Mileage Quest 2011!

[cdeal28078]

Woods what is your profession if I may ask? If you are not a shop teacher you missed your calling because you sure can explain things so a normal person can understand them. I get what you are saying about all of this and have always agreed about all of it except running manifold vacuum. Only reason I don't like manifold vacuum is I read a lot about it and how it was better and tried it on a 351w I once had in my F100. I could never get a good idle with it. It hunted all over the place so I swapped it back to ported. I understand how they are both the same once the throttle opens. I will give it a try on my 460 when I get some time as I am all for great throttle response and getting the most out of my engines be it performance or economy.
clint

[cdeal28078]

What about just adjusting the vacuum pod? I always make sure I have one that is adjustable. How do you tell what vacuum the pod is? Is it marked on there somewhere because if I go to the local parts house and tell the kid there I want a vacuum advance pod for a 77 460 with 18inches of vacuum his head is liable to blow up!
clint

[woods]

What about just adjusting the vacuum pod? I always make sure I have one that is adjustable. How do you tell what vacuum the pod is? Is it marked on there somewhere because if I go to the local parts house and tell the kid there I want a vacuum advance pod for a 77 460 with 18inches of vacuum his head is liable to blow up!
clint

Hey Clint...I have a list stored for different cans around here somewhere, I looked a little but did not see it right away, I will keep looking. I used to use it to fish out good vac pods from the junkyard. Anyway, to set your adjustable correctly, it depends on which type of can you have. Some of them only limit the amount that it's allowed to advance and not the hg when the advance starts. If it's the type where you can adjust how much it takes to pull it open, then you need a vacuum pump with a gauge. Give it vacuum until its fully advanced and then take the reading from the pump. If it's too high, get out your allen wrench and make your adjustments until it opens at the amount you want.
Also...here is a graph depicting the difference in ported vacuum and manifold vacuum on a drive. As you can see, no difference aside from when the throttle is closed.
I'll keep looking for the part number list and post it.

[cdeal28078]

Don't trouble yourself looking too hard for it. I'll just start messing with it and see what happens. Also, great graph but you don't have to convince me. I always looked at the ported as just an on off switch for the vacuum and the manifold as having no switch. They are both the same as soon as you hit the throttle.
You might do a lot of people on here some good. I have been saying a long time that there is a lot of HP and torque left on the table when people just stab the dist. in the hole, set it to 6 BTC and call it good. You need to do a timing curve and set the mechanical then the the rest after you set the initial of course.
People on here are getting 6-8 mpg on FE's and are happy with it when I KNOW they can get better fuel mileage if the timing and carbs are tuned better.
clint

[woods]

Yeah, it's just a switch. I can actually rub 15mpg in my 71 4X4 with 35 inch tires, 411 gears and a 428. So yeah, timing helps. I'll post it when I find it anyway, it's good to know when you're poking around a junkyard. I would say try a little less spring tension on it for starters (you already know this I'm sure) that should take less vac to make it operate, but keep in mind, that can also control the amount of advance it see at idle. Try to keep it 20 degrees or under at idle with the can hooked up and fully engaged.

[Ranchero50]

Woods, that graph is pretty cool and I stand corrected. I always 'figured' there was more of a difference at part throttle. Sadly the only engine I have to play with is in my '68 Fairlane and it only comes out once every year or so (to get washed and then rained on before getting put away). The Ranchero is EFI and so is the '93. My '70 has a Cummins between the rails and the '71 a IDI 6.9 Binder.

Jamie

[woods]

I would definitely like to hear or see more about the 70 with the Cummins. I am currently installing an 04 5.9 Cummins in a 63 short wide. More of a hotrod really, but different and I like that. I was thinking that an 11 second pickup that got into the 20's for mileage would be pretty cool.

[Ranchero50]

Not completely off topic but here's the thread under the 'projects' subforum.

http://www.fordification.com/forum/view ... 62#p542162

The whole goal is economy and the ability to haul anything home I can load on it.

Jamie

[SoCalExile]

If the gas prices go farther downhill in the year I'm in Afghanistan, then I'm going to reconsider rebuilding the 400 and find a nice 300 to put in it. It already has the perches.

[fomocoguy]

Well, today I switched the distributor over to full manifold vacuum and set the timing up to 16 degrees btdc at 650 rpm (vacuum line plugged), 4 degrees higher than it was. I went for a run, but it was very windy today and that always screws up my results so I'm not counting it. The last time I did a run on a windy day it hurt me by 2 mpg.

All in all the truck is more responsive and is running great with no detonation yet. I do have one problem though; I can't get it to idle less than about 800 rpm. I backed the idle screw all the way out and it won't go any lower. Any ideas?

[woods]

Make sure the fast idle on your choke is not stopping it from going any lower. Is your vac advance adjustable? If not 800 is not terrible, pump and alt spin a little faster.

[67 428 F250]

Hey Joe !
#1) Did you do your run with the vacuum line plugged?, and if so, why?
#2) Is your run a one way or round trip run? When I do a run, I do a round trip run so I get about the same results even when it is windy.
#3) How can it run great with no detonation?, did you mean to early of detonation?
#4) Your carb is getting extra air from some where. Vacuum leak, or butter flies are not closing all the way.
#5) Did you have this problem before you changed to manifold vac?
#6) You will burn unnecessary fuel idling at 800 RPM.
I really enjoy fine tuning my 428 and getting over 14 MPG. As soon as I recoup from Elocker exspense, I plan on replacing my NP 435 with the NV 4500 over drive.
Will

[390bump]

I can't get it to idle less than about 800 rpm. I backed the idle screw all the way out and it won't go any lower. Any ideas?

See if the carburator throttle plates are closing as much as possible. Like woods said, the choke could be stopping them from closing more... there is usually a screw you can back out on the linkage ( after it goes past the fast idle). This is general carburator stuff so it may not be an exact answer for your setup... Bottom line, too fast an idle means it is getting too much air.

[fomocoguy]

Make sure the fast idle on your choke is not stopping it from going any lower. Is your vac advance adjustable? If not 800 is not terrible, pump and alt spin a little faster.

I have a manual choke so I don't believe it's interfering with anything. I think the advance is adjustable; I'll have to shine a light in the vac port and see. I know 800 isn't incredibly high, but I really liked how it sounded and how smooth it idled at 650 or so.

Hey Joe !
#1) Did you do your run with the vacuum line plugged?, and if so, why?
#2) Is your run a one way or round trip run? When I do a run, I do a round trip run so I get about the same results even when it is windy.
#3) How can it run great with no detonation?, did you mean to early of detonation?
#4) Your carb is getting extra air from some where. Vacuum leak, or butter flies are not closing all the way.
#5) Did you have this problem before you changed to manifold vac?
#6) You will burn unnecessary fuel idling at 800 RPM.
I really enjoy fine tuning my 428 and getting over 14 MPG. As soon as I recoup from Elocker exspense, I plan on replacing my NP 435 with the NV 4500 over drive.
Will

1. No, I timed it with the vacuum line plugged.
2. Round trip, but for whatever reason it makesa pretty big difference in my numbers when it's real windy.
3. I mean no spark knock. You know what I meant
4+5. It idled fine at 650rpm before I did the switch. It still does until I hook up the vacuum line and try to adjust the idle back down.

[woods]

Hey Joe, make sure your vac advance does not have a leak in it.