Timing
Thread Starter
Burning Brakes
Joined: Sep 2001
Posts: 805
Likes: 0
From: College Station / Highland Village TX
Timing
I was helping a friend install a new distibutor in his 68 Camaro the other day, and his dad started doing the timing all of the sudden I was lost. I had no idea what was going on or why. Can someone explain what "timing" is and what its effects are? (Don't forget to pretend I know nothing about cars, all the details help in understanding the subject.) :confused:
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Timing (Chris O')
Timing is everything!!! (pun intened)The spark timing is exact time the spark occurs in the combustion chamber. As speed or RPM increases the spark must be advanced so the spark will occur when the piston gets to the top. Think of it as leading a moving taget. The faster the target moves the more you must lead it. In engines it is done by means of a centrifigal ,vacuum or electronic advance method. There are many variables that affect this but the idea is to have the spark happen at the point where most of the power of the explosion can be used. Too early and the explosion tries to push the piston back down before it is at the top. Too late and the piston has already started down so power is lost. That is basicly how it works.
[Modified by silvervetteman, 5:59 PM 3/19/2002]
[Modified by silvervetteman, 5:59 PM 3/19/2002]
Pro
Joined: Aug 2000
Posts: 708
Likes: 21
From: Montrose CA
Re: Timing (rambler323)
I'll help keep this thread alive...
I started out with the excellent Lars kit in my rebuild and I did crank the advance up to 36-degrees (no vacuum) and drove it through the break in period... All along I thought I heard a little clatter. Now that I have a 1000 miles on the engine I laid into it and really heard the clatter. I went through three cycles of retarding the timing two degrees at a time until the engine runs clean all the way to redline with 30 degrees advance.
The point of all this... The type of engine, the type of parts on the engine, the fuel, the external condition of the engine like engine temp, all contribute to a unique "perfect" ignition timing for each car and each use.
I would like to install one of those ignition controllers to be able to add advance from the cockpit while cruising to match driving conditions. I think I read that MSD controllers allow you to make adjustments on the fly. I understand that modern stock ignition systems have the "knock sensor" that retards timing automatically when too far advanced for the situation.
I have always felt that optimum/aggressive timing was the cheapest source of horsepower on a car... I bet I leaving 20 hp on the table having to retard to 30 degrees!
I started out with the excellent Lars kit in my rebuild and I did crank the advance up to 36-degrees (no vacuum) and drove it through the break in period... All along I thought I heard a little clatter. Now that I have a 1000 miles on the engine I laid into it and really heard the clatter. I went through three cycles of retarding the timing two degrees at a time until the engine runs clean all the way to redline with 30 degrees advance.
The point of all this... The type of engine, the type of parts on the engine, the fuel, the external condition of the engine like engine temp, all contribute to a unique "perfect" ignition timing for each car and each use.
I would like to install one of those ignition controllers to be able to add advance from the cockpit while cruising to match driving conditions. I think I read that MSD controllers allow you to make adjustments on the fly. I understand that modern stock ignition systems have the "knock sensor" that retards timing automatically when too far advanced for the situation.
I have always felt that optimum/aggressive timing was the cheapest source of horsepower on a car... I bet I leaving 20 hp on the table having to retard to 30 degrees!
Safety Car
Joined: Aug 2001
Posts: 3,892
Likes: 13
From: Pettis Performance 565 with two stages of Nitrous Supply nitrous 1.082, 4.61 at 155, 7.17 at 192
Re: Timing (Carl in LA)
I have the adjustible timing control from MSD. I got it so I can retard the timing when I get into the NOS. Yes it works on the fly. I mounted my control **** on the consol in front of the parking brake. Retarding timing helps with top end power. I doubt you cost yourself too much power with that little bit of retard.
Le Mans Master
Joined: Sep 2000
Posts: 5,635
Likes: 4
From: Orlando Floriduh
Re: Timing (Carl in LA)
Carl... I have a stock 427... I chose a little different approach when settig an engine up. I set the initial advance at or a couple of degrees advance @ spec. Then I limt the total advance with bushings, then play with the weights (curve). Then I connect the vacuum advance and back it off if it ping at cruise or light throttle. works great it just takes some time.. Lars has done the homework for us and his kit makes it easy.
Safety Car
Joined: Jan 2001
Posts: 3,569
Likes: 1
From: Hawaii
Re: Timing (rambler323)
Here is a light overview of how it works also with pretty pictures. http://www.howstuffworks.com/ignition-system1.htm
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