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05-04-2008, 06:00 AM | #1 |
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Timing Light Question
just curious on how to use a timing light and a vacuum gauge, if possible break it down to retard language lol. id like to dail in the ole pick em up
-G.Lester
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05-04-2008, 06:21 AM | #2 |
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Re: Timing Light Question
you buy them and read the instruction book that is in the box//thats about as basic as it gets
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05-04-2008, 06:27 AM | #3 | |
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Re: Timing Light Question
Quote:
If you need that much direction, it may be better to take it to a shop.
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05-04-2008, 06:31 AM | #4 |
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Re: Timing Light Question
well i have the tools, i can tune one by ear i would just like to learn how to properly use the guage and light.... and i always like things broke down as simply as possbile becoz it cuts down on repeat questions...
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05-04-2008, 06:49 AM | #5 | |
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Re: Timing Light Question
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If you can actually "tune" a motor by ear, you don't need to use either of the tools you asked about. There are a ton of motor builders out there that can't tune a motor by ear, they can get close.... however close & luck doesn't actually "tune a motor. No disrespect, but tuning by ear because you were lucky once and the motor ran ok doesn't count. If you can tune a motor by ear you have probably built a few motors or have been around folks that have, if you can build a motor then connecting a timing light and pointing it at the harmonic balancer should be common sense or fairly easy to figure out. There really isn't anything to "break down" on using a timing ight.
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05-04-2008, 11:35 AM | #6 |
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Re: Timing Light Question
If you have a regular(non-dial back) timing light all you can really do is check idle timing and unless the engine is totally stock the factory spec isnt likely the best setting. You can use it to check total timing (what you really want to set)if you put degree tape on the balancer but youre really better off with a dial back type light.
Use of the timing light is pretty straight forward, hook up the power leads to the battery, clamp the inductive pick-up on the #1 cylinder spark plug wire and point the gun at the timing tab on the timing cover. When the light fires look for the mark on the balancer and see where it is in relation to the timing tab, that will show you how far advanced/retarded the spark timing is under the current conditions. As far as the vacuum gauge goes, all youre really going to want to do is use it to set idle mixture. Basically you set youre idle speed then mess with the idle mixture screws until you get the highest possible vacuum reading then readjust idle speed and repeat the process until you have the highest possible vacuum reading. That will give you close to lean-best idle and will provide easy start up and nice idle/off-idle driveability. |
05-04-2008, 02:59 PM | #7 | |
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Re: Timing Light Question
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Good info but look at what type of engine you may be working on---there are some (not in the GM world), that time off of a different plug other than good old #1. International comes to mind. |
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05-04-2008, 03:38 PM | #8 |
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Re: Timing Light Question
well you hook your vacum light up to your number one plug wire, with the engine running you point it down at the balancer and look for your timming marks if you can see them great if not sucks to be you , I think I'm set at around 12 advanced with no vacum advances since I'm running a blower, call summit and ask them what they think you should start with, and vacum, your looking to get as much at idel as you can I think I got around 20 at idel and it stays solid as a rock grab someone who has done it before and have them teach you how about 2 months ago I would be asking how to do it but you learn it qick after 2 or 3 times. turn the base of the distributor until you go the way you want and lock it down when your done
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05-04-2008, 10:12 PM | #9 |
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Re: Timing Light Question
I think folks are making this too hard Retselgerg, I give you major props for wanting to learn this. It's not hard at all, and it's a great skill to have. "Tuning by ear" will almost always give too much initial advance.
Maybe we can tweak this as a group and make a FAQ. To set base timing - timing without mechanical or vacuum advance - follow the steps below. Note that I agree that you should get the service manual for your truck - you'll need it. And this is only for our 67-72 trucks, as noted there are differences for other years. Finally, if you're looking to set performance timing by adjusting the mechanical and vacuum advance - that's a different topic. Setting Idle Mixture
Setting Base Ignition Timing
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05-04-2008, 10:40 PM | #10 |
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Re: Timing Light Question
The first 2 responses were so darn informative!
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05-05-2008, 02:01 AM | #11 |
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Re: Timing Light Question
Thanks to the guys that responded with info - especially Billla! I have never owned a light or vac gauge (I have always just done it by ear, also, but, I plan on buying a light to tune my BBC when I finally get home to fire it. Thanks!
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05-05-2008, 06:15 AM | #12 |
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Re: Timing Light Question
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05-05-2008, 06:36 AM | #13 | |
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Re: Timing Light Question
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05-05-2008, 06:35 AM | #14 |
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Re: Timing Light Question
But I have a question now. What if your motor isn't stock? running a different cam? How do you get the timing setting then? I have always done it by ear, when this was the case. But I would definately be inclined to listen to everybodies tricks.
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05-05-2008, 06:49 AM | #15 | |
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Re: Timing Light Question
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Not to beat a dead horse, but you CANNOT time an engine by ear, period. It will always end up too far advanced - it may run OK, but it's not returning it's best driveability, fuel economy or power. |
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05-05-2008, 07:36 AM | #16 |
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Re: Timing Light Question
lots of good info, for the record the engine is a stock 260hp crate engine with less then 300 miles on it, and although this may be a pretty straight forward thing for most folks im different. I dont like to do stuff at a mediocore level, i like to master them i figure that if they can make a science out of bottling water then i can make a science out of most anything i attempt. Thanks for the info i now believe i can handle the tuning task.
thanks G.Lester
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"OLE BLUE" Goodwrench 350, 5speed, Tilt, PS, PB, "some guys got into cars for money or girls but i got into cars because of the cars" -Jay Leno Last edited by retselgerg; 05-05-2008 at 07:44 AM. |
05-05-2008, 07:41 AM | #17 |
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Re: Timing Light Question
I'll place $20 on the hood for anyone that can get "close" by ear. I've never tuned one that's been tuned "by ear" that didn't have 16+ degrees of timing at idle, because that's where it sounded "right".
Not trying to be a d*ck (really ), it's just something that's a science - not an art. |
05-07-2008, 05:52 AM | #18 | |
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Re: Timing Light Question
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05-07-2008, 06:00 AM | #19 | |
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Re: Timing Light Question
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05-07-2008, 06:44 AM | #20 | |
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Re: Timing Light Question
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05-07-2008, 07:31 AM | #21 | |
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Re: Timing Light Question
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NOTE: This kind of tuning is not neccessary for stock engines, and is not required. This is more suitable to engines that see frequent high RPM use! Setting base timimg works well for stock engines, but total timing yields the best performance results, and is really a must for high performance engines. It works just like base timing except focusing on getting the 6 - 10 degrees at idle, you tune it by setting the timing when the distributor is at full advance usually 3000 - 3500 RPM. The TDC marks on a lot of stock (especially high mileage) balancers are dead wrong. The foolproof way to insure your mark is correct is to pull the INT and EXH rockers off #1 and screw a piston stop into the #1 hole and go all the way clockwise until it bumps the stop and lightly scribe a line at TDC on the balancer. Do the same counterclockwise and lightly scribe another line. The distance between the these 2 lines will depend on how far the piston stop extends into the cylinder. Its doesn't what the distance is, but you have to measure it with a dail calipers and split the difference, and scribe a line between them. For example, if the lines are .800" apart, set the calipers to .400" and scribe a line between them. This is the TRUE TDC mark. If its in the same location as the stock mark, you're lucky because all too often its not. After you've determined TDC, you can use a timing light that has advance capability, so you can go old school, and put timing tape on the balancer. Again, that old-tech tape is foolproof. An after market racing balancers such as welded hub balancer or a Fluidampr already have these marks. With the advance disconnected and plugged (same as setting initial) pull the engine up in RPM increments of 1000 and you can watch and graph the full advance curve. Pull it up until it is no longer advancing which is usually between 3000-3500 sometimes even 4000. On lower compression engine you can run as much as 40* but most fall in the 36-38* range. Higher compression engines usually range in 32*-34* range. The object is to run as much timing as you can without detonation. You can then adjust the timing curve by changing springs and weights. If the advance curve is coming in too slowly, you add lighter springs and springs if needed until you achieve the desired curve. If total is coming too quickly, just go vise versa and add heavier springs. The weight and spring kits usually come with a couple of graphs showing typical advance curves and a general guideline of what weights and springs to use, but it is what is, just a guideline. You have to check with the light because the pink or red spring doesn't always do what that graph says its gonna do!
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05-08-2008, 03:07 PM | #22 |
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Re: Timing Light Question
I think the challenge I was having was the wording around setting total advance, and then adjusting the timing at idle "if adjustable". Sorry for the confusion I caused; it was just semantics in the answer - if you read back, what you're talking about is exactly what I do...it was just a different way of saying it
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