[Rocky Rotella]

The Moroso points weights are shaped like the originals. The HEI weights and center plate aren’t even close. If it were me, I’d choose the originals over the aftermarket weights and use the kit for the spring (and limiting bushing) only. If used original weights aren’t available, I’m sure the Moroso weights would suffice.

[67gtospud]

Originally Posted by Rocky Rotella

The Moroso points weights are shaped like the originals. The HEI weights and center plate aren’t even close. If it were me, I’d choose the originals over the aftermarket weights and use the kit for the spring (and limiting bushing) only. If used original weights aren’t available, I’m sure the Moroso weights would suffice.

Do you have a part number for the points kit? I might as well get the weights just in case I need them.

[Rocky Rotella]

Sure thing!

It’s 72310. I don’t think our host carries it. You might try Summit or Jegs.

[67gtospud]

Originally Posted by Rocky Rotella

Sure thing!

It’s 72310. I don’t think our host carries it. You might try Summit or Jegs.

Thank you!

I know this question is open to opinion and will vary, but is 25-2600rpm a good goal to be all in with my timing? Or should I aim to be closer to 3000? My engine combo is in my signature for reference to my particular setup.

[Rocky Rotella]

I haven’t had good luck trying to get full advance by 2,500-2,600 rpm. Generally speaking, the springs have to be pretty light tension to achieve it, and that creates a problem where the springs aren’t capable of fully retracting the weights at idle speed. You end up with a few degrees hanging out there and erratic idle speed.

I generally shoot for a starting point between 800 and 1,200 rpm (depending upon the particular combo) and full advance between 3,200 to 3,600 rpm. The shape of the center plate works in concert with the springs and has a direct effect on advance rate. A smooth advance curve is a little tougher to achieve with points distributors because you can’t easily change the center plate since it’s permanently fixed to the main shaft. HEI’s are simpler because you can replace the center plate, weights and springs on any unit to achieve the desired amount.

With as quickly as a good running engine passes from 2,600 to say, 3,400 rpm, you’re probably not going to notice a performance difference.

[lust4speed]

Today's gas pretty much dictates a slower advance curve than what we wanted in the 60's. I never set a street distributor up for full advance before 3,000 and some engines want up to 3,400 RPM or above. Sometimes that midrange roll-on on a hot summer day just isn't happy with a faster curve.

Also agree with stock weights being much better. Most aftermarket weights are soft steel and stamped out without much care of the finished product. Stock weights are usually heavier and the curve on the distributor machine just looks much better with them. I have my friends buy the kits when I work on their distributors and then I clean up the original weights and use them with the aftermarket springs.

[67gtospud]

Originally Posted by Rocky Rotella

I haven’t had good luck trying to get full advance by 2,500-2,600 rpm. Generally speaking, the springs have to be pretty light tension to achieve it, and that creates a problem where the springs aren’t capable of fully retracting the weights at idle speed. You end up with a few degrees hanging out there and erratic idle speed.

I generally shoot for a starting point between 800 and 1,200 rpm (depending upon the particular combo) and full advance between 3,200 to 3,600 rpm. The shape of the center plate works in concert with the springs and has a direct effect on advance rate. A smooth advance curve is a little tougher to achieve with points distributors because you can’t easily change the center plate since it’s permanently fixed to the main shaft. HEI’s are simpler because you can replace the center plate, weights and springs on any unit to achieve the desired amount.

With as quickly as a good running engine passes from 2,600 to say, 3,400 rpm, you’re probably not going to notice a performance difference.

Originally Posted by lust4speed

Today's gas pretty much dictates a slower advance curve than what we wanted in the 60's. I never set a street distributor up for full advance before 3,000 and some engines want up to 3,400 RPM or above. Sometimes that midrange roll-on on a hot summer day just isn't happy with a faster curve.

Also agree with stock weights being much better. Most aftermarket weights are soft steel and stamped out without much care of the finished product. Stock weights are usually heavier and the curve on the distributor machine just looks much better with them. I have my friends buy the kits when I work on their distributors and then I clean up the original weights and use them with the aftermarket springs.

This is all great info! I would assume that heavier weights would also sling out quicker thus causing timing to come in faster. Would it be acceptable if need be to drill a small hole in the weights to lighten them up and slow the curve?

[steve25]

I have drilled out weights to change the curve, but it should be done on a drill press with a stop if your not going all the way thru,

If you do not have such then you need a good size number drill set so that you use small size bits to drill completely thru the weight.

These two methods are perfered over sanding.

[steve25]

It’s far better to run very heavy weights and heavy springs to control them and never have to deal with them loosing tension.

[Rocky Rotella]

Originally Posted by 67gtospud

This is all great info! I would assume that heavier weights would also sling out quicker thus causing timing to come in faster. Would it be acceptable if need be to drill a small hole in the weights to lighten them up and slow the curve?

General Motors, in fact, did this for some applications! I have some and will try to snap a picture later.

It might be somewhat difficult to accomplish precisely as factory weights are hardened, but I'm sure it's possible with the proper drill bit and speed. I'm not sure how much on an effect it would have though. That'd probably be best measured using a gram scale and distributor machine.

[padgett]

Just a note but the Delco-Remy 1D service manuals have the curve information by distributor part number.

[67gtospud]

Originally Posted by Rocky Rotella

General Motors, in fact, did this for some applications! I have some and will try to snap a picture later.

It might be somewhat difficult to accomplish precisely as factory weights are hardened, but I'm sure it's possible with the proper drill bit and speed. I'm not sure how much on an effect it would have though. That'd probably be best measured using a gram scale and distributor machine.

I don't plan to modify the weights, just wasn't sure of that was acceptable if it had to be done.

I also would like to verify one more thing; vacuum advance is timing added on top of initial and total, correct?
For example; I'm currently at 16 initial, 32 total. If I have an adjustable vacuum can that adds 10 degrees I want that to be at 42 degrees then right?
I just want to make sure I shouldn't be at 32 total with vacuum advance.

[steve25]

Yes, any amount of degrees added by the vacuum advance is in addition to the mechanical number seen at the balancer.

[Rocky Rotella]

I found two identically-shaped original GM points distributor weights in my collection.

Using a gram scale, total weight of the solid unit comes in a 18 grams while the other comes in at 17.5 grams. It's definitely lighter and with it concentrated on the heavy end, it certainly has an effect on rate. I didn't have a chance to verify its effects on the distributor machine, however.

[67gtospud]

Originally Posted by Rocky Rotella

I found two identically-shaped original GM points distributor weights in my collection.

Using a gram scale, total weight of the solid unit comes in a 18 grams while the other comes in at 17.5 grams. It's definitely lighter and with it concentrated on the heavy end, it certainly has an effect on rate. I didn't have a chance to verify its effects on the distributor machine, however.

I would definitely be curious to see exactly how that would effect the timing curve.

Another question I want to bring up and am not sure if it's timing related is run-on. Once my engine is hot it has a dieseling issue and will sometimes run 5-6 extra cycles. I don't believe my throttle blades are open too far as I can close them all the way and get idle down to 600 rpm if I want and the dieseling persists. I currently have idle around 750-800 rpm though.

[lust4speed]

Originally Posted by 67gtospud

...I also would like to verify one more thing; vacuum advance is timing added on top of initial and total, correct?
For example; I'm currently at 16 initial, 32 total. If I have an adjustable vacuum can that adds 10 degrees I want that to be at 42 degrees then right?
I just want to make sure I shouldn't be at 32 total with vacuum advance.

The most important thing here is that mechanical advance is dialed in correctly and you don't try and use mechanical and vacuum to set advance. Mechanical is the important one and determines power output and the safety of the engine, and vacuum is forgiving and really not that critical. In other words we don't hook up vacuum and see that we are only at 39° and try and add more mechanical to make up for it. Set mechanical where it needs to be and let vacuum advance fall where it will. An incorrect vacuum advance might hurt gas mileage on the road but that's usually it. Incorrect mechanical can destroy the engine.

There are a lot of different vacuum pots and they vary in how much timing they add and how quickly they come in. Most of the time the engine doesn't care much since vacuum works at light throttle settings and things are pretty forgiving when the engine has high vacuum. If you get pinging when rolling in the throttle but not at full throttle, this is when you point the finger at the vacuum advance and make changes.

One last thought on the weights. The stock weights will be smoother working and travel out and back without sticking on the pads. You might end up with one step up on the supplied springs but that's about it. So if your advance curve would be happy with a light and medium spring you might need both medium springs, but the smoothness and repeatability of the stock weights is so much better than stamped weights.

Your throttle blades could still be too far open. Have to take the carb off and turn upside down and see where the blades sit.

[johnta1]

I also would like to verify one more thing; vacuum advance is timing added on top of initial and total, correct?
For example; I'm currently at 16 initial, 32 total. If I have an adjustable vacuum can that adds 10 degrees I want that to be at 42 degrees then right?
I just want to make sure I shouldn't be at 32 total with vacuum advance.

The vacuum advance changes with the amount of vacuum, which varies by RPM and throttle opening. More throttle, less vacuum and vacuum advance. With centrifugal, more RPM, more centrifugal advance.

So more than likely you would never have full centrifugal advance and full vacuum advance.

[67gtospud]

Originally Posted by lust4speed

The most important thing here is that mechanical advance is dialed in correctly and you don't try and use mechanical and vacuum to set advance. Mechanical is the important one and determines power output and the safety of the engine, and vacuum is forgiving and really not that critical. In other words we don't hook up vacuum and see that we are only at 39° and try and add more mechanical to make up for it. Set mechanical where it needs to be and let vacuum advance fall where it will. An incorrect vacuum advance might hurt gas mileage on the road but that's usually it. Incorrect mechanical can destroy the engine.

There are a lot of different vacuum pots and they vary in how much timing they add and how quickly they come in. Most of the time the engine doesn't care much since vacuum works at light throttle settings and things are pretty forgiving when the engine has high vacuum. If you get pinging when rolling in the throttle but not at full throttle, this is when you point the finger at the vacuum advance and make changes.

One last thought on the weights. The stock weights will be smoother working and travel out and back without sticking on the pads. You might end up with one step up on the supplied springs but that's about it. So if your advance curve would be happy with a light and medium spring you might need both medium springs, but the smoothness and repeatability of the stock weights is so much better than stamped weights.

Your throttle blades could still be too far open. Have to take the carb off and turn upside down and see where the blades sit.

I just pulled my carbs off to look to see where the throttle blades are sitting. The secondary carb was definitely open more than the primary carb and I do run straight linkage. I reset them both to equal and will reset the linkage.
Is this open enough though to cause dieseling?

[steve25]

Does stabbing the gas and switching off the ignition just as the rpm starts to drop down make the run condition on worse or better?

[67gtospud]

Originally Posted by steve25

Does stabbing the gas and switching off the ignition just as the rpm starts to drop down make the run condition on worse or better?

Can't say I've tried that. I usually just let the clutch out a little to kill the engine while turning the key off