Vacuum advance

Engine, ignition, fuel, cooling, exhaust

Moderators: Ranchero50, DuckRyder

whiteblur
New Member
New Member
Posts: 189
Joined: Sun Mar 13, 2011 7:26 pm

Re: Vacuum advance

Post by whiteblur »

forrestbump wrote:My guess is your vacuum advance line is connected to the ported vacuum tube, I've followed Woods' advice and connected mine to the direct port, readjusted my carb and admit it's running much better.
mine is connected to the vacuum advance line and yours is to the direct port :? not understanding
User avatar
forrestbump
100% FORDified!
100% FORDified!
Posts: 2140
Joined: Tue Aug 10, 2010 12:23 am
Location: California, Phelan

Re: Vacuum advance

Post by forrestbump »

There are usually two vacuum ports (metal tubes) in the front of carbs. The higher port (tube) is called a timed port as it is affected by butterfly movement. The lower port (tube) is a direct source of vacuum and is NOT affected by butterfly movement.

Most carb suppliers recommend using the timed port, but after reading Woods' (he's a very knowledgeable member here) posts in the "Mileage Quest" thread found in General Discussion, I've changed my thinking and now recommend using the direct port location as the proper source for vacuum advance canisters.
1970, 2WD, F-250, C/S, Dual Tanks, 390 FE (of course), C6, Power Steering, Power Disc Brakes, Dana 60 3.73, Sky View Blue, Ranger XLT

1970, 2WD, F-250, C/S, A/C, Dual Tanks, 390 FE (again, of course), C6, Power Steering, Power Disc Brakes, Dana 60 3.73, Wimbledon White & Sky View Blue, Ranger (almost twin brothers!)

"One of the greatest discoveries a man makes, one of his great surprises, is to find he can do what he was afraid he couldn't do" - Henry Ford

Larry
tmcalavy
Blue Oval Fan
Blue Oval Fan
Posts: 575
Joined: Fri Dec 31, 2010 4:15 pm

Re: Vacuum advance

Post by tmcalavy »

I think a picture is worth a thousand words in this situation...don't have an I-6 anymore, so can someone post one showing him the vacuum line routing? He is unfamiliar with our/your terminology.
User avatar
woods
100% FORDified!
100% FORDified!
Posts: 2121
Joined: Sat Apr 02, 2011 10:34 am
Location: Washington

Re: Vacuum advance

Post by woods »

It may be a bad vac can like mentioned above. It may also be pulling in too much timing OR if the plate your points sit on is worn out, the vac advance can pull it at an odd angle which can change your point gap. Fix the vac leak and fix whatever is going on with your distributor. Running "fine" is really up to personal interpretation. With a vac leak and no vac advance...I can tell you without even driving it, that I personally would not think it ran fine. In other words, if you think it runs good now, you will be amazed at how it can run when everything is correct.
Whateverman
Blue Oval Guru
Blue Oval Guru
Posts: 1257
Joined: Sat Jan 08, 2011 6:45 pm
Location: Comox Valley B.C. Canada

Re: Vacuum advance

Post by Whateverman »

it may run "fine" idling in the driveway and revving it up with the vac advance off, but it'll end up pinging and knocking its way up the road ,especially if you run into any hills- not to mention backfiring ,stumbling and stalling
- still got my first first car 20+yrs later : 69 f100 sorta kinda pretending its a Mercury M100 w/a 70 f350 sport custom cab (factory buckets) 67 grille with 69 ranger cooneyes 68 merc box and hood,some supercool fiberglass fenders i scored way back when, 76 f150 disc brake frontend..currently running a 90 5.0HO 4bbl/c4 auto & 3.50 posi...originally a 360/c6 f100 Ranger with dealer added towpack (incl. kelsey hays trailer brake),boxside toolbox,behind the seat stowage & belly tank...only original parts left on 'er are the frame,rear end,rear springs,and rear bumper...
fordman
100% FORDified!
100% FORDified!
Posts: 22329
Joined: Sun Aug 28, 2005 8:17 pm
Location: Kansas, Ottawa
Contact:

Re: Vacuum advance

Post by fordman »

there is some thermactor type of vaccum routing on this page. that may help. http://www.fordification.com/tech/schematics_e.htm
whiteblur
New Member
New Member
Posts: 189
Joined: Sun Mar 13, 2011 7:26 pm

Re: Vacuum advance

Post by whiteblur »

i checked the vacuum can and it all seems to be good. I took it for a drive around the neighbor hood with the other port open and the vacuum advanced hooked up and it stumbles and the exhuast pops and when you slow down or push in the clutch if you dont give it gas, it'll die
User avatar
woods
100% FORDified!
100% FORDified!
Posts: 2121
Joined: Sat Apr 02, 2011 10:34 am
Location: Washington

Re: Vacuum advance

Post by woods »

First...no vacuum port should be uncapped.

Now take your distributor cap off and slide the plate your points sit on toward the way the canister pulls it. Is it loose? Does your point Gap change from one position to the nest even though they are on the high spot of the cam?
tmcalavy
Blue Oval Fan
Blue Oval Fan
Posts: 575
Joined: Fri Dec 31, 2010 4:15 pm

Re: Vacuum advance

Post by tmcalavy »

Unless I missed something...wish we knew which carb you have so someone can tell you how may vacuum hookups you have and which ones should be capped and which one connects to the distributor. Until then, who can say?
whiteblur
New Member
New Member
Posts: 189
Joined: Sun Mar 13, 2011 7:26 pm

Re: Vacuum advance

Post by whiteblur »

Carter yf manual choke
tmcalavy
Blue Oval Fan
Blue Oval Fan
Posts: 575
Joined: Fri Dec 31, 2010 4:15 pm

Re: Vacuum advance

Post by tmcalavy »

Try this on for size:
http://oldcarmanualproject.com/manuals/ ... /index.htm
It's been too many years for me to remember the exact YF vacuum routing.
If the link above doesn't help do a Google search for Carter YF manual choke vacuum diagram and see what you get.
You may have a PCV vacuum connection on the manifold under the carb, and for sure one vac port on the carb that goes to your distributor...but can't remember where you attach the power-brake booster vac line on your setup. Hang in there, you're getting closer.
happycamper
New Member
New Member
Posts: 131
Joined: Mon Feb 15, 2010 2:04 am
Location: Los Angeles, California

Re: Vacuum advance

Post by happycamper »

vacuum advance is supposed to go to a "timed" vacuum port; not a full-time/full manifold vacuum port. If it is hooked to full manifold vacuum, you will be running "advanced" all the time. Just went through this with Holley tech support. My :2cents:
1968 F-250 Camper Special Ranger 16769 Original miles :D
User avatar
woods
100% FORDified!
100% FORDified!
Posts: 2121
Joined: Sat Apr 02, 2011 10:34 am
Location: Washington

Re: Vacuum advance

Post by woods »

Holley tech is wrong (just so you know). I don't want to go through all this over again. Please read this.
http://www.fordification.com/forum/view ... &start=120
User avatar
Fo-Mo-Co
Preferred User
Preferred User
Posts: 348
Joined: Wed Jan 05, 2011 9:35 am
Location: Indiana

Re: Vacuum advance

Post by Fo-Mo-Co »

woods wrote:Holley tech is wrong (just so you know). I don't want to go through all this over again. Please read this.
http://www.fordification.com/forum/view ... &start=120
I second this. I won't go into all the BS I have gon through but Woods is correct Holley is wrong.
"We don't want tradition. We want to live in the present and the only history that is worth a tinker's dam is the history we make today."

Henry Ford
tmcalavy
Blue Oval Fan
Blue Oval Fan
Posts: 575
Joined: Fri Dec 31, 2010 4:15 pm

Re: Vacuum advance

Post by tmcalavy »

I followed woods' link to the other thread and got caught up there with my reading...went out after work today and hooked my dist. up to manifold vacuum on the rear of the 360 in my 69 F250...there's a splitter there. Also plugged the port on the carb that I was using, and really like the engine response now. Like he says, it wakes your engine up. I'll know in a week or so if it makes a difference in mpg...I'm getting 12.7 in town driving right now.
Post Reply