I have been using one for a little while now and am curious as to what some other people are getting for readings during acceleration, cruise at various speeds, etc.

 

Are you using one that reads in inches or mm of hg like a manifold pressure gauge, or psi, like a turbo boost gauge?

 

mine reads in inches

 

I have used a vacuum gauge with a Air/Fuel Ratio gauge to maximize my mileage but since I just bought my Ranger I dont have any baseline numbers yet.

 

i would be interested in comparing numbers. granted I live 5000 feet above sea level. but my 88 pulls 17" at idle (not uncommon around here) cruising in 4th at 55 it sits at 10", and at 65 in 5th it pulls 7". if i wind it up to 75 it only pulls around 4". I'm worried that by then im tapping into the acceleration circuit. making me waste even more fuel.

 

Did the 88 not come with factory EFI? I thought that by then all Ford light duty engines were bank-firing MAP-controlled EFI. Anyway, if it is carb'd, it it high-altitude calibrated emissions? If not, it may be opening up the power valve at four inches and wasting fuel.

Im at 6000ft MSL, but had EFI on everything starting with the '88 Ranger.

 

yeah, its efi, but even efi has a "power enrichment circuit" similar to a power valve, it goes into open loop and feeds a specified mixture instead of listening to the o2 sensor. I know it does it with your foot on the floor, but i'm not sure where it would kick in as far as vacuum goes.

 

So, enrichment it may be triggered by manifold pressure (aka vacuum) or throttle position. Both are sensor inputs to the PCM. We just dont know which one.

 

vacuum gauge- old school knowledge- now days- nobody understands-
all want computer output and digital figures

simply put-
vacuum gauge on any intake manifold fitting will register vacuum-
push the pedal down- the vacuum goes down
steady pedal, engine at optimum running load, cruising, ie: engine not under load- high vacuum- very hard to achieve a vacuum reading that is around what is ideal- 90% of them behind the wheel have no idea what vacuum readings mean, nor care if a vacuum gauge does anything but a needle bounce

Old School- anyone worth their salt knows what a vacuum gauge means- but bangs his head on cement when trying to put the words where the newbees can grasp a meaning--- turely a lost art- anyone who cares could learn a lot talking with the old timers about what true vacuum is- but then again- those same ones would just not hear- they are wiser and not to be taken in by old foggies

 

did you just call me old? or vice-versa?

 

[quote=muscletruck7379;13270142]did you just call me old? or vice-versa?[/quote

does it have any bearing

engine at cruise, under no load, has it's highest intake +vacuum only if and when the engine is operating at optimum level- achieved only in these later years when manufacturers found out the buyer was more concerned with mileage over power- vacuum gauge will tell any driver where and how better fuel economy can be found- very few care to see it

 

Regarding the original question.........1983 F250 with a basically stock 351W, 2150 carb, 4-speed manual, 3.54 axle, at sea level I have -

17.5" @ idle.
16-17"" @ 55mph cruising, flat road - 2180 rpm.
10" @ 55mph up moderate hills, avoiding pushing it hard.
Below 8", the power valve kicks in & it pulls strong, but mileage takes a dive.

 

I am actually in the process of installing a vac guage today in my 81 F150 2wd with a 300... like going to drill a hole this afternoon.

When you guys run the gauge to the engine, do u use a hard line, like brake line, and small rubber lines at the ends for flex, or do you just run rubber line the entire way?

 

I am actually in the process of installing a vac guage today in my 81 F150 2wd with a 300... like going to drill a hole this afternoon.

When you guys run the gauge to the engine, do u use a hard line, like brake line, and small rubber lines at the ends for flex, or do you just run rubber line the entire way?

 

I used hose all the way, but that was probably only 2' 6". The shorter, the better.