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#3385084 - 05/30/14 05:50 PM Re: Pinging goes away after vacuum adv disc - why? [Re: wag123]
Merkava_4 Offline


Registered: 01/30/07
Posts: 9189
Loc: Clovis, CA
Originally Posted By: wag123
I can also tell everyone from personal experience that IMHO, on a carbureted street driven non-emissions-system-equipped high performance vehicle, you should ALL be using a vacuum advance distributor and you should ALL be using manifold vacuum to control it.


Isn't manifold vacuum full strength vacuum at idle? Back in the day, we'd have the vacuum hose going from the distributor advance diaphragm to the ported vacuum hookup on the carburetor (above the throttle plate) - that way the vacuum would gradually increase as you accelerate off of idle.

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#3385090 - 05/30/14 05:58 PM Re: Pinging goes away after vacuum adv disc - why? [Re: Merkava_4]
wag123 Offline


Registered: 06/14/11
Posts: 549
Loc: Texas
Originally Posted By: Merkava_4
Originally Posted By: wag123
I can also tell everyone from personal experience that IMHO, on a carbureted street driven non-emissions-system-equipped high performance vehicle, you should ALL be using a vacuum advance distributor and you should ALL be using manifold vacuum to control it.


Isn't manifold vacuum full strength vacuum at idle? Back in the day, we'd have the vacuum hose going from the distributor advance diaphragm to the ported vacuum hookup on the carburetor (above the throttle plate) - that way the vacuum would gradually increase as you accelerate off of idle.

No. Vacuum will be at it's maximum when the car is at a low-load steady-state cruising speed.
Go to the links that I left a few posts back and read them.

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#3385324 - 05/30/14 11:08 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
artificialist Offline


Registered: 09/23/07
Posts: 6770
Loc: Florida
When your car was built, I don't know if gasoline had ethanol added to it, but now in many cases it does. Do you know if the fuel used by the rebuilder had ethanol? When ethanol is added, it leans the AFR in engines that don't have O2 sensors. Leaning the AFR can result in knock if ignition timing isn't changed to compensate.

And of course, one of the problems you may be encountering is how the smog devices were configured on the dyno, versus in your car.

Do you have any vacuum leaks? I remember working with a 70s Lincoln, and I noticed many vacuum operated devices. If any of those leaked, you could have an incorrect AFR, and those devices wouldn't be attached to the engine while dyno testing.
_________________________
2010 Lancer Ralliart Sportback

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#3386884 - 06/02/14 10:39 AM Re: Pinging goes away after vacuum adv disc - why? [Re: Merkava_4]
440Magnum Offline


Registered: 02/01/09
Posts: 6265
Loc: Texas
Originally Posted By: Merkava_4


Isn't manifold vacuum full strength vacuum at idle? Back in the day, we'd have the vacuum hose going from the distributor advance diaphragm to the ported vacuum hookup on the carburetor (above the throttle plate) - that way the vacuum would gradually increase as you accelerate off of idle.


Yes, except for "big" cams (with a lot of overlap). Almost every stock factory cam from the 60s-80s will produce max vacuum at idle, buta lot of aftermarket cams won't pull enough vacuum at idle to run power brakes. They have to be spinning ~2000 RPM under light load to hit maximum vacuum. Also when these "big" cams are idling, the vacuum becomes very erratic. The idle speed lopes and surges under the best of conditions and connecting to manifold vacuum can make that even worse, since now you have the advance surging around and feeding back making the engine surge worse.
_________________________
'66 Dodge Polara & '69 Dodge Coronet R/T both 440/727
'08 Ram 1500 4.7/545RFE
'12 Challenger SRT8 392/6-speed
'99 Cherokee 4.0, '11 Grand Cherokee 3.6

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#3387124 - 06/02/14 03:50 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
sasilverbullet Offline


Registered: 08/22/04
Posts: 866
Loc: San Antonio, Tx
Originally Posted By: sasilverbullet
...I will try a couple of things base on ya'lls suggestions:
1. Use my trusty vacuum gauge to see what actually on the dist line.
2. Depending on the results, probably run a line direct from the "timed" port on the carb to the dist and see how that fairs.
3. Depending on how that all works, might try adjusting the vacuum advance if it's adjustable.
4. If all else fails, ditch the vacuum advance entirely.


OP update - I tried pretty much everything everyone suggested except changing the mechanical springs out and the only thing that works is running with the vacuum advance disconnected.

What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??

So I'm just running the mechanical advance - it doesn't ping and seems to be running fine.

I'll leave it like this for a while and see how things go.
_________________________
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04 Nissan Titan - Amsoil 5W-30 XL

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#3387146 - 06/02/14 04:33 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
wag123 Offline


Registered: 06/14/11
Posts: 549
Loc: Texas
Originally Posted By: sasilverbullet
Originally Posted By: sasilverbullet
...I will try a couple of things base on ya'lls suggestions:
1. Use my trusty vacuum gauge to see what actually on the dist line.
2. Depending on the results, probably run a line direct from the "timed" port on the carb to the dist and see how that fairs.
3. Depending on how that all works, might try adjusting the vacuum advance if it's adjustable.
4. If all else fails, ditch the vacuum advance entirely.


OP update - I tried pretty much everything everyone suggested except changing the mechanical springs out and the only thing that works is running with the vacuum advance disconnected.

What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??

So I'm just running the mechanical advance - it doesn't ping and seems to be running fine.

I'll leave it like this for a while and see how things go.

I suspect that the idle throttle opening may be too far open to close off the port vacuum holes in the carburetor throat.

BTW: Going back to what I said about using manifold vs port vacuum for the vacuum advance, I found this statement in the Edelbrock 1406 owners manual...
Long Duration Camshaft
If the engine has a fairly radical camshaft it may require an excessive amount of throttle
opening for idle and/or have low idle vacuum levels. Either condition can lead to poor levels of adjustability and erratic idles.
Another fix for the above condition is to run as much spark advance as possible at idle. If the distributor is fitted with a vacuum advance unit, connect it directly to manifold vacuum. If you are not able to employ vacuum advance for some reason, then the mechanical curve should have a low limit, which will allow you to use plenty of initial spark advance.

The last sentence sounds like what the dyno tuner did. You will never know unless you check it with a timing light.
If the car runs good with the vacuum advance disconnected, then run it that way and don't worry about it. But, if you could get the vacuum advance working so you could add another 12 to 15 degrees of advance at low load light throttle settings, you could experience a fairly significant gain in cruising fuel mileage.

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#3387807 - 06/03/14 11:40 AM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
440Magnum Offline


Registered: 02/01/09
Posts: 6265
Loc: Texas
Originally Posted By: sasilverbullet

What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??

So I'm just running the mechanical advance - it doesn't ping and seems to be running fine.

I'll leave it like this for a while and see how things go.


This is a Lima Ford engine right? Takes a lot of air to idle one of those ;-) I imagine that the Edelbrock doesn't have enough air flow to idle the engine without the throttle blades being cracked open far enough to expose the transfer slots and ports to manifold vacuum. Common problem on big-displacement engines, actually, my 440s are the same way. The ideal solution is to set the idle speed where you want it, remove the carb, flip it over, and see where the throttle blades are with the throttle against the idle stop. If they're exposing the ports and slots, drill a small air bleed hole in each throttle blade near the idle fuel inlet side of the blade. That lets you close the blades and cover the ports while still maintaining enough air flow for idle. Factory big-block carbs usually already have holes in the throttle blades.

But obviously doing this is not easily reversible- proceed with caution and start small!
_________________________
'66 Dodge Polara & '69 Dodge Coronet R/T both 440/727
'08 Ram 1500 4.7/545RFE
'12 Challenger SRT8 392/6-speed
'99 Cherokee 4.0, '11 Grand Cherokee 3.6

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#3387906 - 06/03/14 02:18 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
Gokhan Offline


Registered: 12/29/10
Posts: 1547
Loc: Los Angeles, California
Originally Posted By: sasilverbullet
This one's stumping me - on my newly overhauled 460 in my 70 Lincoln MK III, it pings on acceleration. If I disconnect the vacuum advance it doesn't ping.

Why?

??? ??? ???

Of course, engines ping when you advance the ignition timing too much.

The optimal timing is such that the engine pings very lightly when the transmission gently shifts to overdrive on a slight upward slope. If that's the case, you have the optimal compromise between fuel economy + horse power (more advanced ignition timing the better for that purpose) and engine pinging + emissions (more retarded timing the better for that purpose). Therefore, do the test I explained and adjust the ignition timing for light pinging under those conditions.
_________________________
1985 Toyota Corolla LE, 4A-LC engine, ~ 257,000 M
Toyota (by ExxonMobil) SN/GF-5 0W-20 Synthetic
Toyota 90915-YZZF2 filter, 90430-12031 drain gasket

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#3388702 - 06/04/14 01:21 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
SteveSRT8 Offline


Registered: 10/10/08
Posts: 14785
Loc: Sunny Florida
Originally Posted By: sasilverbullet

OP update - I tried pretty much everything everyone suggested except changing the mechanical springs out and the only thing that works is running with the vacuum advance disconnected.

What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??

So I'm just running the mechanical advance - it doesn't ping and seems to be running fine.

I'll leave it like this for a while and see how things go.


As stated by many here the advance can be set by simply adjusting to the pinging threshold. No ping at all means you need more advance!


Use the gas you want and the engine needs to be HOT. With the timing advanced the engine will be much more responsive and fun, retarded timing really takes your throttle response with it...


Edited by SteveSRT8 (06/04/14 01:21 PM)
_________________________
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#3389004 - 06/04/14 06:55 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
flanso Offline


Registered: 12/26/06
Posts: 319
Loc: Houston, TX
Originally Posted By: sasilverbullet
[quote=sasilverbullet]
What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??


The spark port in an emission controlled carburetor is slightly further above the the fully closed throttle valve than in a non-emission carb. The higher spark port delays the vacuum signal to the distributor. That delay reduces hydrocarbons but may compromise drivability. If you're happy with drivability, go with the vacuum advance disconnected. If you would like the vacuum connected, retard your initial timing until it barely pings. Then adjust the stop for the mechanical advance, under the breaker plate, so you get the same total advance as you did before before you retarded the timing.

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#3389106 - 06/04/14 08:47 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
1 FMF Offline


Registered: 08/12/02
Posts: 1506
Loc: CT
Originally Posted By: sasilverbullet
[quote=sasilverbullet]

What I don't understand is why the "timed" port on my Edelbrock 1406 doesn't look any different on the vacuum gauge compared to the other port on the carb and straight from the manifold??


because it's a 460 and you have a 600 cfm carb if i read the correct posts by you in a previous thread. you most likely have the throttle blades open too far to allow enough air in for idle and you've exposed the ported vacuum port. so at idle for you your delayed ported vacuum source is basically the same as full manifold vacuum. if you pull the carb and look at where you have the throttle blades set for idle via the idle stop screw, i'll bet the ported vacuum hole is exposed below the throttle blade.

also, what i wrote previously when i said ported I meant venturi vacuum.

here is [another] good read on the subject:
http://www.corvetteactioncenter.com/foru...um-advance.html

did you ever mention what you had done to the motor, what heads you are running and what camshaft ? I only found edelbrock 2166 dual plane intake and 1406 carb.
are you running the oem distributor and coil, what are you running for an ignition?
and what intake manifold vacuum reading are you getting at 800 rpm and 2000 rpm in neutral?
i don't know what's available these days for distributor based ignitions, but if it were me i would be looking for a programmable box that runs with a MAP sensor and lets you program a spark advance table to your hearts content with a laptop. MSD ought to have something like that at least. It all comes down to what your ignition timing is based on rpm and engine load where engine load is based on intake manifold vacuum. google spark advance maps or ignition timing maps if you are not familiar, that's what you are creating with your mechanical advance springs and vacuum advance can in the distributor. if you know your distributor mechanical advance curve and how the vacuum advance works, then engine rpm and an intake manifold vacuum gauge will give you the data so you can populate your [analog] spark table and see what's going on with what you have now.

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#3389682 - 06/05/14 11:46 AM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
sasilverbullet Offline


Registered: 08/22/04
Posts: 866
Loc: San Antonio, Tx
I just ordered a adjustable vacuum advance and some springs for the mechanical advance. Stay tuned...
_________________________
14 Honda Civic 4dr EX-L - Honda Synthetic 0W-20 for now
14 Honda Accord 4dr EX-L - Honda Synthetic 0W-20 for now
04 Nissan Titan - Amsoil 5W-30 XL

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#3389751 - 06/05/14 12:50 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
Gokhan Offline


Registered: 12/29/10
Posts: 1547
Loc: Los Angeles, California
Originally Posted By: sasilverbullet
I just ordered a adjustable vacuum advance and some springs for the mechanical advance. Stay tuned...

Springs for the mechanical advance don't go bad. However, what goes bad is the governor shaft, which tends to weld onto the distributor shaft because the grease used is usually of poor quality and dries over time. If that's the case, the only workaround is to replace the distributor altogether, as you can't replace the shaft.

I recently rebuilt my distributor and generously lubricated the mechanical-advance shaft with Valvoline 100%-synthetic grease with moly. The OEM distributor wasn't even that old (about nine years) but there was already some lubrication loss in the shaft and there were some small wear scars.

If your mechanical advance is shot due to lubrication loss and heavy wear, I guess you could try to make up for it by tuning your adjustable vacuum advance. The distributors are really expensive and you may not even be able to find one.

I wonder why they wouldn't make some electronic aftermarket distributors. They would be far more reliable and cheaper than the early-20th-century mechanical-distributor technology.
_________________________
1985 Toyota Corolla LE, 4A-LC engine, ~ 257,000 M
Toyota (by ExxonMobil) SN/GF-5 0W-20 Synthetic
Toyota 90915-YZZF2 filter, 90430-12031 drain gasket

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#3389821 - 06/05/14 02:22 PM Re: Pinging goes away after vacuum adv disc - why? [Re: sasilverbullet]
wag123 Offline


Registered: 06/14/11
Posts: 549
Loc: Texas
Originally Posted By: sasilverbullet
I just ordered a adjustable vacuum advance and some springs for the mechanical advance. Stay tuned...

Now, you need to bum an adjustable advance timing light from someone. If you don't know anybody that has one, buy one for $55 or so off Amazon. You don't need to buy an expensive one because you won't be getting very much use out of it. Make sure you buy one with the adjustable advance, don't cheap out! You don't need one with a digital adjuster, the dial type is fine, that is what I have and I actually prefer the dial.
http://www.amazon.com/Actron-CP7528-Advance-Timing-Light/dp/B000BSWEHS/


Edited by wag123 (06/05/14 02:24 PM)

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#3389904 - 06/05/14 03:54 PM Re: Pinging goes away after vacuum adv disc - why? [Re: wag123]
Gokhan Offline


Registered: 12/29/10
Posts: 1547
Loc: Los Angeles, California
Originally Posted By: wag123
Originally Posted By: sasilverbullet
I just ordered a adjustable vacuum advance and some springs for the mechanical advance. Stay tuned...

Now, you need to bum an adjustable advance timing light from someone. If you don't know anybody that has one, buy one for $55 or so off Amazon. You don't need to buy an expensive one because you won't be getting very much use out of it. Make sure you buy one with the adjustable advance, don't cheap out! You don't need one with a digital adjuster, the dial type is fine, that is what I have and I actually prefer the dial.
http://www.amazon.com/Actron-CP7528-Advance-Timing-Light/dp/B000BSWEHS/

I wouldn't go analog, as the digital ones come with a tachometer and are far easier to use and more accurate.

I have had an Innova for many years and the light bulb still hasn't burned out. I had bought a cheap $30 one (likely the Actron brand) and the bulb burned out after a few minutes of use. I would definitely recommend the Innova. The one I have is the following one and it's only $80. I had paid about $100 about 15 years ago:

http://www.amazon.com/INNOVA-3568-Digital-Timing-Light/dp/B000EVYGV4/
_________________________
1985 Toyota Corolla LE, 4A-LC engine, ~ 257,000 M
Toyota (by ExxonMobil) SN/GF-5 0W-20 Synthetic
Toyota 90915-YZZF2 filter, 90430-12031 drain gasket

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