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my primitive vac guage
I glanced over at my pile of junk and spotted the hand controlled vacuum pump, I kept it to bleed brakes.
on the top was a guage... I did not need it to pump brakes. Moving guage by hand something was sticking and I took it apart to clean. here is what it looks like (simply wanted to share). I calibrated it back to zero, and will use it soon enough. I have never checked my old sube, but do remember a comment on the carb versions, having one of the highest readings ever..will find out soon enough. http://i227.photobucket.com/albums/d...cuumguage1.jpg that copper flat curve seems to be an airtight channel, it responds to vacuum pressure... http://i227.photobucket.com/albums/d...cuumguage2.jpg and this is where it shows a reading. cheap.. and now have two useful tools from one. maybe get an LED light in there somehow, run a hardline into the car. so I can monitor... |
here is the readings for a 1987 carbed subaru
http://i227.photobucket.com/albums/d...aru/250rpm.jpg 250 rpm (not 2500.. this is really 250, and even less) http://i227.photobucket.com/albums/d...ubaru/2000.jpg this is maximum, 22 in Hg of vacuum. I first saw this in the 80s.. waddya know, it is still there. Super Stoich... gotta love the real thing :) and on another note, one to learn safe max psi for boost for an old sube, can learn it from converting inches of mercury to psi (psi because I am american) 22*.4912=10.8064 psi In the little sube world I am in, this was a safe rule of thumb I never got to. (never ran a turbo) and 10.8 psi is .744 bar interesting. of course today and boost and max is like a crack addiction to many, but above is the rule I would follow...I never learned if that worked, but it sounded smart enough. Simply to stay safe within oem mechanical setups. |
That's about where my Toyota 22r idles - inches Hg, not revs. 250rpm? Srsly?
Dang. |
at idle ,intake vacuum flutter is bad .
at hot idle
any flutter in the vacuum gauge needle is bad it may be related to the engine speed of 250 rpm ? retest ; at around 700 rpm , if there is still flutter you have a valve sealing problem does your car have EGR ? if yes , have a look with your eyeballs and make sure it opens around 2k rpm , if it does , your intake vacuum should be lower than 22" if EGR does open , your passages are clogged . disregard this if you do not have EGR and quick quick translation of inches of mercury to PSI is 2 to 1 30"hg = 15psi , more or less so 15"hg = 7.5 psi more or less |
Quote:
it is a HUGE fuel save on the old carb. I only got a quick read on specs typical throughout downdraft vac readings, (all cars) 22 inches HG is a maximum typical for gassers. I do not know what happens beyond that. :rolleyes: Getting too much could be as bad as not enough for the range of stoichial decency. 22 is the high end. |
intake vacuum flutter is bad at any rpm
expect 18 to 21 " at hot idle 18 to 22" at 2k rpm 18" with EGR open 22" with no EGR or EGR not open 0" at WOT 25" at decel following WOT snap . but the single most important intake vacuum measured value is steadiness / smoothness , if there is flutter in the intake vacuum you have a leaking valve and that is never good sometimes at low RPM valve overlap will cause flutter so what is your intake vacuum value at 750 rpm , is there flutter or is it smooth the answer will let you know if your engine has problems , or not . |
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