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Old 06-28-2008, 05:34 PM
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Beating a dead horse, Timing help please

I know I have been through this with you guys but I am having trouble timing my sbc. Its a 355 with a good cam and headers,holley double pumper,rpm intake. I am confused with the timing process. At idle I want 8-12 advanced and then 34-36 total at 3000rpm? I am confused at how I get these numbers.

Earlier today I went out and set my timing light to 10 advanced and found 0 on the timing tab. (i have an advanced timing light). So do I add 26 more to that when I rev it to 3000 to get my 36 degrees total? Or do I just bring the rpm's up to 3000 and then set it right a 36 degrees. I am not using my vacuum advanced, I have the vacuum port plugged also. I guess my question is how do I get my initial and my advanced? Do I add two numbers together to get my total 36 degrees?

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Old 06-28-2008, 06:36 PM
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To be able to get those numbers which are OK you have to have the correct numbers in the distributer, in your case 26 degrees. Since your is blocked you don't need to pull off the vacuum advance hose and block it at the carb and then start your motor and bring it up to 3000 rpm. you should have 36 degrees set on your timing light and then use the tab at 0. That's the total. Next try and see what the idle timing is now with the vacuum still disconnected. Should be 10 degrees if there is 26 degrees in the distributer.
Now comes the trickey part. reconnect the vacuum line see what the numbers are now. Some cars drive lot better with vacuum advance.
I guess the easiest thing is drive the car. I like to run higher total degrees and still be able to have the motor crank off OK without "riding" the starter. The deciding factor is to run the most timing you can without spark knock under load and still have the motor start easily when warm. The numbers depend on gas octane and static compression of the motor.

Last edited by garyroushkolb; 06-28-2008 at 06:40 PM. Reason: spelling
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Old 06-28-2008, 06:43 PM
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So at idle I set it at 10 degrees? And at 3000rpm I add 26 more? For a total of 36 degrees?
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Old 06-28-2008, 10:13 PM
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A stock GM dist will have about 22 to 26 degs of mechanical advance. Get a curve kit and install the springs that will give you max advance between 2800 and 3 grand. Set the total at 36 @ 3 grand and forget about the initial. Where it is....it is.
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Old 06-28-2008, 10:58 PM
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Various types of spring only vary how quick the timing comes in not the degrees.
If you donīt have a distributor with adjustable weights you wonīt be able to limit the amount of total timing.
Look at these MSD instructions they show how springs and bushings are used to tailor a timing curve.
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Old 06-28-2008, 11:09 PM
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Its an hei. I just want this thing timed so I can drive it to the exhaust shop to get some pipes hooked up. I will be driving open headers. I would rather not put any money into and hei. If I change anything with the hei it will be getting tossed out for a billet unit.
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Old 06-29-2008, 12:21 AM
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At the moment I have an HEI/MSD ignition box and my initial is 16š.
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Old 06-29-2008, 09:58 AM
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So I would be okay with just setting it to 36 degrees at 3000rpm and letting the initial fall wherever it wants?
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Old 06-29-2008, 11:02 AM
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Set your timing light to 36 degrees and rev the engine to anywhere around 3000 rpm, over or under, while looking at your timing. Once the timing does not advance any more, adjust your timing light until it lines up with zero. This will let you know how much advance is built into the distributor, and at what rpm it is at the maximum advance. This is best checked with a hand held tach hooked up.

Once you know at what rpm you are getting your maximum advance, and how much advance you have, then you can set your distributor to 36 degrees(I like to set them at 38 degrees) by reseting your timing light to 36 degrees, and revving the engine over the maximum advance rpm, and turn the distributor to line up the timing to the zero mark. This will set your maximum mechanical timing at 36 degrees.

Now at idle check your new base timing, and make a note of it. This is when you will want to hook up your vacuum advance to manifold vacuum, and adjust your idle speed and idle mixture screws.
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Old 07-07-2008, 11:31 PM
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So at the rpm that it stops advancing, I set the timing there to 36 degrees?
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Old 07-07-2008, 11:48 PM
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Quote:
Originally Posted by scapegoat
So at the rpm that it stops advancing, I set the timing there to 36 degrees?
Yes. Between 36-38 is good. Just make sure all of your "centrifugal" (mechanical) advance is in full at the rpm.
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Old 07-08-2008, 01:03 AM
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Read through this, The Spin Doctor
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Old 07-08-2008, 04:44 AM
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I agree with MALC totally. This is a great article and explains what everyone here is trying to say. Boiled down I think I'd set it at 36 at 3,000 and forget the rest if the dist is in good shape.
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Old 07-08-2008, 11:34 PM
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Well I have been driving the truck for a few days and it has been running okay. I went to time it today and I got a little confused.

Bare with me here. I set my timing light at 36 degrees and revved the engine until it stopped advancing mechanically, around three grand. I then turned the distributor to where it wanted to be for my 36 degrees. Where I needed the timing mark on the balancer to be with the zero on the timing tab, the engine would pop through the carb. I think there is some issue with either my balancer or my timing tab. It is an old balancer. Do you think the outer hub slipped? I'll see if I can get a picture of the balancer.

The balancer hub is 2-3/4" thick and the diameter is 6-3/4". I have marked in the picture where the keyway for the crank is and where the timing line on the balancer is. Are these supposed to be where they are in the picture.
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Old 07-09-2008, 12:22 AM
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Quote:
Originally Posted by scapegoat
Well I have been driving the truck for a few days and it has been running okay. I went to time it today and I got a little confused.

Bare with me here. I set my timing light at 36 degrees and revved the engine until it stopped advancing mechanically, around three grand. I then turned the distributor to where it wanted to be for my 36 degrees. Where I needed the timing mark on the balancer to be with the zero on the timing tab, the engine would pop through the carb. I think there is some issue with either my balancer or my timing tab. It is an old balancer. Do you think the outer hub slipped? I'll see if I can get a picture of the balancer.

The balancer hub is 2-3/4" thick and the diameter is 6-3/4". I have marked in the picture where the keyway for the crank is and where the timing line on the balancer is. Are these supposed to be where they are in the picture.
Here's some Info on balancers.
http://www.chevytech.com/2c44.html
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