Timing
Thread Starter
Race Director
Joined: Oct 2000
Posts: 17,102
Likes: 7
From: Fair Oaks, OK
Timing
I got out the trusty timing light to day and set the timing on my car with my dad's help. We set it to the factory recommended 8° BTDC initial with the engine at 700 rpm and the vaccuum advance unplugged.
I don't think the car accellerates as well now as it did before. When we first hooked the gun up, it was advanced so much at 700 rpm that the mark was not even on the scale, but the idle was good and the car ran very strong above 3,000 rpm. It just had no guts off the line, and I was hoping timing was the cause. Now it seems to be a little better off the line, but not as powerful at higher rpms.
I do not have an advance timing light, so I had no way to set for max advance at x rpm. Are there any other things that may not be working properly that would cause the car to run worse at factory recommended initial timing? Does it sound like my vaccuum advance is not working properly?
I don't think the car accellerates as well now as it did before. When we first hooked the gun up, it was advanced so much at 700 rpm that the mark was not even on the scale, but the idle was good and the car ran very strong above 3,000 rpm. It just had no guts off the line, and I was hoping timing was the cause. Now it seems to be a little better off the line, but not as powerful at higher rpms.
I do not have an advance timing light, so I had no way to set for max advance at x rpm. Are there any other things that may not be working properly that would cause the car to run worse at factory recommended initial timing? Does it sound like my vaccuum advance is not working properly?
Melting Slicks
Joined: Feb 2000
Posts: 3,052
Likes: 0
From: Vancouver BC, Canada
is the vacuum advance at a ported or full source? it shouldn't matter thought at WOT, but off-idle transition is affected.
was the advance connected when you took your baseline reading?
an investment in an adjustable timing light is a requirement to tune your car for max performance IMO.
was the advance connected when you took your baseline reading?
an investment in an adjustable timing light is a requirement to tune your car for max performance IMO.
Last edited by Turbo-Jet; Jul 28, 2004 at 04:54 AM.
Racer
Joined: Mar 2004
Posts: 484
Likes: 0
From: Guston KY
Read Lars timing paper.
8* is not much.
Get some lighter advance springs.
Make sure that your weights are not rusted or gumed up, etc. and that you are getting full advance.
This was 1 of the many issues with mine.
8* is not much.
Get some lighter advance springs.
Make sure that your weights are not rusted or gumed up, etc. and that you are getting full advance.
This was 1 of the many issues with mine.
Burning Brakes
Joined: Jun 2002
Posts: 792
Likes: 2
From: Norcross GA
The ideal is 36 degrees of mechanical advance by about 3,000 rpm. This requires some adjustment by changing the springs and weights to get there. For example, before I changed out my distributor and messing with the springs, I had about 20 degrees at 3,000 rpm. I know have 36 degrees at 3,000 rpm, just as recommended.
What has happened with your car is that by turning back the advance to 8 degrees, you have changed the amount of total advance that is in at lower rpm by whatever degree change you made to the initial timing. For example, if you were at 16 degrees at idle before and went back 8 degrees you have reduced your total advance by that amount and you are feeling it in the power curve.
Get your self some weights and a dial back timing light. You'll be able to start off at 8 degrees and get the total timing necessary for the small block very easily.
Bob
What has happened with your car is that by turning back the advance to 8 degrees, you have changed the amount of total advance that is in at lower rpm by whatever degree change you made to the initial timing. For example, if you were at 16 degrees at idle before and went back 8 degrees you have reduced your total advance by that amount and you are feeling it in the power curve.
Get your self some weights and a dial back timing light. You'll be able to start off at 8 degrees and get the total timing necessary for the small block very easily.
Bob
Le Mans Master
Joined: Mar 2002
Posts: 6,217
Likes: 1
From: End of the Ike IL
Cruise-In V Veteran
Cruise-In VI Veteran
Harbor Freight has advance inductive timing lights for $29.99.
After recurving per Lars' paper, I ended up at 12* initial, 8* more than factory specs. Runs excellently.
Get an advance timing light- makes life easier...
After recurving per Lars' paper, I ended up at 12* initial, 8* more than factory specs. Runs excellently.
Get an advance timing light- makes life easier...
Pro
Joined: Sep 2002
Posts: 690
Likes: 1
From: near Memphis TN
Everyone gave you good advice. The key is don't even really worry about the initial, worry about the timing curve and the total so that the total is in, as some one said, at about 36 degrees at around 2,800-3,000 RPM. Change the springs out if you need to get that quick curve in. Also, hook the vacuum advance back up after you set the timing.
The initial can be anywhere between 4 and 16 or so (anymore than that an you may have a hard time starting the car).
The initial can be anywhere between 4 and 16 or so (anymore than that an you may have a hard time starting the car).
Le Mans Master
Joined: Mar 2004
Posts: 7,423
Likes: 1,458
From: Little Rock AR
If you don't want to buy a dial back timing light, you can just mark a line with a sharpie at 36° and use a standard light. It is much more accurate than a cheapie dial back light and free to boot.
You start by using a measuring tape to record the circumference of the balancer. If your balancer is say 25" around, the 36° mark would be 1/10th of the circumference (2.5") away from the zero on the balancer. (It is to the right of the zero mark on the balancer). You need to actualy measure YOUR balancer circumference because the circumference will vary depending on the size of your balancer.
Once you have the mark, you plug the vacuum advance and rev the engine untill the centrifugal advance is all in (maybe 3000 to 4000 rpm, where ever it stops advancing) and line up the sharpie mark with the zero on the timing tab then lock the distributor down. You have set your timing to 36° at the top of the curve that way instead of setting it at idle. That is it.
-Mark.
You start by using a measuring tape to record the circumference of the balancer. If your balancer is say 25" around, the 36° mark would be 1/10th of the circumference (2.5") away from the zero on the balancer. (It is to the right of the zero mark on the balancer). You need to actualy measure YOUR balancer circumference because the circumference will vary depending on the size of your balancer.
Once you have the mark, you plug the vacuum advance and rev the engine untill the centrifugal advance is all in (maybe 3000 to 4000 rpm, where ever it stops advancing) and line up the sharpie mark with the zero on the timing tab then lock the distributor down. You have set your timing to 36° at the top of the curve that way instead of setting it at idle. That is it.
-Mark.
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