE either vacuum or mechanical kicks in
2 The amount of mechanical advance. If you READ on the timing marks, what the timing IS at HIGH RPM, then you HAVE at that point the TOTAL of INITIAL + MECHANICAL
3 For the true figure of TOTAL timing, you must also add the amount of vacuum advance. IF YOU READ this at high vacuum (simulated cruise) RPM, than you HAVE the TOTAL of the THREE right there
So if you set INITIAL, and you KNOW "how much" is "in" the distributor mechanical, you can ADD the 10 (or whatever) INITIAL to "what you know" is in the distributor, which might be 22-24* for a performance curve, and that gives you a TOTAL of INITIAL + MECHANICAL of 10 + 24 (say) for 34 TOTAL
BUT IF YOU ALSO use vacuum, and you have, say, a 15* "can" then you ALSO must add the amount of vacuum to the first two, for a TOTAL of the three of 49 (in this fanciful case)
ALSO BE AWARE that many books and service manual specify DISTRIBUTOR degrees, so you must DOUBLE that amount to get CRANK degrees
I ALWAYS "talk" (because I think) in "CRANK" degrees.
It is starting to sound like you have a LONG SLOW smog type advance
DO NOT GET HUNG UP on 3000 RPM. You MUST rev the engine to a high (but safe) RPM to be SURE that the mechanical is "all in." If you are concerned about doing this, simply unhook the fan belt long enough to check the timing, so the fan and alternator are stopped.
SECOND Get/ make a piston stop and check your timing marks.
THIRD I still say either degree your balancer or buy the correct size timing tape
TIMING
"TOTAL" timing is the ADDED TOTAL of
1 INTITIAL timing set at idle, BEFORE either vacuum or mechanical kicks in
2 The amount of mechanical advance. If you READ on the timing marks, what the timing IS at HIGH RPM, then you HAVE at that point the TOTAL of INITIAL + MECHANICAL
3 For the true figure of TOTAL timing, you must also add the amount of vacuum advance. IF YOU READ this at high vacuum (simulated cruise) RPM, than you HAVE the TOTAL of the THREE right there
So if you set INITIAL, and you KNOW "how much" is "in" the distributor mechanical, you can ADD the 10 (or whatever) INITIAL to "what you know" is in the distributor, which might be 22-24* for a performance curve, and that gives you a TOTAL of INITIAL + MECHANICAL of 10 + 24 (say) for 34 TOTAL
BUT IF YOU ALSO use vacuum, and you have, say, a 15* "can" then you ALSO must add the amount of vacuum to the first two, for a TOTAL of the three of 49 (in this fanciful case)
ALSO BE AWARE that many books and service manual specify DISTRIBUTOR degrees, so you must DOUBLE that amount to get CRANK degrees
I ALWAYS "talk" (because I think) in "CRANK" degrees.
It is starting to sound like you have a LONG SLOW smog type advance
DO NOT GET HUNG UP on 3000 RPM. You MUST rev the engine to a high (but safe) RPM to be SURE that the mechanical is "all in." If you are concerned about doing this, simply unhook the fan belt long enough to check the timing, so the fan and alternator are stopped.
OK i understand that, so should i jst leave it the hell alone? i set it at 10 degrees initial then reved it up to 3000 rpm and set it at 35, even tho that changed my initial timing it seems to run pretty darn good. i dont hear any pinging and no popping out the exhaust.
The timing light better work its brand new and it cost 150 bucks. Maybe i should i bring it to someone who knows more about it then i do and have them show me what to do, but i dont think the timing is off at all, it runs great so i might just leave it alone as long as it sounds like im in the right ball park to you guys i'll just leave it alone for now.
No, as I said when you backed off on the distributor to drop from 42 to 35 you changed your initial. I bet your initial is back down around 5-6 degrees.
As 67 said, your initial plus your mechanical is your total.
If it's running good then most definitely leave it where it's at. Take some time to read up on it. I know how frustrating it can be, I had a hard time getting my head around it too.
67Dart273
Well-Known Member
The only right way to do this is either obtain a performance distributor, or modify the one you have.
If you can braze or gas weld you can do this. I'll look if you are interested, somewhere there is a chart that relates the advance weight slot length to no of degrees mechanical. Then just buy a "spring kit" and get to work. You may have to tear the dist. down a few times, but I'll guarantee you that when you are done, you will KNOW how to time an engine, and how to drop the dist. in "right the first time."
A "cheap" fix is to open the dist. and pull the heavy spring OFF. Then "power time" the engine for 35* or so at high RPM.
.......DUP!!................here it is
Dimensions for Mopar distributor slots, in DISTRIBUTOR degrees, DOUBLE these for CRANK degrees
Modifying advance slots
degrees / slot size
6.............. .340
7................355
8................375
9................390
10...............405
11.5 ...........420
12...............435
13...............445
14...............460
15...............475
16...............490
17...............505
18...............520
If you can braze or gas weld you can do this. I'll look if you are interested, somewhere there is a chart that relates the advance weight slot length to no of degrees mechanical. Then just buy a "spring kit" and get to work. You may have to tear the dist. down a few times, but I'll guarantee you that when you are done, you will KNOW how to time an engine, and how to drop the dist. in "right the first time."
A "cheap" fix is to open the dist. and pull the heavy spring OFF. Then "power time" the engine for 35* or so at high RPM.
.......DUP!!................here it is
Dimensions for Mopar distributor slots, in DISTRIBUTOR degrees, DOUBLE these for CRANK degrees
Modifying advance slots
degrees / slot size
6.............. .340
7................355
8................375
9................390
10...............405
11.5 ...........420
12...............435
13...............445
14...............460
15...............475
16...............490
17...............505
18...............520
EXACTLY!
Bring the rpm up until it stops advancing. Any other reading at a lower rpm is absolutely irrelevent.
If you found where the engine likes initial, any time you dial back the total timing by turning the distributor, you've reduced initial timing. You need to get into the distributor and adjust/reduce the mechanical advance.
Good thing you guys chimed in. I must have been gone the day they taught timing advance theory in school.. LOL
So what would be considered a high performance distributer? i thought the mopar distributers were hi perf distributers? wich distributers seem to work best with the small block magnums? msd, mallory? i was looking at the dui ignition but not the original dui ignition the tri pod one the smaller distributer because its a 12 volt ignition system.
And yes it does seem to be running good where its at now, its running about 8 degrees initial and 35 degrees mechanical. tommarrow i might advance it all the way to 12 degrees initial and set it at 34 degrees at 3000 rpm and see how she runs there. or should i just leave it alone? I been trying to figure out why i cant advance it past 12 degrees initial? the vaccume canister is not hitting anything nothing is in its way it just does not turn any further. With it turned all the way i checked it and it was at 12 degrees initial. Is it possible my old man put it in this way so that it couldnt be advanced past 12 degrees?
The only thing i can think of is that my dad put it in this way so that it could not be advanced past 12 degrees initial and i know he did some work on the distributer i just wish i knew what hje did seems to me like he did some spring changing, problem is he dropped this engine in the truck but did not have the wiring finished before he passed away, this truck was just his weekend mess around side project and i picked up where he left off when he passed away and i got the wiring done got it started and running and now im basically just trying to fine tune it ignition wise, what would you guys suggest doing? should i buy a hi perf distributer or stick with what i got and leave it alone since its running well? i hammer on the gas and it sucks you back in the seat pretty good, i cant hear any pinging its not running hot i dont hear any popping out the exhaust im guessing its gotta be pretty close to dead on or somehwat close. Like i said i set it at 10 degrees initial reved up to about 3000 rpm with vaccume advance plugged off and i dialed it back to 35 degrees then i plugged the vaccume advance hose back in. Should i advance it all the way to 12 degrees while at an idle and go to 3000 rpm and dial it back down to 35 degrees? what would you guys set at with what i have to work with wich is just a dial back timing light? i just wanna know what i should set it with what i got for now and later on down the road i'll pick up a better distributer.
Disclaimer: I'm ultra-tired, so if I'm turned around on anything, someone will probably find it and steer you right.
If you're setting it to 35 degrees when it's fully advanced (3500 or whatever it ends up being due to springs and such), the initial doesn't matter. The difference between initial and total is determined by movement of the mechanical advance mechanism.
Mechanical advance works as follows: The springs and weights work together to determine the rate (what RPM it's done advancing) and amount (length of the slots).
Example: If you want to set initial advance at (let's say) 15 degrees with a total of 35 degrees, the slots would need to be modified (to 0.405" (I think)) to give 20 degrees of mechanical advance. The total is all in the length of those slots.
Note: Everything above is in crankshaft degrees. Divide by two for distributor degrees.
It seems kinda strange until you pull it apart, see how it all works together and have that "Aha!" moment. It'll pop into focus soon.
If you're setting it to 35 degrees when it's fully advanced (3500 or whatever it ends up being due to springs and such), the initial doesn't matter. The difference between initial and total is determined by movement of the mechanical advance mechanism.
Mechanical advance works as follows: The springs and weights work together to determine the rate (what RPM it's done advancing) and amount (length of the slots).
Example: If you want to set initial advance at (let's say) 15 degrees with a total of 35 degrees, the slots would need to be modified (to 0.405" (I think)) to give 20 degrees of mechanical advance. The total is all in the length of those slots.
Note: Everything above is in crankshaft degrees. Divide by two for distributor degrees.
It seems kinda strange until you pull it apart, see how it all works together and have that "Aha!" moment. It'll pop into focus soon.
Johnny Dart
Well-Known Member
Set your TOTAL timing to 34-36 degrees.
If it doesn't ping when driving,your done.
Now go have a burger.
If it doesn't ping when driving,your done.
Now go have a burger.
So i should just set the rpm at 3000 set the timing at 35 degrees on my timing light and just leave the initial timing wherever it lands after that? And the distributer i have is the mopar vaccume advance distributer, it came with the engine when purchased from mopar i thought i had read these distributers have a fast curve in them? and that it all comes in around 2000 to 2500 rpm? i'm sure somone here knows when its done advancing and all that?
Yes ok but please explain how to set my total timing at 34 to 36 degrees? by saying total timing do you mean reving it up to around 2500 to 3000 rpm and setting it at 35 degrees with my timing light? because thats what i did, is that what you mean by setting total timing?
Total timing method is not the best way to set up a car driven on the street.
What is the best way then? somone should explain to me step by step on how i should go about timing this engine with what i have. The engine is a crate 360 magnum i had it dynoed recently its putting out 319 horsepower at 4750 rpm and 424 ft lbs of torque at 4200 rpm. The distributer is a mopar distributer it came with the engine its got vaccume advance on it, i have the vaccume advance plugged into the timed port on my edelbrock carburetor the passenger side port. The timing light i have is a dial back timing light brand new only been used a few times. If somone could say number 1 you do this number 2 you do that i think i would get it alot easier. I have read some people say dont get set on a certain rpm but the directions i read said to set the initial at whatever idles best then rev the engine up to 2500 to 3000 rpm and keep that rpm steady and set it at 35 degrees at that rpm and then your done. I read that on a mopar web site of some kind so thats what iu did and it seems to be running good i dont hear any pinging or popping and i have good throttle response. i just want to know how to perform just a simple basic quick timing job on my engine doesnt have to be dead on just as long as its close enought to where its not going to pop or ping.
67Dart273
Well-Known Member
I'm getting the feeling you have read nothing of what some of us posted. When crackedback says something, you might listen.
So I'm gonna say this just one more time
The RIGHT way to do this is either recurve your distributor to a more performance oriented curve, or buy an aftermarket performance distributor.
And LOSE the infatuation with 3000 RPM. YOU NEED to rev the engine up way past this to BE SURE it is not continuing to advance
So set the timing at 3K and at 35* if that's what kicks your cookie, then WATCHING the marks, REV it way up there to be sure it is "all in"
Then idle the engine WAY down and see what the idle/ initial timing ENDS UP to be. THIS WILL TELL YOU if the dist. curve is "way too long" or not. That is, if you set high RPM at 35, and intitial ends up at 0-5*, then you have a long curve, and need to recurve the dist. for best performance.
You need to BUY a spring kit so you can SPEED UP the rate at which the advance operates.
OR you need to buy an aftermarket dist. which is already setup "to start" and probably has an ADJUSTABLE advance mechanism.
HERE is an article on one type of aftermarket, adjustable advance
http://www.moparts.org/Tech/Archive/elec/29.html
Here's a drawing of one type of adjustable advance:
And LOSE the idea that a dial up light is accurate. It might be. It might not be. I've had enough bad experiences with 'em that I don't use 'em.
So I'm gonna say this just one more time
The RIGHT way to do this is either recurve your distributor to a more performance oriented curve, or buy an aftermarket performance distributor.
And LOSE the infatuation with 3000 RPM. YOU NEED to rev the engine up way past this to BE SURE it is not continuing to advance
So set the timing at 3K and at 35* if that's what kicks your cookie, then WATCHING the marks, REV it way up there to be sure it is "all in"
Then idle the engine WAY down and see what the idle/ initial timing ENDS UP to be. THIS WILL TELL YOU if the dist. curve is "way too long" or not. That is, if you set high RPM at 35, and intitial ends up at 0-5*, then you have a long curve, and need to recurve the dist. for best performance.
You need to BUY a spring kit so you can SPEED UP the rate at which the advance operates.
OR you need to buy an aftermarket dist. which is already setup "to start" and probably has an ADJUSTABLE advance mechanism.
HERE is an article on one type of aftermarket, adjustable advance
http://www.moparts.org/Tech/Archive/elec/29.html
Here's a drawing of one type of adjustable advance:
And LOSE the idea that a dial up light is accurate. It might be. It might not be. I've had enough bad experiences with 'em that I don't use 'em.
Nappa82
Well-Known Member
So what exactly are you trying to get at? You just said you got it working great but you need someone to tell you how???? Sorry you've confused a lot of us I think.
From what I see, you know how to time it (If its running good). So why do you still feel the need to mess with it? Accept the timing and move on. With time you will understand it in detail but its gonna take a while and a few more tries to get it. Its not something you can learn overnight. ALL engines are different and act different... Even the same model and hoses and everything there will be a difference.
10* initial on a mild 360 might run, bet it would idle cleaner, more vacuum, snappier response at 15-16*
Find the total number where it doesn't ping. Depending on heads, open chambers around 35-36 is usually OK with decent fuel.
Lets call initial 15 and total 35, so the mechanical advance in the distributor needs to be 20*. Sounds like yours may have more than 30* in it. 42 total - 10 initial = 32 mechanical (if you actually got to the end of the advance curve at 3K rpm). I've seen mopar distributors not fully advanced until 4000 rpm sometimes. That's why you MUST rev the engine to the point where it stops advancing, not some predetermined number.
Think of building a house. you don't build the roof before having a foundation and framing. Initial is the foundation on a street car, everything builds upon it. So find the initial the ENGINE wants, not some number you choose.
Having a total number is next, to do the mechanical advance. Then you can adjust the curve, how fast it comes in, with springs. Finally you have vacuum advance if you want to run it.
Others have covered this and it seems to come up a lot around here.
I'll say this, time it however you want. If it's a straight race car, total timing works OK. I don't even do my race cars total timing method anymore. Some methods work better than others.
Find the total number where it doesn't ping. Depending on heads, open chambers around 35-36 is usually OK with decent fuel.
Lets call initial 15 and total 35, so the mechanical advance in the distributor needs to be 20*. Sounds like yours may have more than 30* in it. 42 total - 10 initial = 32 mechanical (if you actually got to the end of the advance curve at 3K rpm). I've seen mopar distributors not fully advanced until 4000 rpm sometimes. That's why you MUST rev the engine to the point where it stops advancing, not some predetermined number.
Think of building a house. you don't build the roof before having a foundation and framing. Initial is the foundation on a street car, everything builds upon it. So find the initial the ENGINE wants, not some number you choose.
Having a total number is next, to do the mechanical advance. Then you can adjust the curve, how fast it comes in, with springs. Finally you have vacuum advance if you want to run it.
Others have covered this and it seems to come up a lot around here.
I'll say this, time it however you want. If it's a straight race car, total timing works OK. I don't even do my race cars total timing method anymore. Some methods work better than others.
Mad Dart
Nothing to see Here!
So the engine was Dyno'd and the Dyno Operator did not tell you where he set the timing at to get the numbers the engine put out?? WOW, that is weak.
Remember after you get the Ignition Timing all figured out, next would be the Carburetor.
Remember after you get the Ignition Timing all figured out, next would be the Carburetor.
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