"Vacuum Robbing" Camshaft and vacuum reservoirs/pumps

[mrWizard]

So, I noticed that 2010 SS doesn't have the same braking performance it used to, after having a camshaft installed. I can stand on the pedal and the tires don't squeal and the ABS doesn't kick in, which cause the car to take some time to stop in an emergency situation. I measured the vacuum from the intake manifold to the booster at ~8-10 in.

I've tested my booster to make sure it is air tight with no leaks, it is. I also checked the check valve, that is working fine. So does anyone have any experience with this? Am I going to need to install a reservoir or pump to increase my vacuum pressure? Or can tuning the vehicle differently increase my vacuum pressure from the booster?

Thanks in advance.

[olblue75]

I had the issue years ago a 71 C10 I had, I put in a big ole narly cam and all but lost my power brakes, but it was a automatic and I put a stall converter in it it helped a little, i think it has something to do with the overlap. I think a vacuum tank would help just dont know how to plumb it in.

[HOJO]

If I remember correctly, once cam duration reaches a certain point you begin to loose engine vacuum. This of course begins to affect anything that operates off of vacuum. Sorry I can not tell you at what point that is though. I'm sure someone will chime in with more knowledge.

[mrWizard]

Originally Posted by HOJO

If I remember correctly, once cam duration reaches a certain point you begin to loose engine vacuum. This of course begins to affect anything that operates off of vacuum. Sorry I can not tell you at what point that is though. I'm sure someone will chime in with more knowledge.

Hmmm, sounds like that would make sense. For anyone else that could chime in about this, here are the specs on my cam:

231/243 @.05 .617/.623 113

Originally Posted by olblue75

I had the issue years ago a 71 C10 I had, I put in a big ole narly cam and all but lost my power brakes, but it was a automatic and I put a stall converter in it it helped a little, i think it has something to do with the overlap. I think a vacuum tank would help just dont know how to plumb it in.

Yeah the more I read, it seems like the vacuum tank is the way to go. Here is some info from one manufacturer on installation.

http://www.jegs.com/InstallationInst...70-99590-1.pdf

[CamaroSS sleeper]

I'm on the same boat on this one...
Interested to know how people are dealing with this.

also mine been turbo, when I go into boost I loose all booster power.
so doing those cool in place burnouts is absolutely impossible.
going off of boost and hitting the breaks, like in an emergency!
there is brake lag about 1-2 seconds.. but it feels like an eternity..

[mrWizard]

Originally Posted by CamaroSS sleeper

I'm on the same boat on this one...
Interested to know how people are dealing with this.

also mine been turbo, when I go into boost I loose all booster power.
so doing those cool in place burnouts is absolutely impossible.
going off of boost and hitting the breaks, like in an emergency!
there is brake lag about 1-2 seconds.. but it feels like an eternity..

I don't know too much about turbo setups, but as long as you are making some increasing vacuum while driving, the vacuum reservoir will hold it for when you go to brake. Should eliminate you having to wait for vacuum again. And they are relatively cheap. Around $40-60.

[JerTM]

An electric vacuum pump would help this.

[christianchevell]

A cool in place burnout is done with a line lock kit..... You could read up on the effects of LSA with a article by comp cams.........

http://www.compcams.com/Pages/413/ca...ion-angle.aspx



Effect Of Changes In Cam Timing And Lobe Separation Angle

The following tables illustrate how variations in lobe separation angle and cam
timing will effect the behavior of the engine in which the camshaft is installed.



EFFECTS OF ALTERING CAMSHAFT TIMING


Advancing Retarding
Begins Intake Event Sooner Delays Intake Closing Event
Open Intake Valve Sooner Keeps Intake Valve Open Later
Builds More Low-End Torque Builds More High-RPM Power
Decrease Piston-Intake Valve Clearance Increase Piston-Intake Valve Clearance
Increase Piston-Exhaust Valve Clearance Decrease Piston-Exhaust Valve Clearance





EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA)


Tighten (smaller LSA number) Widen (larger LSA number)
Moves Torque to Lower RPM Raise Torque to Higher RPM
Increases Maximum Torque Reduces Maximum Torque
Narrow Power band Broadens Power Band
Builds Higher Cylinder Pressure Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock Decrease Chance of Engine Knock
Increase Cranking Compression Decrease Cranking Compression
Increase Effective Compression Decrease Effective Compression
Idle Vacuum is Reduced Idle Vacuum is Increased
Idle Quality Suffers Idle Quality Improves
Open Valve-Overlap Increases Open Valve-Overlap Decreases
Closed Valve-Overlap Increases Closed Valve-Overlap Decreases
Natural EGR Effect Increases Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance Increases Piston-to-Valve Clearance





CAMSHAFT GEOGRAPHY AND LOBE FUNCTION


effects Of Changes In Cam Timing And Lobe Separation Angle

The following tables illustrate how variations in lobe separation angle and cam
timing will effect the behavior of the engine in which the camshaft is installed.



EFFECTS OF ALTERING CAMSHAFT TIMING


Advancing Retarding
Begins Intake Event Sooner Delays Intake Closing Event
Open Intake Valve Sooner Keeps Intake Valve Open Later
Builds More Low-End Torque Builds More High-RPM Power
Decrease Piston-Intake Valve Clearance Increase Piston-Intake Valve Clearance
Increase Piston-Exhaust Valve Clearance Decrease Piston-Exhaust Valve Clearance





EFFECTS OF CHANGING LOBE SEPERATION ANGLE (LSA)


Tighten (smaller LSA number) Widen (larger LSA number)
Moves Torque to Lower RPM Raise Torque to Higher RPM
Increases Maximum Torque Reduces Maximum Torque
Narrow Power band Broadens Power Band
Builds Higher Cylinder Pressure Reduce Maximum Cylinder Pressure
Increase Chance of Engine Knock Decrease Chance of Engine Knock
Increase Cranking Compression Decrease Cranking Compression
Increase Effective Compression Decrease Effective Compression
Idle Vacuum is Reduced Idle Vacuum is Increased
Idle Quality Suffers Idle Quality Improves
Open Valve-Overlap Increases Open Valve-Overlap Decreases
Closed Valve-Overlap Increases Closed Valve-Overlap Decreases
Natural EGR Effect Increases Natural EGR Effect is Reduced
Decreases Piston-to-Valve Clearance Increases Piston-to-Valve Clearance



Good Luck.

[mrWizard]

Little update:

Ended up putting in a vacuum canister. Holds vacuum and after revving it holds over 20 in and makes a difference when using the brakes. Not the best fix, but it works. Ended up mounting it to the positive battery terminal position after moving to over to the stock air intake filter bolt. It's the only area it would fit.

Went with this canister and vacuum gauge:
http://www.amazon.com/Mr-Gasket-3701...ilpage_o05_s00

http://www.amazon.com/1-1-Vacuum-Gau...ilpage_o00_s00

[WHAMMO]

I lostbrake power too with my 231 236 on 111 lsa..might need this.