Is 20 inches/ 50 centimeters of vacuum good or bad?
03-28-2011, 04:02 PM
#1
Teching In
Thread Starter
Join Date: Mar 2011
Location: Bloomington, MN
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
Is 20 inches/ 50 centimeters of vacuum good or bad? i just tested my fuel pressure from the fuel pump regulator and it showed 20 inches hg(or hq or something) and 50 centimeters hg or whatever for the vacuum. imm wondering if thats good pressure or if its low or high
03-28-2011, 04:18 PM
#3
Teching In
Thread Starter
Join Date: Mar 2011
Location: Bloomington, MN
Posts: 29
Likes: 0
Received 0 Likes
on
0 Posts
ive been testing my car for weeks and i still cant figure out whats wrong with it. When i drive itll do perfect in first gear but either in 2nd, 3rd, or 4th it does this wierd bog thing where it just drops rpm's and wont accelerate fast at all like when your a gear or 2 above what you should be. If i floor it itll clear until i let up on the peddle again. It seems alot slower then it should be to. any ideas?
03-28-2011, 05:42 PM
#4
TECH Regular
Join Date: May 2010
Posts: 481
Likes: 0
Received 0 Likes
on
0 Posts
http://shbox.com/1/fp_reg.jpg
Is that where your hooking into? With a fuel pressure gauge? If its reading 20lbs, then that's about half of what it should be (43lbs). Unplug the vaccum line with the gauge hooked up and report back what it reads
Is that where your hooking into? With a fuel pressure gauge? If its reading 20lbs, then that's about half of what it should be (43lbs). Unplug the vaccum line with the gauge hooked up and report back what it reads
03-28-2011, 06:05 PM
#5
http://shbox.com/1/fp_reg.jpg
Is that where your hooking into? With a fuel pressure gauge? If its reading 20lbs, then that's about half of what it should be (43lbs). Unplug the vaccum line with the gauge hooked up and report back what it reads
Is that where your hooking into? With a fuel pressure gauge? If its reading 20lbs, then that's about half of what it should be (43lbs). Unplug the vaccum line with the gauge hooked up and report back what it reads
Trending Topics
03-28-2011, 07:23 PM
#8
03-28-2011, 07:39 PM
#9
That's what I used when I had the same cam in my 350.
03-28-2011, 07:54 PM
#10
Had one that Comp gave me for free during the 918 beehive fiasco. It did nothing but in all fairness at the time, the booster had an issue where it would not hold air. There was a gouge in the piston that caused it to bleed off air along with what was in the cannister. I sold the cannister with the custom made mount for $100 and got the vaccum pump off Ebay for $150 so there is not much money invested. Maybe now the cannister would work better but the pump is up and running and will still be superior to the cannister.
03-28-2011, 09:15 PM
#12
Village Troll 
iTrader: (2)
I'm not sure what you are getting at, but there's nothing official about the 211 cam. It's not a popular choice in the slightest even though it can trump most any other cam that is relatively close to its grind.
03-28-2011, 09:29 PM
#13
Maybe I am being overly picky than the average Joe but if the vacuum spec for the booster is X I would like to meet or exceed it at all times cause brakes are kind of important.
Also I honestly believe if there were underlying problems the BLMs would be totally frigged up because with the slightest vacuum leak, they go completely to Hell.
03-28-2011, 09:40 PM
#15
Why is it a crap cam? Cause it cant produce 15" of vaccum which is my only real concern. By that definition there is a lot of crap cams on this board. The way I see it, the problem was addressed, the spec is satisfied and the car runs great and I dont have the money or desire to swap cams. I actually want to drive the car and enjoy it.
That said I can get a AI cam of similar duration cam and still not meet the brake booster vacuum spec according to Speeds comment above. Speeds car is strong and fast and he certainly does not have a crap cam simply because it cant make 15" of vacuum.
Bottom line is the greater the vacuum to the booster, the better the braking without having to apply increased pressure at the pedal meaning closer to the way it was with the stock cam.
That said I can get a AI cam of similar duration cam and still not meet the brake booster vacuum spec according to Speeds comment above. Speeds car is strong and fast and he certainly does not have a crap cam simply because it cant make 15" of vacuum.
Bottom line is the greater the vacuum to the booster, the better the braking without having to apply increased pressure at the pedal meaning closer to the way it was with the stock cam.
Last edited by wrd1972; 03-28-2011 at 09:59 PM.
03-28-2011, 10:17 PM
#16
Again it appears to be the 107 LSA which means lots of overlap which kills vacuum. Let me clarify that without the pump, the brakes work and the car will stop but I can detect it takes more effort than what it did with the stock cam. Obviously the is significant more assist with 20" of vacuum vs. 8" so the pedal is absolutely gonna feel different.
Maybe I am being overly picky than the average Joe but if the vacuum spec for the booster is X I would like to meet or exceed it at all times cause brakes are kind of important.
Also I honestly believe if there were underlying problems the BLMs would be totally frigged up because with the slightest vacuum leak, they go completely to Hell.
Maybe I am being overly picky than the average Joe but if the vacuum spec for the booster is X I would like to meet or exceed it at all times cause brakes are kind of important.
Also I honestly believe if there were underlying problems the BLMs would be totally frigged up because with the slightest vacuum leak, they go completely to Hell.
There has to be some underlying problem, it could be anything from glazed brake pads to you running some autozone special pads, or a vacuum leak somewhere. What is you idle speed set at?
03-28-2011, 10:27 PM
#17
Idle is 900 RPM and I recently installed a new set of Hawk HPS plus dont forget what I stated above. At the time I was chasing the problem, the booster was unknowingly bleeding of vacuum. In fact you could actually hear it weezing when the motor was turned off.
Chances are if I disconnected the pump, the booster would retain high vacuum without bleeding off like before meaning they might work perfectly fine the way you guys say it should. The pump is now ensuring that the brake spec is satisfied at all times which is desirable and the car stops agressively every bit as good as it did with the stock cam was providing ~20" of vacuum.
Chances are if I disconnected the pump, the booster would retain high vacuum without bleeding off like before meaning they might work perfectly fine the way you guys say it should. The pump is now ensuring that the brake spec is satisfied at all times which is desirable and the car stops agressively every bit as good as it did with the stock cam was providing ~20" of vacuum.
