Help needed with timing marks
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
Likes: 31
From: Nashville, TN
Help needed with timing marks
I recently replaced the distributor in my SBC 350 aligning it in the same location as the original. The car starts well but runs a little rough and I want to double check the timing. I'm familiar with how to use a timing light but by no means expert. The block has a timing tab bolted to it with graduations from 0 - 8 retarded and 0 to 14 advanced. The harmonic damper has a gauge etched into the metal around the outside from 0 to 60. I was expecting to only see a single line or a notch on the harmonic balancer that I would I then align to the appropriate setting on the tab using the timing light (I'm wanting about 10 degrees advanced). I'm not sure now what aligns to what with both the timing tab and harmonic balancer having a range of numbers. Any advice?
Thanks in advance.
Thanks in advance.
Melting Slicks
Joined: Apr 2021
Posts: 2,671
Likes: 2,124
From: Minnesota
Do you have a conventional timing light without adjustment or a dial back style?
If you have a conventional timing light you’ll want to line up the 0 on the harmonic balancer with the 10 on the timing tab to get 10 degrees advanced.
Although for setting up your optimal timing you’ll want 36 degrees total.
I would put a mark on the balancer at 36 degrees, and at 0 on the tab. Rev up the car with the vacuum advance unplugged and capped off until you get your maximum mechanical advance. One the marks are lined up you’ll probably find that your initial timing number will be somewhere in the mid to high teens.
If you don’t have a copy of Lars’s timing papers I would send him an email.
If you have a conventional timing light you’ll want to line up the 0 on the harmonic balancer with the 10 on the timing tab to get 10 degrees advanced.
Although for setting up your optimal timing you’ll want 36 degrees total.
I would put a mark on the balancer at 36 degrees, and at 0 on the tab. Rev up the car with the vacuum advance unplugged and capped off until you get your maximum mechanical advance. One the marks are lined up you’ll probably find that your initial timing number will be somewhere in the mid to high teens.
If you don’t have a copy of Lars’s timing papers I would send him an email.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
Likes: 31
From: Nashville, TN
Do you have a conventional timing light without adjustment or a dial back style?
If you have a conventional timing light you’ll want to line up the 0 on the harmonic balancer with the 10 on the timing tab to get 10 degrees advanced.
Although for setting up your optimal timing you’ll want 36 degrees total.
I would put a mark on the balancer at 36 degrees, and at 0 on the tab. Rev up the car with the vacuum advance unplugged and capped off until you get your maximum mechanical advance. One the marks are lined up you’ll probably find that your initial timing number will be somewhere in the mid to high teens.
If you don’t have a copy of Lars’s timing papers I would send him an email.
If you have a conventional timing light you’ll want to line up the 0 on the harmonic balancer with the 10 on the timing tab to get 10 degrees advanced.
Although for setting up your optimal timing you’ll want 36 degrees total.
I would put a mark on the balancer at 36 degrees, and at 0 on the tab. Rev up the car with the vacuum advance unplugged and capped off until you get your maximum mechanical advance. One the marks are lined up you’ll probably find that your initial timing number will be somewhere in the mid to high teens.
If you don’t have a copy of Lars’s timing papers I would send him an email.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
Likes: 31
From: Nashville, TN
No, upon second read you're saying the other way around. Time to 35 at full adv which will be teens at idle?
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
curious the balancer is lined.
been trying to remember where I saw that before stock,
only car for sure was a ford.
anyhow, unless you suspect the "0"s don't match, pick one set of marks and time away
been trying to remember where I saw that before stock,
only car for sure was a ford.
anyhow, unless you suspect the "0"s don't match, pick one set of marks and time away
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
Likes: 31
From: Nashville, TN
I should have mentioned that its not a stock motor. Its a rebuilt motor with some mild performance work done such as heads, intake, and exhaust.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
When someone mentions total advance at 36*, they mean reving the snot out of it with one hand, timing light in the other.
In others words, about 3,000 RPMs.
Lock down the dizzy.
Your Intial Timing will fall where it may (10 - 16) at idle. Unimportant.
In others words, about 3,000 RPMs.
Lock down the dizzy.
Your Intial Timing will fall where it may (10 - 16) at idle. Unimportant.
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
you can read large amount of adv with a simple basic light.
so doing the "all in" at 3000 rpm check for 36deg, no vac adv hookedup, a breeze.
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Yes I run a aftermarket balancer with timing marks out to 60. It also has lines on it every 90 degrees for valve adjustments.
use only the zero mark on your tab. Use the degreed marks on the balancer. Good idea to put a white or red paint dot right on 36 degrees (If that's what your shooting for) before you start to help you see it clearly as you rev the snot out of it!
use only the zero mark on your tab. Use the degreed marks on the balancer. Good idea to put a white or red paint dot right on 36 degrees (If that's what your shooting for) before you start to help you see it clearly as you rev the snot out of it!
Racer
Joined: Sep 2021
Posts: 418
Likes: 131
From: Upstate South Carolina
I have always shared this as it seems to be the easiest to understand
https://www.onallcylinders.com/2020/...nitial-timing/
https://www.onallcylinders.com/2020/...nitial-timing/
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
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From: Nashville, TN
Thank you everyone for the awesome information. Incredibly helpful! I've decided to set the timing in two phases. Because the initial timing was a bit of a guess when I swapped the distributor I'm going to time it first at idle to around 10 DEG ADV. Once I've done that I will then time to 36 DEG ADV @ 3000 RPM. My logic in doing it twice is that if the current timing is a bit retarded revving to 3K straight off is likely not a good plan. Timing it at idle first means its at least close before I rev the snot out of it.
Thanks everyone.
Thanks everyone.
Race Director
Joined: May 2006
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If you have the stock 1972 distributor in your car using the factory stiff advance springs, revving it to 3k rpm will not show maximum advance. You need a Mr Gasket 928G spring kit and choose the appropriate combination of springs that enable maximum advance at 3k rpm.
Thread Starter
Instructor
Joined: Sep 2019
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From: Nashville, TN
I have the MSD Street Fire HEI which includes optional advance components.
Race Director
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Then you have to check the instructions for that unit to see what has to be done to achieve maximum advance at 3k rpm. It may also tell you how much advance you get from the distributor so you only have to set initial and not rev the engine. For instance if they give you the setting for 24 degrees from the distributor internally set initial timing to 12 BTDC.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
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From: Nashville, TN
Then you have to check the instructions for that unit to see what has to be done to achieve maximum advance at 3k rpm. It may also tell you how much advance you get from the distributor so you only have to set initial and not rev the engine. For instance if they give you the setting for 24 degrees from the distributor internally set initial timing to 12 BTDC.
Thread Starter
Instructor
Joined: Sep 2019
Posts: 238
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From: Nashville, TN
Then you have to check the instructions for that unit to see what has to be done to achieve maximum advance at 3k rpm. It may also tell you how much advance you get from the distributor so you only have to set initial and not rev the engine. For instance if they give you the setting for 24 degrees from the distributor internally set initial timing to 12 BTDC.
Race Director
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They dont mention anything about springs to bring it down to 3k? With 22 degrees you want initial at 14.
Thread Starter
Instructor
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From: Nashville, TN
Yes. They mention three things; 1/ the mechanical advance is pre-tuned to provide 22 degrees @ 4000, 2/ A vacuum advance stop kit can be fitted that allows you to limit the vacuum advance between 0 and 17, and 3/ an optional advance kit that allows adjustment of the centrifugal advance which is what I think you are referring to but it does not go into details on the adjustment ranges possible. What I don't understand yet is how the mechanical and vacuum advances interact together. For example; If I time the car to 36 @ 4000 with the vacuum disconnected does that mean when the car is in operation with the vacuum connected the total advance degrees will be 36 plus whatever the vacuum adds or does one take precedent over the other?
Race Director
Joined: May 2006
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Yes. They mention three things; 1/ the mechanical advance is pre-tuned to provide 22 degrees @ 4000, 2/ A vacuum advance stop kit can be fitted that allows you to limit the vacuum advance between 0 and 17, and 3/ an optional advance kit that allows adjustment of the centrifugal advance which is what I think you are referring to but it does not go into details on the adjustment ranges possible. What I don't understand yet is how the mechanical and vacuum advances interact together. For example; If I time the car to 36 @ 4000 with the vacuum disconnected does that mean when the car is in operation with the vacuum connected the total advance degrees will be 36 plus whatever the vacuum adds or does one take precedent over the other?
Drifting
Joined: Nov 2016
Posts: 1,957
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From: Pittsburgh PA
give that you now know how much advance the MSD has in it, you can set base to 14, plus the 22 in the MSD will give you the 36 yes. you will need the "advance kit" which im assuming is springs, to bring the advance in quicker.
regarding vacuum- yes you are correct with the addition of vacuum you can see total advance up into the high 40s possible 50s. that is perfectly normal for cruising "no load" situations. the minute you step on the gas and vacuum drops you lose that vacuum advance portion.
i find the easiest way for me to step timing is to use a dial back light, i paint 0 on the timing tab and balancer with white paint, set my dial back like to what i want (in your case 14 at idle) then just line up the 2 marks. done
regarding vacuum- yes you are correct with the addition of vacuum you can see total advance up into the high 40s possible 50s. that is perfectly normal for cruising "no load" situations. the minute you step on the gas and vacuum drops you lose that vacuum advance portion.
i find the easiest way for me to step timing is to use a dial back light, i paint 0 on the timing tab and balancer with white paint, set my dial back like to what i want (in your case 14 at idle) then just line up the 2 marks. done