Video won't upload will try later. basically when I plugged vac back in nothing changed at all.

i set idle to 15 (15 mark on my damper to zero mark on my timing tab). Revved till it stopped moving. stopped at around 34 ish btdc. those are my spring settings.
let it idle again. changed timing gun to 32 and revved her up to get tdc on damper to zero on timing pointer (moved counter clockwise on dizzy maybe 1.5" inches.). Never had my dizzy that far turned so advanced in my opinion (not crazy just not that much). Plugged in vacuum and nothing changed at all. Went back to idle for me tdc on damper to 8 degrees on timing tab. brought the dizzy a bit closer to normal. Also I used to idle around 550 with old carb. I'm idling at around 650-700 now. I haven't tuned carb at all, just fyi.

 

I lost the bubble on your thought. So your total maximum mechanical advance is 32 degrees BTDC, and initial is now 8 degrees? Don't worry about initial. Get your max mechanical up to 34-36. At what RPM was max advance maxed out? The springs only affect the RPM at which this happens, not the total advance (by your numbers, either 19 or 24 degrees), which is baked into the distributor.

Plugging the vac advance can into the ported vacuum (no vacuum at idle) is not advised (by me at least), but will also give you no change at idle.

Did you plug the vac advance can into manifold vacuum, and still get no change? Your vac advance can may be toast. Do you have a hand-held vacuum pump to test it with (it can also be used to test vacuum). You can test that the carb port has manifold vacuum with your finger.

 

the port I have it on is the carb port up front (just like where it was with old carb). When you say try the manifold vac you are talking about the one where my headlights are plugged into. never seen that but I see what you mean by 'test it out'

 

These two items will save you a bunch of grief.

Mity-Vac MV8510 (they make cheaper plastic ones, too)
Lisle 20300

I don't know which port to use on a Holley, but I'm sure the internet does! Knowing what vacuum your car is drawing (and seeing it in real-time) is very helpful for debugging.

 

i have one. I'll try it tomorrow. thanks. Will give it another shot and see what I get.

 

I'm still alive. I'll try tomorrow. thanks

 

first it need to be determined is ported or manifold vacuum is being used so everyone is on the same page. headlight port is manifold not ported or your lights wouldnt come up or down at idle... Someone suggested ported earlier and many suggested manifold vaucuum. I also suggested to not focus on initial, only total with the vac disconnected at 3500rpm which should be set to between 34 and 36. (I assume 36 with stock heads as I thats what I read they prefer) once this is done, further distributor troubleshooting might be needed if it does not idle right when the vac is reconnected.

 

ported (never had it connected to manifold on original) no change when connecting vac again (may be an issue with dizzy. but why) initial is at 10btdc at idle and at tdc at 3500 rpm with vac unplugged. like i said once it's connected up again zero difference. remember new carb with stock settings. got it going and can drive it yet it feels like crap and rough idle. secondaries are def not opening up (you would def feel it open before all this started on the old quad) by the way factory sticker on it says 12btdc at 700rpm idle. my idle is about 650-700 if i remember right. i'm going to go recheck all the plugs. I did notice the sticker also said .045 gap and i gapped at .040 but def shouldn't make a difference like that.

 

trying to plug vac advance to manifold vac later tonight just to see if there's a change.

 

I don't understand how you can be getting 0 degrees of advance at 3500 RPM, after having 10 degrees BTDC at idle. Is that a typo, and you had 36 degrees dialed into your timing light?

 

at 3600rpm at 10degrees like I had at idle. not zero. my bad.

 

Can you take a picture of the inside of your distributor? All I can think are that your weights are installed backwards, or there is some other mechanical issue (stuck all the way open with no springs, or something).

That could also explain why your vacuum advance isn't doing anything. Perhaps your can works, but your distributor is welded to a fixed setting.

 

uploading video standby.

 

FORGOT TO MENTION IN VIDEO: WITH NO VAC CONNECTED 3600RPM ZERO TIMING MARK ON DAMPER IS ON 8 DEGREES AFTER tdc meaning the 8 mark on the bottom portion of my tab.

so with vac at 3600rpm my zero mark on damper is on 8 degrees btdc (top number 8 on my tab) and 8 degrees AFTER tdc with no vac.

 

I searched for a photo to demonstrate what I meant by the "inside of your distributor" (the weights and springs underneath your distributor cap), and I got this, relevant thread.

https://www.corvetteforum.com/forums...e-problem.html

 

I've had it opened before and cleaned it up. everything seems to be fine there all parts moving springs seem to be in good shape albeit a bit of rust. did you see the video and my comments afterwards about vac off?

 

You need to grow a third arm, or get a helper.

I still have no idea what you are doing. I'm assuming you have a timing tape on your harmonic balancer. Can you take a clear picture? I can't see any numbers or marks in your video. The 36 you are entering into your timing light is advance. If you punch in 36 degrees, and read Zero on your timing marks, you have 36 degrees of advance, which is what you should have at about 3000 RPM, vac advance disconnected, all-in mechanical on your distributor.

The one time I thought you called out a logical reading was when, at idle, you had 30 degrees total advance (initial plus vacuum, with hopefully zero mechanical advance). This is close to what I run, so that seems valid. You then stated that at 3600 RPM, you had 36 (advance on the timing light), plus another 8 on the timing tape, for a total of 44. It was unclear if that was with or without vacuum advance. You want to make sure your total mechanical is not more than 36, or you are likely to have pinging and wreck your engine.

At least it seems that your dist and vacuum advance are working correctly.

However you get the numbers (and it is probably easier to use the tape than the timing light's advance, but certainly not both or you will continue to confuse your video viewers), you should be able to write a chart like this (example numbers only, based on my measured 21 degrees of total mechanical advance for my HEI distributor, yours may be very different):

RPM Mech Advance
700 15 (initial)
900 15
1200 18 (start of mechanical advance)
...
2500 32
2800 36 (all-in)
3000 36
3600 36

You can then do the difference at idle to determine your total vacuum advance.

 

After watching the video, thinking on it, and reading this a few times, I think that you have 16 degrees of advance cooked into your vac advance (10-12 is recommended).

With the 36 degrees of advance built into your timing light, you are at 28 degrees total mechanical timing at 3600 RPM (36 - 8).

Maybe. Clear photos would help!

 

In the video you still seem to have some issue using the timing light. Your number from the crankshaft VS the number you Input to the light is what is throwing everybody off here.

If you put a 36 into the timing light, then rev the engine to 3500rpm, and see 8* Of timing, it means you have 36 + 8 = 44* total timing. If this is with vac advance disconnected it means the engine will ping and become damaged as you approach 80KPA or near wide open throttle.

The correct way to do these timing tests, is simple but explicit.
You should Perform the test MULTIPLE ways. I am going to give you the advanced topic discussion to clear and agree on the situation.

1. With vac adv disconnected. Timing light set to 0*. Measure at idle:
A. Idle: 8* or 10* or 15* is fine read from the crankshaft. While the timing light reads 0*.
B. 3500RPM: The timing light still set to 0*, now the crank shall read 32 to 35 maybe 36.
You take your 3500rpm measurement, subtract the idle, and that is the total mechanical advance.

2. With vac advance disconnected. Timing light set to the number you got from above for idle, lets say 8* was obtained. So now timing light is set to 8*.
Idle: Should show 0* on the crankshaft.
Next, set the timing light to the number you obtained from B. above, lets say you got 36. So timing light says 36, 3500RPM crankshaft shall say ZERO 0*.

This confirms your mech advance and idle timing is correct, TWO ways.

3. Now, flip the inductive clamp on the plug wire, since Some timing lights are directional. They may have an arrow on the clamp (yours should). IF there is no arrow, you need to flip the clamp and determine which way is correct.
If there IS an arrow, I still like to flip it just to make sure the timing numbers "dont make sense" but this is kind of advanced so if you see an arrow and follow the arrow, then it should be fine.

Now, you can check the vacuum advance. Here is the deal with vac advance, idle, cruise, etc..
1. Vac advance will not apply during cranking. No matter where it is sourced. So your engine will not start easier or whatever when it is connected to ported or not.
2. The OEM Manufacturers recommend ported vacuum for vacuum advance. This is because 30 to 35* Of timing at idle can beat the rod bearings over time. It will create high cylinder peak pressure while the engine is rotating slowly and may cause engine damage over time. The only reason your engine and similar engines (old small blocks) seem to get away with it is because they typically have a low compression and high tolerance for timing due to inefficient combustion chamber design from the 70's 80's (or 60's).
This leads to a few "IF / AND / OR" situations. IF the engine has higher compression and been modified somewhat, the additional timing is more unwelcome.
IF the engine is very tired and old, and has 100,000+ Miles or so, then the extra timing is probably OKAY.
IF the engine is fresh, higher compression, AND it has a large camshaft with overlap to bleed cylinder pressure, and still has the ancient SBC combustion chamber design (Old heads) then the extra timing is probably OKAY.
You really need to be a great diagnostician and mechanic OR have a very old tired engine from the 50-80's before I can recommend a full time manifold vacuum instead of ported. Old school people love using full time manifold advance because it gives the engine an extra kick, an edge, better response etc... But none of them are using a cylinder pressure monitoring tool to understand what sort of peak pressure can develop during the slowly rotating motion of the engine. Imagine the cylinder pressure peaking out before the piston can reach top dead center- it will try to rotate the engine backwards but cannot due to the internal energy (kinetic and momentum energy) Of the rotating assembly. These opposing forces squeeze the rod bearing, ruin the oil film, cause rod bearing damage over time, if they are great enough.

 

Here's a simple rule - Use the adjustment on the light to get the timing mark to be at 0* OR leave the light set to 0* and read degrees from the timing tab. Never mix both methods.

Do this:
1. Disconnect the vacuum advance and plug it.
2. Hold the rpm at 3500rpm and adjust the light until the timing mark is at 0*. Take the reading on the timing light.
3. Drop it back to idle. Adjust the timing light until the timing mark is at 0*. Take the reading on the timing light.
4. Plug in the vacuum advance. Adjust the timing light until the timing mark is at 0*. Take the reading on the timing light.

Tell us what the readings from steps 2, 3 and 4 are. If they make sense and the distributor appears to be working correctly then keep going.

To set the correct mechanical advance:
5. Disconnect the vacuum advance and plug it.
6. Hold the rpm at 3500rpm.
7. Set the timing light to 36*.
8. Move the distributor until the timing mark is showing 0*.
9. Lock the distributor back in place.
10. Re-do the measurements in steps 2-4 and record those values.