Vacuum source on an Edelbrock carb...
#1
12-09-2005, 11:48 AM
Vacuum source on an Edelbrock carb...
Good morning gentlemen. I have a question on which vacuum source to use on my 460. I just took delivery of an Edelbrock Performer manifold and a 750 cfm Edelbrock carb with manual choke (#1407). My question is...there are two vacuum sources to choose from for vacuum advance: Ported and Full-time. Which should I choose for my engine? Specs are as follows...
Stock 460.
Stock Duraspark ignition.
Stock distributer.
My truck is out of smog.
Thank you for your help.
Jim
Stock 460.
Stock Duraspark ignition.
Stock distributer.
My truck is out of smog.
Thank you for your help.
Jim
#3
12-09-2005, 01:06 PM
Thank you...
Try this:http://www.edelbrock.com/tech/index.html
Thank you for your help. I searched the Edelbrock site but didn't find this page.
Jim
Thank you for your help. I searched the Edelbrock site but didn't find this page.
Jim
#4
12-09-2005, 01:25 PM
Postmaster
Jim: The vacuum source you want for the distributor is ported, which means it is inactive at idle, and gets vacuum once the throttle butterflys open.
If I remember, it is the one on the right, as you are facing the engine.
The other one is manifold vacuum, which has vacuum all the time. This one can be used for various smog valves, and for acuum operated accesories such as air handling. If you don;t need it, just block it off with a plug.
To double check my right and left, check the ports this way, with the engine running at normal temp and idling:
Manifold vacuum will make the manifold nozzle have vacuum at idle.
The ported vacuum inlet will not have vacuum at idle, but will show it when you apply some throttle.
Of course, this assumes the carb is tuned right and the engine is tuned and timed right as well. If the idle speed screw is in further than it should be because you are trying to compensate for some problem, then you may get vacuum at the ported nozzle because the idle screw has opened the butterflys.
Hope this helps.
If I remember, it is the one on the right, as you are facing the engine.
The other one is manifold vacuum, which has vacuum all the time. This one can be used for various smog valves, and for acuum operated accesories such as air handling. If you don;t need it, just block it off with a plug.
To double check my right and left, check the ports this way, with the engine running at normal temp and idling:
Manifold vacuum will make the manifold nozzle have vacuum at idle.
The ported vacuum inlet will not have vacuum at idle, but will show it when you apply some throttle.
Of course, this assumes the carb is tuned right and the engine is tuned and timed right as well. If the idle speed screw is in further than it should be because you are trying to compensate for some problem, then you may get vacuum at the ported nozzle because the idle screw has opened the butterflys.
Hope this helps.
#5
12-09-2005, 01:34 PM
Thank you...
Originally Posted by banjopicker66
Jim: The vacuum source you want for the distributor is ported, which means it is inactive at idle, and gets vacuum once the throttle butterflys open.
If I remember, it is the one on the right, as you are facing the engine.
The other one is manifold vacuum, which has vacuum all the time. This one can be used for various smog valves, and for acuum operated accesories such as air handling. If you don;t need it, just block it off with a plug.
To double check my right and left, check the ports this way, with the engine running at normal temp and idling:
Manifold vacuum will make the manifold nozzle have vacuum at idle.
The ported vacuum inlet will not have vacuum at idle, but will show it when you apply some throttle.
Of course, this assumes the carb is tuned right and the engine is tuned and timed right as well. If the idle speed screw is in further than it should be because you are trying to compensate for some problem, then you may get vacuum at the ported nozzle because the idle screw has opened the butterflys.
Hope this helps.
If I remember, it is the one on the right, as you are facing the engine.
The other one is manifold vacuum, which has vacuum all the time. This one can be used for various smog valves, and for acuum operated accesories such as air handling. If you don;t need it, just block it off with a plug.
To double check my right and left, check the ports this way, with the engine running at normal temp and idling:
Manifold vacuum will make the manifold nozzle have vacuum at idle.
The ported vacuum inlet will not have vacuum at idle, but will show it when you apply some throttle.
Of course, this assumes the carb is tuned right and the engine is tuned and timed right as well. If the idle speed screw is in further than it should be because you are trying to compensate for some problem, then you may get vacuum at the ported nozzle because the idle screw has opened the butterflys.
Hope this helps.
Jim
PS: Just in case I haven't mentioned it recently...I think this site is absolutely awsome. I don't know how I'd get along without it. Thank you gentlemen!