badjuju Posted October 4, 2006 Share Posted October 4, 2006 My vaccuum is about 9 inches hg at idle, it uh, doesn't seem normal... So I'm wondering if some people can post their pressures at idle? l28et 286,000 miles Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 4, 2006 Author Share Posted October 4, 2006 Nothin? Quote Link to comment Share on other sites More sharing options...
Dayz Posted October 4, 2006 Share Posted October 4, 2006 Search for a post by Grumpyvette talking about vaccuum guages ! There is a link of a lot of info just by reading the vaccuun guage. Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 4, 2006 Share Posted October 4, 2006 18-22 PSI at idle. Not sure what that is in Hg Quote Link to comment Share on other sites More sharing options...
73240ZT Posted October 5, 2006 Share Posted October 5, 2006 My stock engine idles at 19.5 inch of vacuum. Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 5, 2006 Author Share Posted October 5, 2006 20 psi converts to 40.72 inches of mercury... this is a big problem, is it not? Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 6, 2006 Share Posted October 6, 2006 Er yeah, it's not 18-22psi, it's 18-22 inches Hg. I'll lay money on it. If you have a stock EFI Z with that low a vacuum, it's affecting the fuel delivery. Check valve adjustment... Mine is anywhere from 12 to 20" Hg depending on what cam I'm running. I want to say the stock L28ET in the 260 has something like 35kpa at idle. Good Luck. Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 6, 2006 Author Share Posted October 6, 2006 I got kinda confused with whether the gauge meant ambient minus 9 hg, or just 9 hg, so i plugged my lappie in and got a reading of 35-43 kpa at idle, at 1500 rpm. My rpm is so high because when i put it into drive it drops down to about 900, where it will die if it goes much lower. not sure if it dies because the auto pulls it down so far or because it's tuned poorly, so i'm going to try and play with that this weekend too. however, i'm kinda concerned with my gauge reading, because you say 12-20 depending, and that stock is something like 35. if that's correct, i need to better understand the reading of my little gauge, because my understanding is taht kpa is in absolute value, ie, 100 = ambient, then any vaccuum is under 100, and boost is over 100, give or take a couple kpa due to alt and temp. that is, 1 atm is equal to ~14.7 psi, so i would assume that a 10 psi vaccuum would mean it's actually at 4.7 psi, or ambient-10. I don't however know the conversion setup for inches hg to kpa. Tony, do you think that there is an issue with my kpa being 35, and if so, it's strictly a tuning issue? Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 6, 2006 Author Share Posted October 6, 2006 IDEA! K, get this; my gauge reads Inches Hg on the vaccuum side, and psi on the boost side. Say it's broken, say it's actually just reading psi on both sides. It's possible i suppose... anyways If that's the case, and it's actually reading 9 psi and showing 9 psi, there are 2.036 inches of mercury in 1 psi. that means 9 psi is about 18.32 inches of mercury, which computes to 62 kpa. ambient (100 kpa) pressure - 62 kpa vaccuum = 38 kpa, my average kpa value for pressure at idle. any takers? anyone buying this, or am i off my rocker? Quote Link to comment Share on other sites More sharing options...
Guest 280ZForce Posted October 6, 2006 Share Posted October 6, 2006 mine reads -9 in hg...but then again mine has a pretty agressive cam Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 6, 2006 Author Share Posted October 6, 2006 Any comments on my conversion idea? Quote Link to comment Share on other sites More sharing options...
naviathan Posted October 6, 2006 Share Posted October 6, 2006 Oops...Yeah that was suppose to be 18-22 in. Sorry about that. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted October 6, 2006 Share Posted October 6, 2006 So what are your cam specs? Big cams make for low vacuum readings and high idles. Quote Link to comment Share on other sites More sharing options...
badjuju Posted October 8, 2006 Author Share Posted October 8, 2006 Stock l28et. lol Also, megasquirt is giving the right number, my vaccuum gauge is broken autometer wants to send me another one. thanks for the help guys! Quote Link to comment Share on other sites More sharing options...
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