distributor/timing problem - need solution
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
distributor/timing problem - need solution
o.k. 79 L82. modified by previous owner with aluminum L98 heads and headers with true dual exhaust. i've added digital ignition. other wise, engine stock as far as i know. has always been sluggish on bottom end. starts and runs "o.k." although seems to require excessive warm up time to idle cold (will die on cold start up in idle unless choke in and running on high idle cam for several minutes, even in hot weather). once warm runs o.k. and cruises well.
after reading some posts here decided to check TDC position of rotor. I put timing mark dead on TDC mark on balancer, pulled the distributor cap and to my surprise found the rotor pointing about halfway between #1 and #8 terminal?!?!?! WTF!!!!
How do I determine the exact problem here? without chasing my tail. how do I determine if the time marks have slipped, if the distributor is off a gear or if timing chain has jumped a gear?
like i said, it starts o.k. but has the above mentioned performance problems. i run 16 degrees intial advance with 36 all in by 2500 now. BUT apparently that's not what i've really got, is it?
what should i do to fix this? thanks for any input.
after reading some posts here decided to check TDC position of rotor. I put timing mark dead on TDC mark on balancer, pulled the distributor cap and to my surprise found the rotor pointing about halfway between #1 and #8 terminal?!?!?! WTF!!!!
How do I determine the exact problem here? without chasing my tail. how do I determine if the time marks have slipped, if the distributor is off a gear or if timing chain has jumped a gear?
like i said, it starts o.k. but has the above mentioned performance problems. i run 16 degrees intial advance with 36 all in by 2500 now. BUT apparently that's not what i've really got, is it?
what should i do to fix this? thanks for any input.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
To determine if your balancer outer ring has slipped you'll need to determine TDC exactly.
1) pull all plugs and insert a piston stop in #1.
2) Gently rotate engine by hand until the #1 piston just touchs the stop. Make a thin mark on balancer directly across from the 0* mark on the timing tab.
3) Gently rotate the engine in the opposite direction until the piston again just touchs the stop. Make another thin mark on the balancer.
4) Make a 3rd mark on the balancer exactly 1/2 the distance between the 1st two marks. This is your true TDC.
1) pull all plugs and insert a piston stop in #1.
2) Gently rotate engine by hand until the #1 piston just touchs the stop. Make a thin mark on balancer directly across from the 0* mark on the timing tab.
3) Gently rotate the engine in the opposite direction until the piston again just touchs the stop. Make another thin mark on the balancer.
4) Make a 3rd mark on the balancer exactly 1/2 the distance between the 1st two marks. This is your true TDC.
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,402
From: At my Bar drinking and wrenching in Lafayette Colorado
Sounds normal to me. At TDC, the rotor should be past the #1 terminal and on its way to number 8. Keep in mind that the ignition fires anywhere from 10 to 54 degrees in advance of TDC - it does not fire at TDC. I think your setup sounds normal and correct.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by marshrat99
To determine if your balancer outer ring has slipped you'll need to determine TDC exactly.
1) pull all plugs and insert a piston stop in #1.
2) Gently rotate engine by hand until the #1 piston just touchs the stop. Make a thin mark on balancer directly across from the 0* mark on the timing tab.
3) Gently rotate the engine in the opposite direction until the piston again just touchs the stop. Make another thin mark on the balancer.
4) Make a 3rd mark on the balancer exactly 1/2 the distance between the 1st two marks. This is your true TDC.
1) pull all plugs and insert a piston stop in #1.
2) Gently rotate engine by hand until the #1 piston just touchs the stop. Make a thin mark on balancer directly across from the 0* mark on the timing tab.
3) Gently rotate the engine in the opposite direction until the piston again just touchs the stop. Make another thin mark on the balancer.
4) Make a 3rd mark on the balancer exactly 1/2 the distance between the 1st two marks. This is your true TDC.
This is the way to be sure.I also agree with Lars -it is a normal position for the rotor to be in.
Also performance timing is just shy of pinging-does it ping? If you bump it up a few degrees does it ping if so your in good shape.
Thread Starter
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: San Antonio Texas
Originally Posted by lars
Sounds normal to me. At TDC, the rotor should be past the #1 terminal and on its way to number 8. Keep in mind that the ignition fires anywhere from 10 to 54 degrees in advance of TDC - it does not fire at TDC. I think your setup sounds normal and correct.
Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by greyghost79
so, the initial timing i have is resulting in the rotor being past #1 terminal at TDC, correct? if I set initial timing to 0 degrees then the rotor should point directly at #1, is that right?
Drifting
Joined: Feb 2005
Posts: 1,583
Likes: 5
From: Richardson Tx.
Originally Posted by DWncchs
This is the way to be sure.I also agree with Lars -it is a normal position for the rotor to be in.
Also performance timing is just shy of pinging-does it ping? If you bump it up a few degrees does it ping if so your in good shape.
So what is better for performance- set total timing to a certain pre-determined number like 36 degrees --- Or set timing with your ears (ping minus 2 degrees - wherever this may fall in total timing degrees) ?
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Race Director
Joined: May 2006
Posts: 16,528
Likes: 53
From: Dayton, Ohio
Originally Posted by 79vetter
So what is better for performance- set total timing to a certain pre-determined number like 36 degrees --- Or set timing with your ears (ping minus 2 degrees - wherever this may fall in total timing degrees) ?