Author Topic: Ignition timing  (Read 2752 times)

Offline john h

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Ignition timing
« on: February 13, 2020 - 06:21:19 PM »
Hi All,
I have a Crate Magnum 360. It's the 300 HP model. I am using Fitech throttle body and it's also controlling my timing. I thought it was running great and I had good cold starts and good throttle response. no pining or run on. The base timing is set at 12* and the handheld agrees with the timing light at Idol and at 1500 RPM. I have an adjustable phasing rotor. The timing curve is whatever their base tune was. I can get the numbers if it becomes an question later, but my current issue is with starting. When the engine would be run to operating temp around 190-200, sometimes I would get kickback when I tried to re-start it. it was not super often but something that would happen only when warm. over the winter here in Wisconsin, I changed out my headers to some Ceramic coated ones and put in a High torque mini starter. After the starter change I would get kickback and very ugly engine buck on every start even if it was a cold start. I read about timing being too advanced will cause this. I marked my #1 post on the cap with the dist body. I rolled the engine around to TDC on #1 (compression stroke confirmed) the mark on the balancer was exactly at 0 timing mark. I rolled it backward to 12* before. I pulled the cap off and the rotor was pointing past #1 on the way to #8 so it was looking like it was retarded not advanced. I pulled the rotor and made sure the reluctor was centered on the magnet, it was. I put my rotor back on and re-phased rotor to lineup with the #1 post exactly. I never adjusted the dist timing at that point. I started the car cold and it fired right up and no kickback etc. when I warmed up I checked the timing and it matched the light with the handheld computer for Fitech. I checked the warm starts multiple times after and starts up and no kickback. why would it run nicely before if I was technically firing on time but the rotor was way past the post? is the starter rotating the engine so fast now with the high torque that it was trying to fire #8 rather than #1 causing my kickback and bucking with the new stater? would I have just had really weak spark when I was turning higher RPM if the rotor was already past the plug post moving to the next cylinder?  How could it have ran so nicely with such weak spark? Please hit me with your opinions.

thanks John
John
73 Cuda
360 Crate motor
FiTech Fuel injection
727 Trans (wishing it had Over Drive)




Offline 70chall440

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Re: Ignition timing
« Reply #1 on: February 13, 2020 - 09:02:26 PM »
I cannot say why it ran started good and then didn't but I do not think the hi torque starter has anything to do with it. If I were to guess, I would say that you were on the edge of being too advanced and after you checked everything you got it set in a better zone. As you know, there is a bit of subjectiveness to timing. You have stumbled upon the magic that is working on cars.. I have seen more than once something work that shouldn't and the other way around.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline john h

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Re: Ignition timing
« Reply #2 on: February 13, 2020 - 09:46:57 PM »
If I did not have a locked out dist with a phasable rotor, I would not have been able to turn the rotor back to the #1 post.  I still cant figure out why it's pointing past the #1 post heading to the #8 Post, rather than pointing at it when the piston is at TDC.  can the drive gear inside slip or lift and and re-seat in a different position?  I have never removed a drive gear.  I don't have a clue how they work. could I have jumped a tooth on the timing chain?
John
73 Cuda
360 Crate motor
FiTech Fuel injection
727 Trans (wishing it had Over Drive)

Offline 70chall440

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Re: Ignition timing
« Reply #3 on: February 13, 2020 - 11:30:55 PM »
Yes, the distributor drive can be moved. While it is possible that the timing chain jumped a tooth, I don't think this is what you are looking at here; your timing chain would have to be pretty sloppy for this to happen.

Just so you know (if you didnt), you have a distributor drive under the distributor that connects to the cam via a helical gear. The bottom part of this drive is a shaft that runs down to the oil pump so that as the cam turns, it turns the oil pump below and the distributor above. The gear can be adjusted or moved because as you may know, the bottom of the distributor has a flat tip that goes into the slot into the gear. The gear is moved so that when the distributor in in place and point at #1, the vacuum advance isn't point at/hitting the firewall or intake.

If your timing chain jumped a tooth, you would have metal in the oil and usually they don't just jump one tooth, usually when one goes more follow as the chain becomes even looser.

In my experience there can be a fine line in timing settings especially in a performance engine. So based on what you are saying, when you have the timing mark lined up with zero on the timing tab the rotor in the distributor is not pointing directly at #1? Or are you are saying that it is not pointed at #1 but is between #1 and #8 when the distributor is at 12* advance?
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)

Offline john h

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Re: Ignition timing
« Reply #4 on: February 14, 2020 - 08:19:29 AM »
Yes, the distributor drive can be moved. While it is possible that the timing chain jumped a tooth, I don't think this is what you are looking at here; your timing chain would have to be pretty sloppy for this to happen.

Just so you know (if you didnt), you have a distributor drive under the distributor that connects to the cam via a helical gear. The bottom part of this drive is a shaft that runs down to the oil pump so that as the cam turns, it turns the oil pump below and the distributor above. The gear can be adjusted or moved because as you may know, the bottom of the distributor has a flat tip that goes into the slot into the gear. The gear is moved so that when the distributor in in place and point at #1, the vacuum advance isn't point at/hitting the firewall or intake.

If your timing chain jumped a tooth, you would have metal in the oil and usually they don't just jump one tooth, usually when one goes more follow as the chain becomes even looser.

In my experience there can be a fine line in timing settings especially in a performance engine. So based on what you are saying, when you have the timing mark lined up with zero on the timing tab the rotor in the distributor is not pointing directly at #1? Or are you are saying that it is not pointed at #1 but is between #1 and #8 when the distributor is at 12* advance?

Yes in both cases.  at 0 the rotor is not lined up with #1 and for sure at 12* BTDC, it's actually past #1 on the way to #8. 
John
73 Cuda
360 Crate motor
FiTech Fuel injection
727 Trans (wishing it had Over Drive)

Offline 70chall440

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Re: Ignition timing
« Reply #5 on: February 14, 2020 - 12:12:19 PM »
Alright then, so what we have is a difference in physical markings and timing readings. What I mean is that when you set the engine at 0 on the compression stroke you can then rotate the distributor housing to alight the rotor with the #1 terminal in the cap. All things being perfect, that is then straight up 0 or TDC.
Current Mopar
70 Challenger RT 440-6 EFI, 73 Cuda 416-6 EFI
05 Hemi Durango, 01 Ram 4x4, 14 Ram 2500 4X4, 10 PCP Challenger 6 spd RT, 01 Viper GTS ACR, 52 B3B w/330 Desoto Hemi, 70 Hemi RR (under const)
Past Mopars
9 x Challengers. AAR Cuda, 4 RR, 2 GTX, 4 Chargers, etc... (too many to list)