timing Q... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

piecesparts · 01-02-2007, 05:19 PM

Pull #1 plug out and rotate the engine until you feel the air coming out of the hole (This should give you a compression stroke), then turn the motor unti the piston is at the top of the cylinder, you can look into the hole or have a small soft stick in the hole to feel the piston top out and then start back down. Tha should be at TDC or real close. Now look at the dizzy for the pointer and where it is at, as well as the harmonic balancer. If it i s not at the pointer than you have probably slipped the timing marks. Are you using the right timing pointer and marks? Different motors have marks in different places. Some are down the front of the motor past the timing chain cover and others are off to the driver's side ot the block. Know where the motor is timed at, first.

Nolowrider · 01-02-2007, 05:51 PM

I see two things that I disagree with.

You want to set the timing THEN adjust your idle. You may have to bump it up some to get her to idle while setting the timing. But, timing first then drop your idle back down..

Why are you putting your balancer at 8*? Put the balancer on 0* then drop your dist in. Rotor points to the #1 lug on the dist, not the plug. They are close but they are a few degrees apart. If you set your balancer at 8*, then your are basically adding 8* mechanical advance. You can drop the dist in on the #1 compression stroke or the exhaust stroke, just drop the dist in accordingly. Meaning when #1 is at TDC drop the dist in pointing to the 1, if it is at BDC drop it in pointing to the #6 lug. That way you don't have to drop a nut rotating the motor, or keep bumping your starter. Both of which are not good. You can pull the valve cover and see what the valves are doing. That will tell you TDC or BDC.

A bouncy or really eratic timing mark is a good indication that the vacuum advance module or the mechanical advance is going bad in the dist.

*Billla* · 01-02-2007, 06:57 PM

I'll respectfully disagree right back

Timing is specified at a set RPM; as you adjust the timing you should continually re-adjust the idle as req'd. It makes no sense to have a high idle with mechanical advance in and trying to set timing.

There's nothing wrong with dropping the distributor to establish initial timing; it's easy to set the engine at whatever you want for static timing and then point the rotor directly at #1. For example, I usually set my engines to 16 degrees BTDC and drop the distributor with the rotor pointing at #1 when starting for the first time - this works fine. If I misunderstood something in your post, my apologies.

Erratic timing can come from many sources and isn't limited to just the advance mechanism IMHO.

Nolowrider · 01-02-2007, 07:51 PM

Quote:

Originally Posted by Billla

I'll respectfully disagree right back

Timing is specified at a set RPM; as you adjust the timing you should continually re-adjust the idle as req'd. It makes no sense to have a high idle with mechanical advance in and trying to set timing.

There's nothing wrong with dropping the distributor to establish initial timing; it's easy to set the engine at whatever you want for static timing and then point the rotor directly at #1. For example, I usually set my engines to 16 degrees BTDC and drop the distributor with the rotor pointing at #1 when starting for the first time - this works fine. If I misunderstood something in your post, my apologies.

Erratic timing can come from many sources and isn't limited to just the advance mechanism IMHO.

Billa- I am not saying that you are wrong, we just do it different ways.

What I am saying is that it is better to set your TOTAL timing and let the iniatial fall where ever it lands. Then adjust the idle.

When you set the balancer off of TDC you are really advancing the cam 6*-8 * not the timing. And with most aftermarket cams they are already ground 4*, so now you are looking at anywhere from 10*-12*. Either way the end result is the same. Either 16* mechanical advance and the narks will be on xero, or line them up on zero and marks show 16*. Same thing.

Vacuum leaks will also lead to eratic timing. Just from wha he posted he didn't elude to any engine problems other than timing. That is why I only that the mech/vacuum advance could be bad.

The engine will run 180* out, just adjust your dist to #6 instead of #1.

*Billla* · 01-02-2007, 08:07 PM

Quote:

Originally Posted by Nolowrider

What I am saying is that it is better to set your TOTAL timing and let the iniatial fall where ever it lands. Then adjust the idle.

Agreed...but that's very different from what I saw you suggesting. Getting to 34-36 degrees total timing requires a degreed balancer or adjustable timing light, and you need increase RPM until all the mechanical is in and then adjust to have it all in by 3000 RPM or so. That's a performance tune...and a bit beyond where we're at in this troubleshooting process IMHO

Nolowrider · 01-02-2007, 08:30 PM

Quote:

Originally Posted by Billla

Agreed...but that's very different from what I saw you suggesting. Getting to 34-36 degrees total timing requires a degreed balancer or adjustable timing light, and you need increase RPM until all the mechanical is in and then adjust to have it all in by 3000 RPM or so. That's a performance tune...and a bit beyond where we're at in this troubleshooting process IMHO

Yeah, maybe I was a little too far ahead of the cart. I agree with ya Billa.

*Billla* · 01-02-2007, 07:06 PM

Quote:

Originally Posted by piecesparts

Pull #1 plug out and rotate the engine until you feel the air coming out of the hole (This should give you a compression stroke), then turn the motor unti the piston is at the top of the cylinder, you can look into the hole or have a small soft stick in the hole to feel the piston top out and then start back down. Tha should be at TDC or real close. Now look at the dizzy for the pointer and where it is at, as well as the harmonic balancer. If it i s not at the pointer than you have probably slipped the timing marks. Are you using the right timing pointer and marks? Different motors have marks in different places. Some are down the front of the motor past the timing chain cover and others are off to the driver's side ot the block. Know where the motor is timed at, first.

I think you have too many variables here. Make sure you've got the balancer on TDC compression #1 and then back off to your advanced timing setting and drop the distributor pointing at the #1 tower. I wouldn't stick anything other than a piston stop in the hole IMHO - it would suck to have a piece of soft stick in the bore

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01-02-2007, 05:51 PM	#2
Nolowrider Senior Member Join Date: Jan 2005 Location: New Orleans Posts: 1,365	Re: timing Q... I see two things that I disagree with. You want to set the timing THEN adjust your idle. You may have to bump it up some to get her to idle while setting the timing. But, timing first then drop your idle back down.. Why are you putting your balancer at 8? Put the balancer on 0 then drop your dist in. Rotor points to the #1 lug on the dist, not the plug. They are close but they are a few degrees apart. If you set your balancer at 8, then your are basically adding 8 mechanical advance. You can drop the dist in on the #1 compression stroke or the exhaust stroke, just drop the dist in accordingly. Meaning when #1 is at TDC drop the dist in pointing to the 1, if it is at BDC drop it in pointing to the #6 lug. That way you don't have to drop a nut rotating the motor, or keep bumping your starter. Both of which are not good. You can pull the valve cover and see what the valves are doing. That will tell you TDC or BDC. A bouncy or really eratic timing mark is a good indication that the vacuum advance module or the mechanical advance is going bad in the dist. Last edited by Nolowrider; 01-02-2007 at 05:55 PM.

01-02-2007, 06:57 PM	#3
Billla Account Suspended Join Date: Sep 2005 Location: Monroe, WA Posts: 3,814	Re: timing Q... I'll respectfully disagree right back Timing is specified at a set RPM; as you adjust the timing you should continually re-adjust the idle as req'd. It makes no sense to have a high idle with mechanical advance in and trying to set timing. There's nothing wrong with dropping the distributor to establish initial timing; it's easy to set the engine at whatever you want for static timing and then point the rotor directly at #1. For example, I usually set my engines to 16 degrees BTDC and drop the distributor with the rotor pointing at #1 when starting for the first time - this works fine. If I misunderstood something in your post, my apologies. Erratic timing can come from many sources and isn't limited to just the advance mechanism IMHO. Last edited by Billla; 01-02-2007 at 07:03 PM.

01-02-2007, 05:19 PM	#1
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Re: timing Q... Pull #1 plug out and rotate the engine until you feel the air coming out of the hole (This should give you a compression stroke), then turn the motor unti the piston is at the top of the cylinder, you can look into the hole or have a small soft stick in the hole to feel the piston top out and then start back down. Tha should be at TDC or real close. Now look at the dizzy for the pointer and where it is at, as well as the harmonic balancer. If it i s not at the pointer than you have probably slipped the timing marks. Are you using the right timing pointer and marks? Different motors have marks in different places. Some are down the front of the motor past the timing chain cover and others are off to the driver's side ot the block. Know where the motor is timed at, first.



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