These cars run better when you default to pre-emissions settings.
Setting Timing Correctly?
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 15
Likes: 0
From: Alpharetta GA
Setting Timing Correctly?
Hi,
I have a 1972 LT-1 and believe my timing is off. Before adjusting the distributor, I wanted to confirm my approach.
The shop manual for my year and engine indicates 4 degrees is the correct setting. A reply to another thread had theirs set at 16 for this same year/engine. Here are my readings using the big notch in the center of the timing tape as center. (Yes, I disconnected the vacuum advance.)
@900 warm idle - 14
@2500 - 41
When I set the timing light to 4 at warm idle, the line on the harmonic dial is centered at the second small notch north of the big notch.
Based on what I'm reading, I should adjust the distributor until the line is centered on the big notch at warm idle with the timing light set to 4. First, is 4 what you would recommend? Second, is that the right approach for determining current setting before making the adjustment?
Thanks!
I have a 1972 LT-1 and believe my timing is off. Before adjusting the distributor, I wanted to confirm my approach.
The shop manual for my year and engine indicates 4 degrees is the correct setting. A reply to another thread had theirs set at 16 for this same year/engine. Here are my readings using the big notch in the center of the timing tape as center. (Yes, I disconnected the vacuum advance.)
@900 warm idle - 14
@2500 - 41
When I set the timing light to 4 at warm idle, the line on the harmonic dial is centered at the second small notch north of the big notch.
Based on what I'm reading, I should adjust the distributor until the line is centered on the big notch at warm idle with the timing light set to 4. First, is 4 what you would recommend? Second, is that the right approach for determining current setting before making the adjustment?
Thanks!
Tech Contributor
Joined: Jun 2004
Posts: 20,847
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
The factory timing setup is made for emissions and warranty/durability. Other timing numbers are suggested for performance and economy. Which are you interested in?
Pro
Joined: Dec 2014
Posts: 699
Likes: 46
From: Charlotte NC
There is no exact correct static advance timing that is best for every engine IMHO. I like as much timing as the car can stand without pinging, or other problems. You can easily modify the advance curve and limit travel to set total advance where you want it. A high static advance gives you a stronger idle and better vacuum.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Make sure your mechanical advance is free- not stuck/sticking or binding. Disconnect the vacuum advance, set your timing light to 0* and see where the timing mark on the balancer is. TDC (0*) is the biggest notch with each notch or point being 2* IIRC.
Personally, I'd run the timing at 8-10*, but limit the total (initial and mechanical) to 36* at 3000 PPM, but the quality of gas you're using may play into that also. You should email Lars and get a copy of his timing paper-
Personally, I'd run the timing at 8-10*, but limit the total (initial and mechanical) to 36* at 3000 PPM, but the quality of gas you're using may play into that also. You should email Lars and get a copy of his timing paper-
Le Mans Master
Joined: Aug 2006
Posts: 7,417
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Thread Starter
Heel & Toe
Joined: Dec 2017
Posts: 15
Likes: 0
From: Alpharetta GA
That's a great point I should have thought about first. My car already had the smog pump and emissions device between the carb and vacuum intake removed. My priorities are reliability, durability, and lastly performance. This is a fun car to cruise around in for me.
Le Mans Master
Joined: Dec 2006
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