Timing light advance measurement doesn't stop

[tony-muscle]

Today I was testing my newly installed 408 stroker. I am using the OEM distributor that I had recently disassembled and cleaned. The distributor has the 10L slot that should be good for 20 degrees advance. The initial timing is at 12. The weird situation is that as I go up in RPM the advancing seems to never stop. It went all the way to 50 before I lower the RPMs. I don't know if it will stop at 50 but I just didn't want to go any higher. Upon return to idle the timing was back at 12. Tested several time with the same outcome. I have the feeling that something may be wrong with the timing light because it doesn't seem to make sense. I think the engine won't be able to run with a real 50 advance. When I had it running with "50" advance it sounded and run fine. Does anyone have an idea of what am I doing wrong? Could it be a setting of the timing light?

Edit: I did have the vacuum disconnected.

 

[Don C]

I would take the cap off and turn the rotor by hand, see if it stops where it should, to rule out a problem with the advance mechanism. If that is OK, then it has to be the timing light. Do you have another timing light that doesn't have the advance feature?

 

[tony-muscle]

I would take the cap off and turn the rotor by hand, see if it stops where it should, to rule out a problem with the advance mechanism. If that is OK, then it has to be the timing light. Do you have another timing light that doesn't have the advance feature?

I rotated it and stops after a small rotation. I tested that before putting the cap in. I will have to recheck. Once I go back home I will dig the instructions of the timing light to see if there is some weird feature that is on.

 

[tony-muscle]

A thought. I have a Street Fire (by MSD) CD ignition box. Could the multiple spark of the CD ignition fool the timing light somehow?

 

[c9zx]

Is the OEM vacuum advance connected? If so it can add 15+ degrees of additional advance. Chuck

 

[tony-muscle]

Is the OEM vacuum advance connected? If so it can add 15+ degrees of additional advance. Chuck

The vacuum canister is on, but with the hose disconnected.

 

[c9zx]

If it is a dial back timing light, set it on zero. They have been known to give false readings due to the potentiometer being less than perfect. Chuck

 

[tony-muscle]

Checked the distributor and all looks good. I can rotate the rotor slightly until it stops and then springs back. I didn't measure but it is a very small movement. The breaker plate is attached to the vacuum advance arm and it is very tight.

I will check timing again this weekend making sure that the pickup clip is separated from the other wires and revving it past 3,000 RPM, which from what I understand is the RPMs at which the CD stops.

 

[Stanglover]

When I did mine and I'm sure you've read my saga on timing issues, I had a similar thing happening. That's when I started playing with the springs and tension. For sure I think it could be your timing light, so try another if you can.

What springs are you using? You have a good base imo, with the 10L slot, but to control the rate of advance needs spring tweaking. On MY engine, I found the factory heavy spring, set on the pegs with only slight free-paly and a Mr. Gasket 925D spring on the other pegs, worked best for me. Also, my vacuum advance canister is adjustable and I turned it back to give only 4-6 degrees of vac advance. Also, don't forget to plug your vac line when you disconnect it, made that mistake before!

My numbers are; 10L slot, 20 deg. crank, 16 deg. initial, 4-6 deg. vac adv. and springs as mentioned. My result is a strong pulling motor, no rattle.

Now, I realize your motor at 408 may change things beyond anything I know (which ain't much!!), so hopefully you'll get it figured out. Be sure to let me/us know.

Good luck,

Geoff.

 

[tony-muscle]

When I did mine and I'm sure you've read my saga on timing issues, I had a similar thing happening. That's when I started playing with the springs and tension. For sure I think it could be your timing light, so try another if you can.

What springs are you using? You have a good base imo, with the 10L slot, but to control the rate of advance needs spring tweaking. On MY engine, I found the factory heavy spring, set on the pegs with only slight free-paly and a Mr. Gasket 925D spring on the other pegs, worked best for me. Also, my vacuum advance canister is adjustable and I turned it back to give only 4-6 degrees of vac advance. Also, don't forget to plug your vac line when you disconnect it, made that mistake before!

My numbers are; 10L slot, 20 deg. crank, 16 deg. initial, 4-6 deg. vac adv. and springs as mentioned. My result is a strong pulling motor, no rattle.

Now, I realize your motor at 408 may change things beyond anything I know (which ain't much!!), so hopefully you'll get it figured out. Be sure to let me/us know.

Good luck,

Geoff.

I followed your advice as a starting point. I am using one from the Mr. Gasket set with the lightest of the two springs that were on the distributor (but it was heavier than the Mr. Gasket). Since I am reading up to 50 advance without vacuum connected I can only think that it is timing light issue. I don't have another a timing light. I may have to borrow one if the problem persists.

 

[Stanglover]

When I did mine and I'm sure you've read my saga on timing issues, I had a similar thing happening. That's when I started playing with the springs and tension. For sure I think it could be your timing light, so try another if you can.

What springs are you using? You have a good base imo, with the 10L slot, but to control the rate of advance needs spring tweaking. On MY engine, I found the factory heavy spring, set on the pegs with only slight free-paly and a Mr. Gasket 925D spring on the other pegs, worked best for me. Also, my vacuum advance canister is adjustable and I turned it back to give only 4-6 degrees of vac advance. Also, don't forget to plug your vac line when you disconnect it, made that mistake before!

My numbers are; 10L slot, 20 deg. crank, 16 deg. initial, 4-6 deg. vac adv. and springs as mentioned. My result is a strong pulling motor, no rattle.

Now, I realize your motor at 408 may change things beyond anything I know (which ain't much!!), so hopefully you'll get it figured out. Be sure to let me/us know.

Good luck,

Geoff.

I followed your advice as a starting point. I am using one from the Mr. Gasket set with the lightest of the two springs that were on the distributor (but it was heavier than the Mr. Gasket). Since I am reading up to 50 advance without vacuum connected I can only think that it is timing light issue. I don't have another a timing light. I may have to borrow one if the problem persists.

 For sure try another T/light. It is a process of elimination now, one thing after another.

 If it helps, here is a pic of my springs, but you've seen it before I'm sure. Are you using points or a Pertonix II and matching coil. I found the Pertronix the best solution.

 

[tony-muscle]

When I did mine and I'm sure you've read my saga on timing issues, I had a similar thing happening. That's when I started playing with the springs and tension. For sure I think it could be your timing light, so try another if you can.

What springs are you using? You have a good base imo, with the 10L slot, but to control the rate of advance needs spring tweaking. On MY engine, I found the factory heavy spring, set on the pegs with only slight free-paly and a Mr. Gasket 925D spring on the other pegs, worked best for me. Also, my vacuum advance canister is adjustable and I turned it back to give only 4-6 degrees of vac advance. Also, don't forget to plug your vac line when you disconnect it, made that mistake before!

My numbers are; 10L slot, 20 deg. crank, 16 deg. initial, 4-6 deg. vac adv. and springs as mentioned. My result is a strong pulling motor, no rattle.

Now, I realize your motor at 408 may change things beyond anything I know (which ain't much!!), so hopefully you'll get it figured out. Be sure to let me/us know.

Good luck,

Geoff.

I followed your advice as a starting point. I am using one from the Mr. Gasket set with the lightest of the two springs that were on the distributor (but it was heavier than the Mr. Gasket). Since I am reading up to 50 advance without vacuum connected I can only think that it is timing light issue. I don't have another a timing light. I may have to borrow one if the problem persists.

 For sure try another T/light. It is a process of elimination now, one thing after another.

 If it helps, here is a pic of my springs, but you've seen it before I'm sure. Are you using points or a Pertonix II and matching coil. I found the Pertronix the best solution.

Pertronix II with MSD 2 coil. The Pertronix II came with the car so I don't know how old is it.

Here is a picture of my spring setup:

 

[Fabrice]

Not related to your problem, I wonder why you have springs of different sizes. If the principle is same as on the autolite that I've restored a few weeks back, they both have impact on centrifugal force, each spring responsible for one weight but both connected to one input shaft and rotating on single plate in the end. Above a certain rpm, say 3k, the centrifugal force exceeds the spring force and the springs expend. Now on your setup one weight will be extended, the weight more out at different rpm. As the resulting rotation is the combined force of the two. I think the idea behind is to create a curve to replace the linear evolution from min to max advance during RPM increase /decrease. But because forces are combined to rotate the same plate why not using springs of same force but from different type (metal/coils count) to prevent wear by being out of balance?

Please educate me! (when your issue will be fixed)

 

[Stanglover]

I followed your advice as a starting point. I am using one from the Mr. Gasket set with the lightest of the two springs that were on the distributor (but it was heavier than the Mr. Gasket). Since I am reading up to 50 advance without vacuum connected I can only think that it is timing light issue. I don't have another a timing light. I may have to borrow one if the problem persists.

 For sure try another T/light. It is a process of elimination now, one thing after another.

 If it helps, here is a pic of my springs, but you've seen it before I'm sure. Are you using points or a Pertonix II and matching coil. I found the Pertronix the best solution.

Pertronix II with MSD 2 coil. The Pertronix II came with the car so I don't know how old is it.

Here is a picture of my spring setup:

Tony, Do I see the problem? in this pic, the weights are under the slot/cam plate. Is this correct now? If the weights are not located properly you'll never get it to time.

Also the weights need to be the same from the info I have from Cardone.

I'm not the expert here, but from my own findings, your heavy spring is under tension, mine is just slightly loose as this controls the last bit of the curve to 3000 rpm.

Please double check and let us know. Also, I don't know what voltage rating that MSD coil is compared to the Pertronix II coil. Might be worth checking. It all needs to work together.

 

[Jeff73Mach1]

Try a different timing light-many can't handle multi spark ignitions

 

[Stanglover]

Not related to your problem, I wonder why you have springs of different sizes. If the principle is same as on the autolite that I've restored a few weeks back, they  both have impact on centrifugal force, each spring responsible for one weight but both connected to one input shaft and rotating on single plate in the end. Above a certain rpm, say 3k, the centrifugal force exceeds the spring force and the springs expend. Now on your setup one weight will be extended, the weight more out at different rpm. As the resulting rotation is the combined force of the two. I think the idea behind is to create a curve to replace the linear evolution from min to max advance during RPM increase /decrease. But because forces are combined to rotate the same plate why not using springs of same force but from different type (metal/coils count) to prevent wear by being out of balance?

Please educate me! (when your issue will be fixed)

 Again from my mega knowledge, the factory distributor came with 1 heavy and 1 lighter spring. (as do the aftermarket repops) The idea being (I believe) that the light spring controls the initial advance and the heavy controls the final advance and sets the final all-in rpm for advance. For sure the light spring weight will be fully rotated, but the other will still not be fully rotated until the centrifugal force overcomes that spring.

I played around with weight, springs and tension quite a bit before hitting the sweetspot on my 351C 4 V manual trans.

 I stress this is just from what I found to work and may not necessarily be the total answer. Others may have differing ideas.

Geoff.

 

[tony-muscle]

 For sure try another T/light. It is a process of elimination now, one thing after another.

 If it helps, here is a pic of my springs, but you've seen it before I'm sure. Are you using points or a Pertonix II and matching coil. I found the Pertronix the best solution.

Pertronix II with MSD 2 coil. The Pertronix II came with the car so I don't know how old is it.

Here is a picture of my spring setup:

Tony, Do I see the problem? in this pic, the weights are under the slot/cam plate. Is this correct now? If the weights are not located properly you'll never get it to time.

Also the weights need to be the same from the info I have from Cardone.

I'm not the expert here, but from my own findings, your heavy spring is under tension, mine is just slightly loose as this controls the last bit of the curve to 3000 rpm.

Please double check and let us know. Also, I don't know what voltage rating that MSD coil is compared to the Pertronix II coil. Might be worth checking. It all needs to work together.

I am not understanding what you mean that the weights are under the slot/cam plate. Can you please explain?

I just realized that this picture was taken before the springs were replaced so this is how it was not how it is. However, the location of the weights has not changed. I only replaced the springs and straighten the tab where the stretched spring is in the picture (right side of pictures).

 

[tony-muscle]

Try a different timing light-many can't handle multi spark ignitions

I need to do that. I want to test once more at about 3,000+ rpm which is when approximately the multiple sparks go down to one spark. It is kind of nerve racking running the engine seeing 50 advance, but I know this can't be true. During the test drive I run it at 4,000 rpms and it felt very good.

 

[Stanglover]

Pertronix II with MSD 2 coil. The Pertronix II came with the car so I don't know how old is it.

Here is a picture of my spring setup:

Tony, Do I see the problem? in this pic, the weights are under the slot/cam plate. Is this correct now? If the weights are not located properly you'll never get it to time.

Also the weights need to be the same from the info I have from Cardone.

I'm not the expert here, but from my own findings, your heavy spring is under tension, mine is just slightly loose as this controls the last bit of the curve to 3000 rpm.

Please double check and let us know. Also, I don't know what voltage rating that MSD coil is compared to the Pertronix II coil. Might be worth checking. It all needs to work together.

I am not understanding what you mean that the weights are under the slot/cam plate. Can you please explain?

I just realized that this picture was taken before the springs were replaced so this is how it was not how it is. However, the location of the weights has not changed. I only replaced the springs and straighten the tab where the stretched spring is in the picture (right side of pictures).

 Tony, it may just be that picture is out of date, but look at mine. In your pic, the weights are under the slot/cam plate, the weights should be within the cam part of that plate. As you say though, you realized this is not the picture you probably meant to post.

This latest pic is just to shows where the cam weights locate. I'm sure you know this already, but just to save any confusion.

Geoff.