Timing

[Ironmike]

Well , I remember reading here someone said ALL ignition boxes retard timing at higher RPM. Didn't pay much attention to it, but maybe should have.

I decided to check mine before I fog the motor down for the winter and don't ya know, 35 Degrees locked, at around 4600 RPM it retards 3 or 4 degrees. Not ideal, since my shift light comes on at 6600. My ignition is a FAST box with rev limiter and built in 2 step. Trying to figure out a fix.

Forget telling me to put a curve in my distrib, and locked is no good..... I bought the bushing kit from 4 Seconds Flat, tried 3 or 4 different curves and my car with my engine just wants 35 degrees. Starts better, idles better and is quicker.

I'm wondering when this engine was on the dyno a few years ago, was HIS box retarding my timing also? If so I guess I'm ok, but it's been buggin' me.

Leave it alone or somehow correct it?

 

[PRH]

I set the total timing at the upper limit of the usable rpm range.

 

[RustyRatRod]

Why isn't it ideal? As RPM increases, so does cylinder pressure. I think a little retard at the top is generally a good thing. Not to mention, retarding timing helps top end power and it does it automatically. I don't give a CRAP what forum gurus say, those are FACTS.

 

[Ironmike]

Why isn't it ideal? As RPM increases, so does cylinder pressure. I think a little retard at the top is generally a good thing. Not to mention, retarding timing helps top end power and it does it automatically. I don't give a CRAP what forum gurus say, those are FACTS.

Makes sense, Rusty. I was LEANING that way, but I think I needed to hear it from someone else. Thanks, brutha!

 

[RustyRatRod]

Makes sense, Rusty. I was LEANING that way, but I think I needed to hear it from someone else. Thanks, brutha!

I mean, if your combo can stand to not have the retard, then great. But who would want to be pulling like a freight train toward the traps needing to dial back a few degrees and not do it? You'll never be able to hear the spark knock with all the other noise and by then it'd be too late. A "better safe than sorry" kinda thing.

 

[Newbomb Turk]

Makes sense, Rusty. I was LEANING that way, but I think I needed to hear it from someone else. Thanks, brutha!

Sorry, but thats exactly how it doesn’t work.

I don’t care what engine it is, it has maximum cylinder pressure at peak torque. Any rpm AFTER peak torque and the engine will want more timing, which is the exact opposite of what you are giving it.

This is why vacuum advance works. At low load, high vacuum the engine has very little cylinder fill. The molecules are not packed very tight so they burn slow. A slow burn makes heat way too late to do any good, and in fact will run exhaust gas temperatures right through the roof. So you use vacuum advance to add some timing at low load, high vacuum situations.

So let’s say you say you decide to leave it locked out. And you are retarding about 2 degrees per 1k rpm. So you time it at 6600 and you give it four more degrees.

What does that make your timing at peak torque? You just gave it four more degrees everywhere it did not retard. Can the engine tolerate 4 more degrees at peak torque? That’s a lot.

What does that make you do if the car slows down? Is it because it hated the timing at 6600 or didnt hate it everywhere else? Or did it want more timing at peak (the 4 degrees you just gave it) or did it want a bit more at 6600 and much less at peak torque?

These are some of the issues that crop up with locked out timing. You are fighting physics and you are compromising your timing everywhere except where you set the timing.

Anyone with a distributor machine and a couple of hours a can build a curve that will idle as good as you have and make more power everywhere. Plus the engine will be happier.

BTDT many times. I used to lock everything out until I learned how bad it is.

 

[RustyRatRod]

Sorry, but thats exactly how it doesn’t work.

I don’t care what engine it is, it has maximum cylinder pressure at peak torque. Any rpm AFTER peak torque and the engine will want more timing, which is the exact opposite of what you are giving it.

This is why vacuum advance works. At low load, high vacuum the engine has very little cylinder fill. The molecules are not packed very tight so they burn slow. A slow burn makes heat way too late to do any good, and in fact will run exhaust gas temperatures right through the roof. So you use vacuum advance to add some timing at low load, high vacuum situations.

So let’s say you say you decide to leave it locked out. And you are retarding about 2 degrees per 1k rpm. So you time it at 6600 and you give it four more degrees.

What does that make your timing at peak torque? You just gave it four more degrees everywhere it did not retard. Can the engine tolerate 4 more degrees at peak torque? That’s a lot.

What does that make you do if the car slows down? Is it because it hated the timing at 6600 or didnt hate it everywhere else? Or did it want more timing at peak (the 4 degrees you just gave it) or did it want a bit more at 6600 and much less at peak torque?

These are some of the issues that crop up with locked out timing. You are fighting physics and you are compromising your timing everywhere except where you set the timing.

Anyone with a distributor machine and a couple of hours a can build a curve that will idle as good as you have and make more power everywhere. Plus the engine will be happier.

BTDT many times. I used to lock everything out until I learned how bad it is.

I can agree to disgreee. I'm a big boy.

 

[Newbomb Turk]

I can agree to disgreee. I'm a big boy.

I know that lol.

 

[Newbomb Turk]

I can agree to disgreee. I'm a big boy.

If I can get my wife to do some of the filming (well most of it because I hate that) I will film my trash on the dyno showing how I develop a timing curve and how that affects power across the curve.

If I have to film it then that most likely won’t happen.

 

[RustyRatRod]

If I can get my wife to do some of the filming (well most of it because I hate that) I will film my trash on the dyno showing how I develop a timing curve and how that affects power across the curve.

If I have to film it then that most likely won’t happen.

I believe what you're saying.....even still at peak torque where compression is highest.....is that gonna be at 3000 RPM putt puttin around the street or 4500 plus charging for the lights? I know I would prefer "a little" retard on the other end. I would make up for the small power loss...if at all "somewhere else". I'd rather do that than damage a motor. Imma still tell your wife to whop you one though.

 

[Newbomb Turk]

I believe what you're saying.....even still at peak torque where compression is highest.....is that gonna be at 3000 RPM putt puttin around the street or 4500 plus charging for the lights? I know I would prefer "a little" retard on the other end. I would make up for the small power loss...if at all "somewhere else". I'd rather do that than damage a motor. Imma still tell your wife to whop you one though.

Don’t encourage her!

 

[RustyRatRod]

Don’t encourage her!

Will too!

 

[fishmens67]

Imma still tell your wife to whop you one though.

He needs it, whap, whap. lol

 

[Bewy]

If you are using a dist with a mag trigger, you will get some retard as rpm increases from distortion coming from the p/up coil. Only thinking out loud now, but I can see two areas coming from the timing light itself that could produce a retarded reading [ time lag ] The clamp that picks up the high voltage in the leads is a ferrite inductor; if it has a wire coil around it to amplify the signal, then that coil takes time to reach max current value. Also, the Xenon lamp in the timing light. Xenon is a gas; it requires an ionising voltage to ignite it & that is going to take time also.

 

[Illahe]

If you are using a dist with a mag trigger, you will get some retard as rpm increases from distortion coming from the p/up coil. Only thinking out loud now, but I can see two areas coming from the timing light itself that could produce a retarded reading [ time lag ] The clamp that picks up the high voltage in the leads is a ferrite inductor; if it has a wire coil around it to amplify the signal, then that coil takes time to reach max current value. Also, the Xenon lamp in the timing light. Xenon is a gas; it requires an ionising voltage to ignite it & that is going to take time also.

That’s a lot of science (physics(?)to take in, but it seems true. Thanks for the lesson!

 

[9secRR]

Sorry, but thats exactly how it doesn’t work.

I don’t care what engine it is, it has maximum cylinder pressure at peak torque. Any rpm AFTER peak torque and the engine will want more timing, which is the exact opposite of what you are giving it.

This is why vacuum advance works. At low load, high vacuum the engine has very little cylinder fill. The molecules are not packed very tight so they burn slow. A slow burn makes heat way too late to do any good, and in fact will run exhaust gas temperatures right through the roof. So you use vacuum advance to add some timing at low load, high vacuum situations.

So let’s say you say you decide to leave it locked out. And you are retarding about 2 degrees per 1k rpm. So you time it at 6600 and you give it four more degrees.

What does that make your timing at peak torque? You just gave it four more degrees everywhere it did not retard. Can the engine tolerate 4 more degrees at peak torque? That’s a lot.

What does that make you do if the car slows down? Is it because it hated the timing at 6600 or didnt hate it everywhere else? Or did it want more timing at peak (the 4 degrees you just gave it) or did it want a bit more at 6600 and much less at peak torque?

These are some of the issues that crop up with locked out timing. You are fighting physics and you are compromising your timing everywhere except where you set the timing.

Anyone with a distributor machine and a couple of hours a can build a curve that will idle as good as you have and make more power everywhere. Plus the engine will be happier.

BTDT many times. I used to lock everything out until I learned how bad it is.

have you done back to back runs down the track from locked timing to a timing curve to see if it works down the track? i would like to see the results if you have done this testing. i like to see timeslips as proof of what works and what doesn't.

timing is an interesting topic, more data the better.

 

[Newbomb Turk]

have you done back to back runs down the track from locked timing to a timing curve to see if it works down the track? i would like to see the results if you have done this testing. i like to see timeslips as proof of what works and what doesn't.

timing is an interesting topic, more data the better.

Not on drag car stuff yet. But several circle track cars. They all picked up.

I also have to find someone who is willing to test it at the track. Honestly, most guys don’t want to test. And if they do it’s make a change, make a pass and if it doesn’t pick up a half a second they want to go back to what they had.

That’s probably the hardest part of it. Getting guys to actually test **** at the track and actually test something.

 

[RustyRatRod]

I've never figured out what the fear is with timing. It's SO EASY to change. Just change it to something different and see what works. It's not like you lose the adjustment and caint put it RIGHT BACK where it was, yet so many guys just seem scared to mess with it. I bet half the guys on this forum could pick up a noticeable power increase if they'd just experiment with the timing curve.

 

[9secRR]

Not on drag car stuff yet. But several circle track cars. They all picked up.

I also have to find someone who is willing to test it at the track. Honestly, most guys don’t want to test. And if they do it’s make a change, make a pass and if it doesn’t pick up a half a second they want to go back to what they had.

That’s probably the hardest part of it. Getting guys to actually test **** at the track and actually test something.

True most guys don’t want to try just in case they slow down. I’m the opposite, if it doesn’t work put it back to the previous setting.

I read the plugs a lot just to see what’s going on. Slowing learning more as my car gets faster.

Would having a curve vs. locked show different on the plug?

 

[TT5.9mag]

Would having a curve vs. locked show different on the plug?

No. The plug is going to show (at wot) what the heat and fuel in the chamber are doing to the plug at the end of the run. You need dyno time or lots of street miles at partial throttle to read a plug for low rpm, low load timing changes.

 

[TT5.9mag]

Why isn't it ideal? As RPM increases, so does cylinder pressure. I think a little retard at the top is generally a good thing. Not to mention, retarding timing helps top end power and it does it automatically. I don't give a CRAP what forum gurus say, those are FACTS.

Come on. You’re smarter than that.

 

[92b]

Well , I remember reading here someone said ALL ignition boxes retard timing at higher RPM. Didn't pay much attention to it, but maybe should have.

I decided to check mine before I fog the motor down for the winter and don't ya know, 35 Degrees locked, at around 4600 RPM it retards 3 or 4 degrees. Not ideal, since my shift light comes on at 6600. My ignition is a FAST box with rev limiter and built in 2 step. Trying to figure out a fix.

Forget telling me to put a curve in my distrib, and locked is no good..... I bought the bushing kit from 4 Seconds Flat, tried 3 or 4 different curves and my car with my engine just wants 35 degrees. Starts better, idles better and is quicker.

I'm wondering when this engine was on the dyno a few years ago, was HIS box retarding my timing also? If so I guess I'm ok, but it's been buggin' me.

Leave it alone or somehow correct it?

Are you using a fast distributor? Also I think you will notice less retard from 4600 to 6600.

 

[9secRR]

No. The plug is going to show (at wot) what the heat and fuel in the chamber are doing to the plug at the end of the run. You need dyno time or lots of street miles at partial throttle to read a plug for low rpm, low load timing changes.

that's what i thought but wanted to ask. no dyno time or street miles for me, drag only.

 

[Newbomb Turk]

If you are using a dist with a mag trigger, you will get some retard as rpm increases from distortion coming from the p/up coil. Only thinking out loud now, but I can see two areas coming from the timing light itself that could produce a retarded reading [ time lag ] The clamp that picks up the high voltage in the leads is a ferrite inductor; if it has a wire coil around it to amplify the signal, then that coil takes time to reach max current value. Also, the Xenon lamp in the timing light. Xenon is a gas; it requires an ionising voltage to ignite it & that is going to take time also.

All timing lights have a slew rate, just like ignition boxes.

You can see the difference on a test bench. If you check several lights on the same engine, the light with the least amount of timing showing has the least amount of slew rate.

In the end, it doesn’t really matter as long as you use the same timing light all the time. While the numbers may be different, the shape of the curve the engine wants will be the same.

 

[Newbomb Turk]

Are you using a fast distributor? Also I think you will notice less retard from 4600 to 6600.

How so?