anybody else using a vacuum guage?
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Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
anybody else using a vacuum guage?
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.
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Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
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.
Post Fiend
Joined: Jun 2001
Posts: 5,228
Likes: 5
From: Running Springs CA
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.
Im at 6000ft MSL, but had EFI on everything starting with the '88 Ranger.
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Postmaster
Joined: Apr 2003
Posts: 2,703
Likes: 4
From: Harrisburg, NE
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.
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Post Fiend
Joined: Jun 2001
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From: Running Springs CA
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.
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Junior User
Joined: May 2013
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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
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
Junior User
Joined: May 2013
Posts: 79
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[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
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
Cargo Master
Joined: Aug 2007
Posts: 2,558
Likes: 69
From: New Zealand
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.
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.
Fleet Mechanic
Joined: Oct 2010
Posts: 1,690
Likes: 32
From: Delhi, Iowa
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?
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?
Fleet Mechanic
Joined: Oct 2010
Posts: 1,690
Likes: 32
From: Delhi, Iowa
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?
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?