Setting timing on a 77 L48
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,073
Likes: 65
From: Belgium
Setting timing on a 77 L48
Hey everyone
I will (re-)set the timing of my stock1977 L48 with open longtube headers for the first time...
I did some reading, and think I will just have to do the following.
- I have a timing light.
- I have to dial in 36 degrees BTDC on the light, then just set the timing so that the marker on the damper is at "0" on the pointer.... Then I'm OK to go?
Please confirm?
I will (re-)set the timing of my stock1977 L48 with open longtube headers for the first time...
I did some reading, and think I will just have to do the following.
- I have a timing light.
- I have to dial in 36 degrees BTDC on the light, then just set the timing so that the marker on the damper is at "0" on the pointer.... Then I'm OK to go?
Please confirm?
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Yes, with the vacuum hose disconnected from the distributor and plugged. Once set at 36*, reconnect vacuum hose and check timing again. It should read somewhere around 50* at 3600 rpm. Take for a test drive. If you detect any pinging, retard timing by 2* increments until ping is gone.
Last edited by resdoggie; Apr 11, 2019 at 10:00 AM.
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,073
Likes: 65
From: Belgium
Yes, with the vacuum hose disconnected from the distributor and plugged. Once set at 36*, reconnect vacuum hose and check timing again. It should read somewhere around 50* at 3600 rpm. Take for a test drive. If you detect any pinging, retard timing by 2* increments until ping is gone.
I just know it is bad for the engine.
Last edited by Novusuhu; Apr 11, 2019 at 10:04 AM.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
It sounds something like rocks rattling in a can. More pronounced under light throttle going up a hill. Anyway, you'll hear it if your timing is too far advanced.
***The method I described is just a basic timing procedure assuming your engine is in good mechanical condition***
***The method I described is just a basic timing procedure assuming your engine is in good mechanical condition***
Last edited by resdoggie; Apr 11, 2019 at 10:21 AM.
Thread Starter
Burning Brakes
Joined: Sep 2017
Posts: 1,073
Likes: 65
From: Belgium
I read that when your engine is pinging there will be direct damage to the engine?
Last edited by Novusuhu; Apr 11, 2019 at 10:23 AM.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
34°is better with a small block. The extra 2 degrees does not produce any more power. And this timing is at 3000 rpm with vacuum advance disconnected. FIRST check idle timing with vacuum unhooked and again when hooked up. Unhooked you will see mark on tab with light set to 0. Probly hafta dial light back for idle with vacuum. NOW rev to 3000 and dial light til timing mark is at 0. Check dial for timing. Now you know what you had. And you know how much mechanical and vacuum advance distributor has. Now set it to 34 degrees at 3000. Now check new idle timing. Now hook up vac and re-check idle and 3000.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
So you can only see if your timing is right, when risking a pinging engine? Back in the day, yes, so some believed. Some guys advanced the timing to the point where it began to ping and then backed it off a degree or two to eliminate the ping.
I read that when your engine is pinging there will be direct damage to the engine? Not necessarily if its not severe but if not corrected, over time it will do it's damage.
I read that when your engine is pinging there will be direct damage to the engine? Not necessarily if its not severe but if not corrected, over time it will do it's damage.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
From your first question, you stated "open longtube headers". If you have open headers, odds are you won't be able to hear if it's pinging or not. From that, I'd suggest being conservative with timing.
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Brett Foote
Tech Contributor
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From: At my Bar drinking and wrenching in Lafayette Colorado
I don't see anyone stating this, but the 36-degree timing spec is at maximum, "pegged-out" centrifugal advance, which can be at any rpm between 2500 and 5000 if the distributor has stock springs in it... You can't just set the timing at 36 at any rpm, or at 3000, and assume that the timing is pegged out.Make sure the centrifugal is fully pegged out, and then set the timing at 36. Once done, tailor the springs to achieve this spec at 2800 - 3000 rpm.
Lars
Lars
Last edited by lars; Apr 14, 2019 at 10:34 PM.