URGENT - Timing Setting
Thread Starter
Instructor
Joined: Feb 2011
Posts: 116
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From: Griffith Indiana
URGENT - Timing Setting
Need to know the factory timing setting for a 1980 L48 350 motor please. Am adjusting timing tonight and need to know so that I can set it and work from there. From reading different threads, they go from 6 degrees to 12 degrees BTDC. What is factory setting?
Thanks,
TTERZ
Thanks,
TTERZ
CF JASOC Member
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From: Downtown Annapolis, MD. The Future is where we all have to live. Let's not screw it up.
St. Jude Donor '08-'09-'10-'11
Whatever you do, don't use the SEARCH function.
3rd post down.
http://forums.corvetteforum.com/c3-t...tion-help.html
3rd post down.
http://forums.corvetteforum.com/c3-t...tion-help.html
Thread Starter
Instructor
Joined: Feb 2011
Posts: 116
Likes: 0
From: Griffith Indiana
Harmonic Balance Issue?
Tonight tried to factory time my 1980 V8 Corvette. Was unsuccessful in all attempts. I could never get the harmonic balancer to leave the twleve o'clock position and when I did get it to leave this position, it bounced all over the place was absolutely NO CONSISTENCY. Also attempted to re-position sparkplugs on the cap by one position clockwise as well as one position counter clockwise with absolutely no difference or success....I worked with a fellow mechanic on this process, we even took the driver side valve cover off and visually insured that the number #1 piston was at TDC and we removed the distributor on multiple occasions in an attempt to position the distributor correctly and had distributor in proper position, yet could not get the timing set properly. Also, vacuum advance was removed properly while attempting.
I COULD NEVER GET THE TIMING EVEN CLOSE TO TOUCHING THE TIMING TAB ON THE BLOCK.
However, harmonic balancer was consistently staying at twelve o'clock position, which makes me scratch my head on whether or not harmonic balancer and rubber are defective?
What are we missing??? Worked on this for a few hours with absolutely no success.....Please help!!
TTERZ
I COULD NEVER GET THE TIMING EVEN CLOSE TO TOUCHING THE TIMING TAB ON THE BLOCK.
However, harmonic balancer was consistently staying at twelve o'clock position, which makes me scratch my head on whether or not harmonic balancer and rubber are defective?
What are we missing??? Worked on this for a few hours with absolutely no success.....Please help!!
TTERZ
Racer
Joined: Feb 2012
Posts: 333
Likes: 2
From: Aurora Colorado
Wasn't being a smartass, I asked for confermation that a real mechanic could not set your timing. I did try to help. You Asked what factory timing was and I stated 12 degrees and suggested you read Lars papers, have you?
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Greatsteaks and xCCTer!!! How dare you question the great and powerful tterz!!!!! Tterz is asking the questions here, not you!!!!! You should feel lucky just to be able to bask in the reflected greatness of the wonderfull tterz, even if he doesn't seem to be able to set the timing on a small block chevy, which is something that my 16 year old nephew can do.
Tterz, relax, ok? We are here to help, but that sort of attitude is just going to push people away. My advice is to start at the beginning, make sure the firing order is correct, make sure number 1 cylinder is at TDC on the compression stroke, and if I remember correctly, stock timing on a 1980 L48 is 6 degrees, although I don't see how knowing this will help, since you don't seem to be able to get the timing to settle down and stay put. Maybe pop the distributor cap off and make sure centrifugal advance is operating properly.
Keep the shiny side up!
Scott
Tterz, relax, ok? We are here to help, but that sort of attitude is just going to push people away. My advice is to start at the beginning, make sure the firing order is correct, make sure number 1 cylinder is at TDC on the compression stroke, and if I remember correctly, stock timing on a 1980 L48 is 6 degrees, although I don't see how knowing this will help, since you don't seem to be able to get the timing to settle down and stay put. Maybe pop the distributor cap off and make sure centrifugal advance is operating properly.
Keep the shiny side up!
Scott
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Thread Starter
Instructor
Joined: Feb 2011
Posts: 116
Likes: 0
From: Griffith Indiana
I have read through Lars papers but they do not address the issues that I am having. Also, factory timing for a 1980 corvette is 6 degrees at 500 RPM....still have not figured out my earlier issues and just do not know where to turn, hence my help for assistance.
TTERZ
TTERZ
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Here is a method I use sometimes
Instead of a balloon (balloon just makes it an easy 1 man task), you can use a wadded up piece of paper towel and a friend. The wad should be blow out approaching #1 compression.
You can use a pencil in #1 plug hole and a friend with a wrench on the balancer to rock the piston up and down to TDC to check that the balancer and mark are still accurate.
Instead of a balloon (balloon just makes it an easy 1 man task), you can use a wadded up piece of paper towel and a friend. The wad should be blow out approaching #1 compression.
You can use a pencil in #1 plug hole and a friend with a wrench on the balancer to rock the piston up and down to TDC to check that the balancer and mark are still accurate.
Try this way.
Looking at the front of the engine from the front of the car the balancer turns clockwise. The distributer turns clockwise looking down at it.
Almost foolproof method:
Get an old sparkplug that fits the engine.
Knock the guts out of it with a punch and hammer.
Stretch a balloon over the sparkplug leaving the threads exposed. (Balloons from Dollar Store)
Hand tighten the balloon/sparkplug into the #1 hole.
Disconnect power to distributor or make sure ignition is off.
Slowly turn over engine in clockwise direction with a socket and ratchet on the harmonic balancer center bolt.
Balloon will fill with air when approaching #1 firing position. It won't stay full so you have to watch it closely.
The mark on the balancer will be at approx 6 o'clock, so forget about the ballon and continue turning the engine over.
Continue to turn engine until the mark on balancer reaches the 10° BTDC mark.
This is close to the initial timed firing position.
Install dist with the rotor pointing approximatedly at the #2 terminal on the cap. (Just before #1 on cap)
Push down slowly and you will feel the gears mesh and the rotor will move toward the #1 position.
If it is going to go past #1, then slowly pull up on the distributer until you feel the gears "unmesh". then turn the rotor more towards the #2 direction with slight pressure down until you feel you have moved over 1 more tooth.
Then push down as far as it will go again to see if it is close to lining up with #1 terminal.
If the distributer housing base where you clamp it tight has a gap between it and the intake manifold, then the oil shaft has not lined up.
If this is the case, then the rotor should be between the #1 and #2 terminals on the cap.
Then just push down lightly on the distributer housing (watch out for spinning rotor) while someone cranks the starter over, and it will drop in place and the timing will be correct to fire up.
It may sound a little confusing, but try it and it's pretty simple and is is the easiest way I have found.
To check it, do the balloon thing again with the distributor now being fully seated on the intake. Turn the distributer housing until the rotor leading edge meets the #1 cap terminal. If the housing is oriented properly as in the first pic then you will have ample room for the vacumn advance can to turn the distributer for timing. Now clamp the distributor fairly tight and use you timing lite to time engine to your specs.
Use one of the papers in a sticky at top.
Looking at the front of the engine from the front of the car the balancer turns clockwise. The distributer turns clockwise looking down at it.
Almost foolproof method:
Get an old sparkplug that fits the engine.
Knock the guts out of it with a punch and hammer.
Stretch a balloon over the sparkplug leaving the threads exposed. (Balloons from Dollar Store)
Hand tighten the balloon/sparkplug into the #1 hole.
Disconnect power to distributor or make sure ignition is off.
Slowly turn over engine in clockwise direction with a socket and ratchet on the harmonic balancer center bolt.
Balloon will fill with air when approaching #1 firing position. It won't stay full so you have to watch it closely.
The mark on the balancer will be at approx 6 o'clock, so forget about the ballon and continue turning the engine over.
Continue to turn engine until the mark on balancer reaches the 10° BTDC mark.
This is close to the initial timed firing position.
Install dist with the rotor pointing approximatedly at the #2 terminal on the cap. (Just before #1 on cap)
Push down slowly and you will feel the gears mesh and the rotor will move toward the #1 position.
If it is going to go past #1, then slowly pull up on the distributer until you feel the gears "unmesh". then turn the rotor more towards the #2 direction with slight pressure down until you feel you have moved over 1 more tooth.
Then push down as far as it will go again to see if it is close to lining up with #1 terminal.
If the distributer housing base where you clamp it tight has a gap between it and the intake manifold, then the oil shaft has not lined up.
If this is the case, then the rotor should be between the #1 and #2 terminals on the cap.
Then just push down lightly on the distributer housing (watch out for spinning rotor) while someone cranks the starter over, and it will drop in place and the timing will be correct to fire up.
It may sound a little confusing, but try it and it's pretty simple and is is the easiest way I have found.
To check it, do the balloon thing again with the distributor now being fully seated on the intake. Turn the distributer housing until the rotor leading edge meets the #1 cap terminal. If the housing is oriented properly as in the first pic then you will have ample room for the vacumn advance can to turn the distributer for timing. Now clamp the distributor fairly tight and use you timing lite to time engine to your specs.
Use one of the papers in a sticky at top.
Burning Brakes
Joined: Aug 2006
Posts: 1,058
Likes: 27
From: Eastern North Carolina
The OP is stating that the timing mark is not moving when he tries to adjust it. The only thing I can think of (and its hurts to think) is that some advance is coming from somewhere. If you turn the dizzy the timing mark should move unless the vacuum advance is still connected or its a 80 L-48 from California which used the CCC system like all 81's do and the computer is controlling the advance. Since the Op has stated that he'll get advice somewhere else I won't ask if the timing mark moves when he revs the engine. Good Luck
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Well, the OP claims the vacuum advance was "properly removed". So the car must have a vacuum advance canister on the distributor.
Keep the shiny side up!
Scott
Keep the shiny side up!
Scott
Thread Starter
Instructor
Joined: Feb 2011
Posts: 116
Likes: 0
From: Griffith Indiana
A few days have passed now and I am "humbly" re-posting my initial request with different manorisms....I apologize for earlier statements that were made, but at that time frustration had set in and my "mechanic" friend was just there to help with my issue..Hope you all will understand.
Issue to date: Timing mark will not come down to timing tab in an effort to adjust timing to factory or even 10 degree spec. Timing mark remains at twelve O'Clock position.
What we/I have done:
-I have verified that wires are correct on cap as it relates to position and firing order. Have even attempted to move each wire one position in clockwise direction as well as counterclockwise direction thinking that possibly the distributor is off a tooth in either direction....did not help.
-Verified that vacuum advance mechanism and springs inside on distributor are in working order. Timing will advance when vacuum is reconnected to distributor as well.
- Verified that there is proper vacuum and have attempted on full port on carburetor as well as secondary vacuum port. No change.
-TDC has been verified by taking valve cover off and watching rocker arms to validate TDC on 1st piston on compression stroke. Was told that this is the best way to check for TDC.
- Upon acceleration of engine, timing mark remained at twelve O'Clock position.
I am afraid that the harmonic balancer is indeed bad and would need replacing, but thought I would run this all past this forum before I move in that direction.
tterz
Issue to date: Timing mark will not come down to timing tab in an effort to adjust timing to factory or even 10 degree spec. Timing mark remains at twelve O'Clock position.
What we/I have done:
-I have verified that wires are correct on cap as it relates to position and firing order. Have even attempted to move each wire one position in clockwise direction as well as counterclockwise direction thinking that possibly the distributor is off a tooth in either direction....did not help.
-Verified that vacuum advance mechanism and springs inside on distributor are in working order. Timing will advance when vacuum is reconnected to distributor as well.
- Verified that there is proper vacuum and have attempted on full port on carburetor as well as secondary vacuum port. No change.
-TDC has been verified by taking valve cover off and watching rocker arms to validate TDC on 1st piston on compression stroke. Was told that this is the best way to check for TDC.
- Upon acceleration of engine, timing mark remained at twelve O'Clock position.
I am afraid that the harmonic balancer is indeed bad and would need replacing, but thought I would run this all past this forum before I move in that direction.
tterz
Intermediate
Joined: Nov 2009
Posts: 35
Likes: 0
From: Lancaster SC
Hey tterz, Looking at the rocker to verify the piston is on it's compression stroke is a start but it's not telling you that the piston is at absolute tdc compared to the tdc mark on the balancer. Like Noonie said, you have to physically verify that the piston is actually at tdc and at the end of it's stroke. Never did it with a head on but I imagine it could be done with a pencil end or with a piece of heavier wire bent at the end. Only when you are absolutely sure it's at it's max stroke can you compare it to the tdc mark. Had to replace my balancer due to slipped outer ring and got from, if I remember right Summit, a cover for the balancer that bolts on under the pulley and gives you 90degrees of advance readings along with marks every 90degrees after. Didn't like that it covered the balancer tdc mark so on the cover tdc mark I drilled a 1/2 in. hole so I could compare the two and be able to tell if the balancer ever slipped again. VERIFY piston #1 tdc and go from there.