How to Use a Digital Timing Light With Advance
 Understanding how to use Advance Timing Light #740403 07/04/10 05:24 PM 07/04/10 05:24 PM | |
 OP member Joined: Sep 2009 Posts: 153 Georgia | Ok I got two batteries charged so we can get this 400 started and everything adjusted. It started up right away. I let it run a few seconds and zapped the throttle to let off the fast idle. But I think timing is off. It's idling way too high, like maybe 1200RPM in Park. I got scared running that high on a new motor eventhough the cam break is done. I tried to turn out the idle screw to adjust it but it didn't even really change. So I think the timing is off some. I have this Advance timing light that I'm not really familiar with. I'm following the instructions with the timing light. It has a knob on it you turn for Advance it goes from 0-60. It tells me for setting initial timing to "Turn knob to desired degree advance setting." I don't really know what that means. I can sit there and set the timing to exactly what the specs are but that's about it. And that's what I was going to do being it's all built back stock. The spec is 7.5 +/- 2.5 degrees, so basically 10 Before Top Center. So I was going to put it at 10 BTC and see how it ran. But what am I suppose to do with this Advance knob. After selecting the desired Advance it says to press and hold down the button, view timing marks. Loosen dist. and turn until movinv mark is at 0. Then it says to tighten the bolt back up. Why would I want to put it back at 0? Or do I just turn the knob to 10 and follow the instructions and turn the dist. until it's back to 0. Please help. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740404 07/04/10 05:44 PM 07/04/10 05:44 PM | |
| Joined: Nov 2003 Posts: 35,939 Lincoln Nebraska RapidRobert Circle Track | |
| Circle Track Joined: Nov 2003 Posts: 35,939 Lincoln Nebraska | Quote: (A) turn the knob to 10. then turn dist until the timing marks on the dampener, the slit is on zero (TDC). tighten the dist and recheck your timing that it didn't move during the tightening. (B) or leave the knob at zero adv and turn the dist until the balancer slit is at 10 BTDC. (A or (B) will time it the exact same place and since 10 BTDC is located on the tab you can use (A) or (b) whereas the tab doesn't go up to 35 total (SB)/36-38 (BB) so you would need to use (B)to find your total or any amt of advance that's more than what the tab shows live every 24 hour block of time like it's your last day on earth |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740405 07/04/10 05:48 PM 07/04/10 05:48 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | On most stock crank dampners the marks on it only show +10, +5, 0, -5, -10. |
| Re: Understanding how to use Advance Timing Light [Re: 66Dodge] #740406 07/04/10 06:03 PM 07/04/10 06:03 PM | |
| Joined: Jan 2003 Posts: 25,200 Upper Midwest MoparforLife Too Many Posts | |
| Too Many Posts Joined: Jan 2003 Posts: 25,200 Upper Midwest | Quote: And you can't do this unless you have recalibrated distributor that is fully advanced before said 2800 RPM's |
| Re: Understanding how to use Advance Timing Light [Re: 66Dodge] #740407 07/04/10 06:07 PM 07/04/10 06:07 PM | |
| Joined: Sep 2009 Posts: 153 Georgia wh23g3g OP member | |
| OP member Joined: Sep 2009 Posts: 153 Georgia | Ok I read the instructions again with the timing light and I did the "Measuring Initial Timing" Procedure. I held down the button, Viewed the Marks, and turned it until the moving mark was aligned with the 0 on the tab. Then I shut the car off and looked at where I had turned the knob to and it was 35-36. So what does that mean? The next step in the instructions with the timing light are a little confusing. The 1st instruction is to "Turn the Advance knob to desired degrees advance setting." So do I leave the knob still at 35-36 and turn the distributor until the white mark I painted on the damper is aligned with 0? Or do I turn the knob back to 0 and aligned the paint mark with 10? I'm assuming this "moving mark" they're telling me to observe in the "Measuring Initial Timing" was the one the strobe light was making. It's confusing because in the "Setting Initial Timing" instruction you're doing the same thing except first youre suppose to turn the knob to a certain number. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740408 07/04/10 06:27 PM 07/04/10 06:27 PM | |
| Joined: Sep 2009 Posts: 153 Georgia wh23g3g OP member | |
| OP member Joined: Sep 2009 Posts: 153 Georgia | Ok I went out and followed what you said RapidRobert and I got it perfectly aligned with 10BTC. The motor settled down and idled lower. It's still idling a little higher than it should at about 1000-1100. You can tell it's still idling a little on the high side. So I know I need to readjust. I have the air cleaner off because there's no way to get to the curb idle screw on the Thermoquad with the air cleaner on. So I hooked back up the vacuum advance. I have the air cleaner hose port on the back of carb plugged up while the air cleaner is off. I sat there and turned out the curb idle screw but it never changed the idle. One thing I'm noticing is the carb has a lot of smoke coming out of it after you shut it off. It probably needs the mixture adjusted. I really don't know how to do that. One veteran mechanic told me to not mess with it and let it run a little lean or rich I can't remember what he said, but he says if you changed it right away it might melt a piston. I can feel the fumes, it burns my eyes a little. And you can smell it on your clothes while out there adjusting. But I checked the timing again after I tightened the screw and it's still dead on 10. So what do I need to do now. Oh yeah I forgot to add that when I finally got the timing right the oil pressure dropped from 75PSI to about 30-35PSI. I'm assuming that's because it was running at 1000 vs 1200 RPM. It just shocked for a second. But that's correct isn't it? I've got HP pump there and when it was running before the timing was adjusted it was 75PSI. So is that normal? Last edited by wh23g3g; 07/04/10 06:30 PM. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740409 07/04/10 06:28 PM 07/04/10 06:28 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | Initial timing is set at idle. Your idle speed should be about 800-900 rpms. Not 1200 rpms. You really can't set anything with your timing light until you get that idle speed down to normal. For plain stock grocery getters the initial timing is typically 10deg (advanced). For performance cars it's typically 15-20deg. You seemed to follow the procedure correctly, but how the heck you came up with 36deg (initial) is beyond me. Provided your initial timing is say 10deg. the next step the instructions was telling you was to set total timing. Basically, what the advance knob does is it allows you to set timing to what whatever you desire by simply turning the knob to the desired number AND allows you the convenince of using the 0 mark on the dampner as your target/reference/set point. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740410 07/04/10 06:35 PM 07/04/10 06:35 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | Going from 1200 rpms to 1000rpms is not a lot of change. It's like your carb butterfly plates are still too open and not closing all the way down. That's probably why your smelling so much gas fumes. Also, too lean a condition will melt a piston. If you can smell the gas then it's too rich. |
| Re: Understanding how to use Advance Timing Light [Re: 66Dodge] #740411 07/04/10 06:57 PM 07/04/10 06:57 PM | |
| Joined: Sep 2009 Posts: 153 Georgia wh23g3g OP member | |
| OP member Joined: Sep 2009 Posts: 153 Georgia | Yeah I'm definitely not an expert but I'm good at following instructions to the T. I'm amazed that I actually put this car back together and rebuilt this engine and that it actually runs. It is my first time ever. That's what I did. I never have been able to adjust a carburetor. It seems like no matter what carburetor I'm working on I can never get it to idle right or adjust right. I followed the timing light instructions so I was making sure I used the timing light right. It was actually more like 30-32 degrees that I turned the knob to get the moving mark to align with 0 when measuring initial timing. So I just turned it back the knob to 0 and aligned the white mark I painted on the damper with the 10 BTC on the cover. I also followed the timing procedure in the 73 Chrysler Chassis Manual. It said once you have the timing to readjust the idle. But like I said I couldn't get the idle to change at all. I turned a few turns but I didn't know how far out you have to turn the curb idle screw for it to really drop so I just quit messing with it for now. The problem is even if I could find someone to help around here I don't know of anyone who can adjust carburetors anymore. I like to adjust to what is specified and be done. That's why I use a hand held tach. It's running at 1000-1050 idling now. According to the emission decal it should be at 775 for a new engine or 850 for a used engine. So what order do I need to redo all this again. Do I need to do mixture, idle, and timing again? Do you'll know of a foolproof way of adjusting mixture to factory settings? |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740412 07/04/10 07:15 PM 07/04/10 07:15 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | Leave your inital timing alone for now. 10btdc is a good start. What carb do you have ? I hope your not confusing the curb idle screw with the idle mixture screws. |
| Re: Understanding how to use Advance Timing Light [Re: 66Dodge] #740413 07/04/10 07:25 PM 07/04/10 07:25 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | If your carb is an Edelbrock or Carter there should be two screws at the front center near the base. Those are the mixture screws. IICR turn both screw all the way in and back off 1.5 to 2 turns for intial setting. But hold off because you've got to get the idle speed down. If you completely backed off the curb idle screw and the engine is still idling at 1000rpms then something is wrong at the throttle linkage. Something is still stuck open and that could be due to a too short throttle cable. Meaning, if the gas pedal is at the fully up position and the engine is still idling fast because the throttle cable is still being pulled back for some reason. |
| Re: Understanding how to use Advance Timing Light [Re: 66Dodge] #740414 07/04/10 08:31 PM 07/04/10 08:31 PM | |
| Joined: Mar 2005 Posts: 862 Iowa State fan super stock | |
| super stock Joined: Mar 2005 Posts: 862 Iowa State fan | dont forget the ever present idle speeding up vacuum leak.. 1973 Charger, former SE, former auto I'm not trying to be difficult, it comes naturally.... |
| Re: Understanding how to use Advance Timing Light [Re: kilroy] #740415 07/05/10 12:03 PM 07/05/10 12:03 PM | |
| Joined: Sep 2009 Posts: 153 Georgia wh23g3g OP member | |
| OP member Joined: Sep 2009 Posts: 153 Georgia | It is the stock replacement carb, the Carter Thermoquad. It is definitely the curb idle screw I am turning out. I turned it out just a little bit, but I thought the idle should drop right away some. So I may not have turned it out far enough. I did change the throttle cable. I got one from Pioneer. I compared it to the original cable and it was the same length, the only difference being the grommet was larger on the original. I don't think anything is sticking I had someone watch the linkage and everything's moving freely when I press in the gas. I was talking to a friend last night and he told me something that could make a difference but I don't know. He said because I have the air cleaner off it's sucking in more air so it might idle a little higher. I had to remove the air cleaner because it's impossible to adjust the curb idle with it on. So when I took it off I did plug the vacuum port on the carb where the air cleaner vacuum hose went to. I don't really know anyone that could properly adjust the mixture screws. But I say a exhaust gas analyzer for sale on EBAY for $230 w/ digital readout. Would that be helpful if I had it? |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740416 07/05/10 02:15 PM 07/05/10 02:15 PM | |
| Joined: Jan 2003 Posts: 667 CA 66Dodge super gas | |
| super gas Joined: Jan 2003 Posts: 667 CA | Back off the idle screw some more until you get 850-900rpms. The idle increased slightly because the carb was running rich and the added air flow to the carb balanced things out. IIRC, the tube coming from the air cleaner typically goes to the breather on the valve cover. The tube coming from the carb goes to the PCV valve on the other valve cover. The analyzer is nice to have but expensive. Just buying the box is not all that's to it. You have to install an oxygen sensor onto the exhaust pipe. This is done by drilling a hole into a header pipe or exhaust pipe after the cast iron manifold. Weld on a "bung" which is the threaded adapter port. Screw on the oxygen sensor and hook up the wires to the box. A simpler way to way to adjust air/fuel mixture is to read the sparkplug. Start with a baseline adjustment by turning the carb's mixture screws all the way in and then back them out 1.5 to 2 turns. Then go for test drive. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740417 07/05/10 07:52 PM 07/05/10 07:52 PM | |
| Joined: Feb 2009 Posts: 1,274 Ontario.Canada can.al pro stock | |
| pro stock Joined: Feb 2009 Posts: 1,274 Ontario.Canada | ...are you trying to adjust the idle with the idle mixture screws? |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740418 07/05/10 08:55 PM 07/05/10 08:55 PM | |
| Joined: Apr 2010 Posts: 1,216 Under My Car pro stock | |
| pro stock Joined: Apr 2010 Posts: 1,216 Under My Car | Quote: Turn that curb idle screw out until you get it where you need it. When you adjust the air/fuel screws "lightly" seat them and back them out 1 1/2 to 2 turns like the previous poster said. I run a TQ on my engine and it can be a tricky gadget for sure. IF your idle doesn't drop when you back the idle down check for vacuum leaks. What intake are you running, spreadbore I hope. Forget the analyzer, if you want to spend some money I would get a vacuum gauge instead. Adjusting the screws is not that big of a deal, you can do it. As far as idling faster with the air cleaner off, mine doesn't. As far as your linkage are you sure it's letting the throttle come to full rest, if you have it too tight that could keep you in the throttle circuit and not allow the idle circuit to come into play. If you continue to wonder simply unhook the throttle cable and start the engine and see if that makes a difference. |
| Re: Understanding how to use Advance Timing Light [Re: JDMopar] #740420 07/05/10 09:31 PM 07/05/10 09:31 PM | |
| Joined: Oct 2005 Posts: 797 arizona, usa lokalik super stock | |
| super stock Joined: Oct 2005 Posts: 797 arizona, usa | |
disconnect the linkage this will let the plates come all the way closed. then use your idle screw, reconnect the linkage. if the idle picks up, there is your problem. timing will change your idle but your idle will not change your timing.| Re: Understanding how to use Advance Timing Light [Re: lokalik] #740421 07/06/10 09:32 PM 07/06/10 09:32 PM | |
| Joined: Sep 2009 Posts: 153 Georgia wh23g3g OP member | |
| OP member Joined: Sep 2009 Posts: 153 Georgia | I didn't mess with it tonight since I want to do it when I have a lot of time. So I'll try and readjust this weekend. I did look at the linkage tonight and it's possible it maybe too tight. I swapped the original cable with a Pioneer cable, which was all the same except the firewall grommet doesn't fit as snug. So I may have taken too much slack out of the new cable, it's pretty tight. With the car just sitting and the engine off and cold should the curb idle screw be touching? So I'll disconnect it this weekend and see what happens unless I get it straightened out. I haven't messed with the mixture screws at all yet. |
| Re: Understanding how to use Advance Timing Light [Re: wh23g3g] #740422 07/06/10 10:01 PM 07/06/10 10:01 PM | |
| Joined: Jan 2007 Posts: 7,664 IN ahy master | |
| master Joined: Jan 2007 Posts: 7,664 IN | FWIW I found I had to adjust my throttle cable "hot". Enough slack cold wasn't enough hot. Now that I know that, I just leave a little extra. |
How to Use a Digital Timing Light With Advance
Source: https://board.moparts.org/ubbthreads/ubbthreads.php/topics/740403/understanding-how-to-use-advance-timing-light.html