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1st time using timing gun -- basic questions (with pics!)
Almost have my 396 dialed in, but I have small question.
I'm setting my idle to 750 RPM.
I put the gun at 0 degrees, my TDC line on my balancer should read even with the 0 mark on the timing tab.
They say these should be set to 35 or 36 degrees when the car is at 3k RPM... So once again, I want the TDC on my balancer to come to the 0 on my timing tab. Got it...
But now, since I adjusted the distributor, the advance at idle will no longer be 0 on the balancer and 0 at the timing tab, it should be something else... I read the idle advance on a 396 should be anywhere from 4 degrees to 14 degrees (depending on who you're talking to). Do I set this by putting the car back to idle and setting my gun to let's say 8 degrees? But once again, turning the distributor will affect my reading at 3k rpm... Or do I just set it at 3k rpm and I get what I get at idle?
Last question, when do I use the rest of the timing marks on the timing tab? After setting the 3k rpm timing, do I switch my gun back to 0, and let it idle, and the TDC mark on the balancer is now compared to the timing tab mark to tell me my advance at idle?
I'm a laptop tuner, this is my 1st time using a timing gun and marks, so sorry for the n00b questions! Thanks!!
first off, vacuum advance unhooked. light set at 0. start car. set timing to about 10 degrees on the timing tab. then turn the degree dial to 10 and see if mark goes to 0. now set dial to 36 degrees rev engine NOT to 3000, but until you see the timing mark stop advancing. it may hit full mechanical advance anywhere from 2500 to 5000 rpm. be sure you see it stop advancing. if you set it at 36 degrees at 3000 and it goes 5 degrees farther at 5000, you are advanced enough to burn pistons at full throttle. you want to maximize power at full throttle without doing damage to your engine. now, you have 36 degrees at full throttle. go back to idle and see what you have for timing. probably 12 to 18 degrees. hook up vacuum. see how much it climbs. probably 10 or 12 degrees more. idle timing is for emissions. it has to be down around 6 with no vacuum (vac hooked to ported port) for emissions test. it will idle far better where it is set at 12 to 18 with vacuum raising it more. you can get fancy and get adjustable vacuum advance can and mech advance bushings and springs to change the amount of vac and mech advance the distributor will give you, but before you do that email Lars v8fastcars@msn.com for his timing papers. i have an old version. he doesn't like others forwarding his papers to people. makes him more confident there is not a set of his numbers out there somebody decided to alter.
first off, vacuum advance unhooked. light set at 0. start car. set timing to about 10 degrees on the timing tab. then turn the degree dial to 10 and see if mark goes to 0. now set dial to 36 degrees rev engine NOT to 3000, but until you see the timing mark stop advancing.
^^ and the goal is to get my TDC mark on the balancer to be at the 0 mark on my timing tab by time it stops advancing?
it may hit full mechanical advance anywhere from 2500 to 5000 rpm. be sure you see it stop advancing. if you set it at 36 degrees at 3000 and it goes 5 degrees farther at 5000, you are advanced enough to burn pistons at full throttle. you want to maximize power at full throttle without doing damage to your engine. now, you have 36 degrees at full throttle.
go back to idle and see what you have for timing.
^^ to do this, am I setting my timing gun to 0, and looking at the TDC line on my balancer compared to the marks on the timing tab?
probably 12 to 18 degrees. hook up vacuum. see how much it climbs. probably 10 or 12 degrees more. idle timing is for emissions. it has to be down around 6 with no vacuum (vac hooked to ported port) for emissions test. it will idle far better where it is set at 12 to 18 with vacuum raising it more. you can get fancy and get adjustable vacuum advance can and mech advance bushings and springs to change the amount of vac and mech advance the distributor will give you, but before you do that email Lars v8fastcars@msn.com for his timing papers. i have an old version. he doesn't like others forwarding his papers to people. makes him more confident there is not a set of his numbers out there somebody decided to alter.
Ok so I watched a few more videos, I think I can answer my own questions, so just a verification that I'm right.
Everything depends on the balancer TDC and the 0 mark on the timing tab:
If I set my gun to 8 degrees, I want the TDC mark to align with the 0 on the tab.
Same with if I set my gun to 36 degrees, when I rev and it advances, I again want my mark to align with the 0 on the tab.
If I ever put my gun back to 0, my mark would (theoretically) line up with the 8 on the timing tab (idle), and if I change the gun back to 8 degrees, the mark would again align with the 0 on the tab. So instead of relying on the tab, you moreso rely on the gun to show you what the advance is when the mark and the tab are both at 0.
Set the mechanical advance at max (shoot for 36 degrees at 2500-3000 rpm). Limit the vacuum to no more than 16 degrees. Connect the vacuum advance to a full time (NOT ported) source.
The above procedure to use to set timing will give you a baseline setting only. Disconnect the vacuum advance canister (and plug the vacuum leak)...set your timing gun at 36 degrees....point the gun at the tab and rev the engine up until the mark on the balancer stops advancing as you rev higher. The engine is at the "top of the curve" if it does not advance any higher as you go higher in RPM. You can set the timing at 36 degrees while at the top of the curve and lock the distributor down. Double check your setting is right (36 degrees at the top) and then reconnect the vacuum hose. Ignore the initial setting for now. This is about all you can do at this point.
At some point in the future, we would want to recurve the entire ignition calibration. That requires physical modifications to the distributor. Lars has a paper on it he will email you if you decide to do it.
You can do everything with the zero marks and a dialback light (like an Innova 5568). Or you can use the timing tape shown in the video. Hopefully seeing it in action helps.
You can do everything with the zero marks and a dialback light (like an Innova 5568). Or you can use the timing tape shown in the video. Hopefully seeing it in action helps.
Yepp, watched the video...and like 20 others haha. But I'm a question asker just so I don't assume I'm taking in the info correctly and end up with a disaster!!
I think I got it now though! The concept of the numbers on the light vs the tab marks was the only thing really confusing me
I ended up dialing it in at roughly 2800 rpm to 36 degrees.... At idle, around 750 rpm, the timing is roughly 13 or so degrees.
Question, is it normal for the pass side of the engine to be a bit hotter than the driver side? Also, I have side pipes and the sound/lope of the exhaust sounds different from side to side as well. All normal? Hopefully...
i assume it stops advancing at 2800? you MAY want to go with slightly stiffer springs. hotter on the right? exhaust manifolds or headers with the sidepipes? is the heat riser still installed if exhaust manifolds? make sure it is open. best way is to remove it. second best is to remove the flapper. 3rd is to wire it open.
Ok so I watched a few more videos, I think I can answer my own questions, so just a verification that I'm right.
Everything depends on the balancer TDC and the 0 mark on the timing tab:
If I set my gun to 8 degrees, I want the TDC mark to align with the 0 on the tab.
Same with if I set my gun to 36 degrees, when I rev and it advances, I again want my mark to align with the 0 on the tab.
If I ever put my gun back to 0, my mark would (theoretically) line up with the 8 on the timing tab (idle), and if I change the gun back to 8 degrees, the mark would again align with the 0 on the tab. So instead of relying on the tab, you moreso rely on the gun to show you what the advance is when the mark and the tab are both at 0.
Sound about right?
Yes, this sounds like you are understanding it correctly. You are either setting the gun to zero and reading the timing degrees off the tab's scale or you're setting the gun to the desired degrees and adjusting the engine so the mark is at 0 on the tab.
I like to do both as a way of checking the accuracy of the light. If idle advance is at 12-14, set at 0 and read the tab. Then turn the dial until reading drops to 0 and see if dial says same reading u got the other way. Obviously won’t work at 36 degrees.
Last edited by derekderek; Sep 6, 2022 at 12:50 PM.
I ended up dialing it in at roughly 2800 rpm to 36 degrees.... At idle, around 750 rpm, the timing is roughly 13 or so degrees.
Question, is it normal for the pass side of the engine to be a bit hotter than the driver side? Also, I have side pipes and the sound/lope of the exhaust sounds different from side to side as well. All normal? Hopefully...
if you are using the stock advance springs they are too stiff to obtain maximum advance at 2.8k to 3k rpm. You need a Mr. Gasket 928G spring kit. You need to install the metal advance bushing stop in the kit to replace the original nylon bushing if it is still there. You should try one silver and one gold spring or two gold springs to achieve your maximum advance at 3k rpm.
i assume it stops advancing at 2800? you MAY want to go with slightly stiffer springs. hotter on the right? exhaust manifolds or headers with the sidepipes? is the heat riser still installed if exhaust manifolds? make sure it is open. best way is to remove it. second best is to remove the flapper. 3rd is to wire it open.
It stops at 2800. I readjusted my dwell to 30ish, and reset the timing... Idle is now 15 or 16 degrees. Still gets to about 36 degrees at 2800rpm.
I'll look into the springs.
And yeah it's hotter on the passenger side. Side pipes. The heads don't have the heat riser but I got the gasket that blocks it off
Originally Posted by derekderek
I like to do both as a way of checking the accuracy of the light. If adle advance is at 12-14, set at 0 and read the tab. Then turn the dial untim reading drops to 0 and see if dial says same reading u got the other way. Obviously won’t work at 36 degrees.
That's pretty much what I did. Checked it at 0 on the gun and 12 on the tab (it's now set to about 15)
Originally Posted by MelWff
if you are using the stock advance springs they are too stiff to obtain maximum advance at 2.8k to 3k rpm. You need a Mr. Gasket 928G spring kit. You need to install the metal advance bushing stop in the kit to replace the original nylon bushing if it is still there. You should try one silver and one gold spring or two gold springs to achieve your maximum advance at 3k rpm.
What would happen (negative side effects or symptoms) if I never replaced them?
It stops at 2800. I readjusted my dwell to 30ish, and reset the timing... Idle is now 15 or 16 degrees. Still gets to about 36 degrees at 2800rpm.
I'll look into the springs.
And yeah it's hotter on the passenger side. Side pipes. The heads don't have the heat riser but I got the gasket that blocks it off
That's pretty much what I did. Checked it at 0 on the gun and 12 on the tab (it's now set to about 15)
What would happen (negative side effects or symptoms) if I never replaced them?
it would continue to advance beyond 3k rpm resulting in too much advance. Again this is with stock springs, somebody may have already changed them.
45 year old springs tend to weaken with age. what will happen if it advances more to 3500 or so? nothing, really. you just have to be SURE it is advanced all the way.so you are not running 42 or more degrees at full throttle. that is when too much advance will start burning pistons along with the gasoline.
45 year old springs tend to weaken with age. what will happen if it advances more to 3500 or so? nothing, really. you just have to be SURE it is advanced all the way.so you are not running 42 or more degrees at full throttle. that is when too much advance will start burning pistons along with the gasoline.
It's a new distributor, so I'm going to assume they aren't 45yrs old haha
Yeah I ran it up to about 2800 and set it, then a little past. Probably up to like 3000 3100 or so... I mean is there ever a situation where it would pause at 3k but pick back up again at like 3400?
I'd assume that if base idle is set at 12-16 that higher rpm would be (generally) ok? If my base was something like 22, that would give it more of a chance to be too aggressive at higher rpms?
It's a new distributor, so I'm going to assume they aren't 45yrs old haha
Yeah I ran it up to about 2800 and set it, then a little past. Probably up to like 3000 3100 or so... I mean is there ever a situation where it would pause at 3k but pick back up again at like 3400?
I'd assume that if base idle is set at 12-16 that higher rpm would be (generally) ok? If my base was something like 22, that would give it more of a chance to be too aggressive at higher rpms?
remove one spring and recheck total advance to confirm its not over advancing.
remove one spring and recheck total advance to confirm its not over advancing.
So I just read up on the springs. So basically you're saying the stock springs could be too tight and the centrifugal force at 2800 rpm may not be enough to get full advance, but by 3400 it could be enough, and by that point my timing would be at like 40 degrees... Gotcha!
So I just read up on the springs. So basically you're saying the stock springs could be too tight and the centrifugal force at 2800 rpm may not be enough to get full advance, but by 3400 it could be enough, and by that point my timing would be at like 40 degrees... Gotcha!
1st time using timing gun -- basic questions (with pics!)
