Ported vacuum
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Senior User
Joined: Dec 2002
Posts: 373
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From: Wallaceburg On.
Ported vacuum
I am going to be hooking up the vacuum to the distributor and EGR valve on ny 77 f250 351m. I have no other vacuum lines on this truck(other than power brake booster). Firstly; is there any difference from one vacuum source to another on a 2150?
Does it matter which soarce I hook the vacuum advance to?
Secondly is there any advantage to keeping the EGR valve operable?
Thanks in Advance
Greg C
Does it matter which soarce I hook the vacuum advance to?
Secondly is there any advantage to keeping the EGR valve operable?
Thanks in Advance
Greg C
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Most vacuum ports on the 2150 are ported vacuum (mainly under the choke housing and next to the drivers side idle mixture screw). There is a lip on the back for the choke pulloff; that is manifold vacuum. As for the vacuum advance, that is debatable - both setups exist. I personally would try it with ported vacuum first. It depends on your specific timing curve and where your base timing is at. If you know how it came originally, then do that.
As for EGR, you need to keep it. The carb is jetted and distributor is curved accordingly. If you remove it, you will get pinging, and will need to definitely recurve the dist. with an adjustable vacuum advance and possible rejet the carb. You can definitely remove it, you'll just have to make the adjustments I mentioned. I don't run EGR on any of my vehicles, simply because the EGR valve went out, and it was cheaper\easier to make those adjustments then put on a new valve.
As for EGR, you need to keep it. The carb is jetted and distributor is curved accordingly. If you remove it, you will get pinging, and will need to definitely recurve the dist. with an adjustable vacuum advance and possible rejet the carb. You can definitely remove it, you'll just have to make the adjustments I mentioned. I don't run EGR on any of my vehicles, simply because the EGR valve went out, and it was cheaper\easier to make those adjustments then put on a new valve.
