i have read some post on advancing the distributor off manifold advance rather than the port off the carb and noticed that i lost alot of powerwhy is that, my dist has the stock advance curve
manifold vac advance or port vac
- Thread starter 64 200 ranchero
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Can I ask a stupid question?
Do you have a 60-66 Loadomatic (LOM) distributor or the 67+ vacuum advance distributor?
If it is a LOM, you have to use the carb port. If it is a vacuum advance, the manifold vacuum should be better than carb port vacuum.
Did you pull off the vacuum line from the distributor and cap it when you timed the engine? If you didn't, then the timing is off.
Do you have a 60-66 Loadomatic (LOM) distributor or the 67+ vacuum advance distributor?
If it is a LOM, you have to use the carb port. If it is a vacuum advance, the manifold vacuum should be better than carb port vacuum.
Did you pull off the vacuum line from the distributor and cap it when you timed the engine? If you didn't, then the timing is off.
What Dan said.
Idle speed will be higher on manifold and like need to be lowered with the throttle stop screw.
Once you are off idle manifold and port are almost identical and should perform about the same. I would not connect it to something that has constant vacuum draw like the PCV. Just about any other source should be alright.
And again this is for anything that is not a load o mattic. It works on the 67+ points, Duraspark, & DUI.
Idle speed will be higher on manifold and like need to be lowered with the throttle stop screw.
Once you are off idle manifold and port are almost identical and should perform about the same. I would not connect it to something that has constant vacuum draw like the PCV. Just about any other source should be alright.
And again this is for anything that is not a load o mattic. It works on the 67+ points, Duraspark, & DUI.
Howdy:
All ford distributors of the Falcon era are designed for a ported vacuum source. The combination of initial advance setting and built in distributor advance are the variables that equate to performance and economy. a ported vacuum source will have little or no vacuum advance at idle, but advances as rpms increase- in varing amounts depending on distributor. A manifold vacuum source will give maximum advance at any high vacuum engine condition, such as idle and cruize. So, depending on what distributor, if you use a manifold vacuum source on a ported source distributor, you will be getting too much advance at idle and off-idle, and likely at cruize speeds.
Maniflod vacuum to a stock type distributor may be a part solution tuning carbs and timing on engines with a performance cam and/or an engine with low vacuum.
Also the Holley 1940 is a generic carb designed as a replacement carb for the stock Autolite 1100. It is a poor substitute. It should closely match your engine, trans and vehicle combination. A mismatch can be a real head ache.
More information, as Dan said, would be helpful.
Adios, david
All ford distributors of the Falcon era are designed for a ported vacuum source. The combination of initial advance setting and built in distributor advance are the variables that equate to performance and economy. a ported vacuum source will have little or no vacuum advance at idle, but advances as rpms increase- in varing amounts depending on distributor. A manifold vacuum source will give maximum advance at any high vacuum engine condition, such as idle and cruize. So, depending on what distributor, if you use a manifold vacuum source on a ported source distributor, you will be getting too much advance at idle and off-idle, and likely at cruize speeds.
Maniflod vacuum to a stock type distributor may be a part solution tuning carbs and timing on engines with a performance cam and/or an engine with low vacuum.
Also the Holley 1940 is a generic carb designed as a replacement carb for the stock Autolite 1100. It is a poor substitute. It should closely match your engine, trans and vehicle combination. A mismatch can be a real head ache.
More information, as Dan said, would be helpful.
Adios, david
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The load-a-matic runs off of a combination of manifold and venturi vacuum. The vacuum source directed to the distributor is controlled by the spark control valve (SCV) located on the carburetor. As David mentioned, the manifold vacuum source will have high vacuum at idle and cruise conditions. However, when you step on the gas, the manifold vacuum drops and the vacuum advance portion of the timing is reduced depending on how far the throttle plates are openned. On a Load-a-matic distributor hooked up to manifold vacuum without the SCV, the manifold vac would fall very low and not be able to pull the vacuum diaphram and linkage in the distributor. Therefore the timing would be retarded and the engine would be running only on the Static or initial timing.
The load-a-matic lacks an advance mechanism that is directly tied to rpm's of the motor and distributor. So to advance the timing with increasing rpm's, the Load-o-matic relies on the venturi vacuum. At higher rpm's, more air flow flows through the carb's venturi and this creates a larger vacuum signal with increasing rpm's. The increased venturi vacuum signal is what advances the spark with increasing engine rpm's in the load-a-matic distributor. Without the SCV in the loop and switching / blending the vacuum signal, the load-a-matic is left without a means to increase the timing in relation to the engine rpm, and engine performance will suffer.
Those posts recommending the use of manifold are directed to 1968 and later distributors that have both a vacuum advance mechanism and a centrifugal advance mechanism. In later distributors a simplistic view is that the vacuum advance contributes additional spard advance at idle and part throttle, high vacuum conditions. Centrifugal takes care of advancing the timing as engine rpm increases.
In the Small Six Tech section this post explains the Spark Control Valve
viewtopic.php?f=1&t=18841&start=0
Doug
The load-a-matic lacks an advance mechanism that is directly tied to rpm's of the motor and distributor. So to advance the timing with increasing rpm's, the Load-o-matic relies on the venturi vacuum. At higher rpm's, more air flow flows through the carb's venturi and this creates a larger vacuum signal with increasing rpm's. The increased venturi vacuum signal is what advances the spark with increasing engine rpm's in the load-a-matic distributor. Without the SCV in the loop and switching / blending the vacuum signal, the load-a-matic is left without a means to increase the timing in relation to the engine rpm, and engine performance will suffer.
Those posts recommending the use of manifold are directed to 1968 and later distributors that have both a vacuum advance mechanism and a centrifugal advance mechanism. In later distributors a simplistic view is that the vacuum advance contributes additional spard advance at idle and part throttle, high vacuum conditions. Centrifugal takes care of advancing the timing as engine rpm increases.
In the Small Six Tech section this post explains the Spark Control Valve
viewtopic.php?f=1&t=18841&start=0
Doug