Mile High Vaccum Check

BlackMamba50

BlackMamba50

#10pistonkilla
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Well I did a vacuum check this afternoon. Reading 5-6 inches HG. I had a few other threads bitching about my brakes since moving up here to the Mile High City. Now that I have a bigger cam I for sure don't have brakes now. Opinions needed. Torrie will be doing my tuning. Prob get a break in tune from him before hitting the dyno. Is there something wrong, maybe a restriction or cracked line or is the altitude combined with the cam really that much of a factor for the low vacuum reading? Similar set-up on the East Coast had a vacuum reading of 10-11 inches of HG. Maybe I need an electric vacuum pump. I'm all ears on this one.

[ame=http://www.youtube.com/watch?v=k5WKY8Hi9PI]Big cam idle vacuum test - YouTube[/ame]

 
Last edited:
Any specs on the cam? What's your compression ratio?

Your cam could have too much overlap for your compression ratio. Also having all this info will help Torrie get your tune spot on.
 
mysrt10 said:
Any specs on the cam? What's your compression ratio?

Your cam could have too much overlap for your compression ratio. Also having all this info will help Torrie get your tune spot on.
Click to expand...

Compression ratio 9.80
Torrie has this info as well!

 
BlackMamba50 said:
Well I did a vacuum check this afternoon. Reading 5-6 inches HG. I had a few other threads bitching about my brakes since moving up here to the Mile High City. Now that I have a bigger cam I for sure don't have brakes now. Opinions needed. Torrie will be doing my tuning. Prob get a break in tune from him before hitting the dyno. Is there something wrong, maybe a restriction or cracked line or is the altitude combined with the cam really that much of a factor for the low vacuum reading? Similar set-up on the East Coast had a vacuum reading of 10-11 inches of HG. Maybe I need an electric vacuum pump. I'm all ears on this one.

Big cam idle vacuum test - YouTube

Click to expand...

It's your tune. I basically have the same setup as you. After my build, my vaccum was all screwed up and throwing rich codes. Torrie hooked me up. No problems after he corrected the tune.
 
ramv10 said:
It's your tune. I basically have the same setup as you. After my build, my vaccum was all screwed up and throwing rich codes. Torrie hooked me up. No problems after he corrected the tune.
Click to expand...

I agree!
 
Uploading drive tune to SCT right now. Thanks Torrie!
 
Well that took up to 7 inches HG, still need more pedal.
 
Well guess I will just buy that summit electric vacuum pump and see what happens.
 
Might try a vaccum chamber? And have you checked your brake booster to make sure its not bleeding off vaccum?
 
ARRESTmeRed04 said:
Might try a vaccum chamber? And have you checked your brake booster to make sure its not bleeding off vaccum?
Click to expand...

Yeah maybe a bad check valve or brake booster. I had everything checked a year ago by Brakes Plus and they couldn't find anything wrong. But 5-6 inches HG, even at this altitude can't be that low. Torrie got it bumped up to 7 inches HG with the tune he sent me.
 
I bet mile high may be having a little bit to do with it but even with 10lbs of vacuum I don't feel it's enough.

I have a built motor with a cam with about the same specs except I'm ground on a 114 and get about 9-10" of vacuum. Stopping feels ok but not convincing for first peddle press but press again and you're quickly out of vacuum. I connected an electric pump and feel so much better for it. I'd love to have a boost a pump that works off of the power steering pump but it's just way too much money in my opinion.
Joe
 
Well I ordered the Summit Racing Electric Vacuum Pump this morning, next day air of course:) I checked the power brake booster and couldn't find any signs of leakage. Checked the vacuum directly into the intake manifold and it was 7 inches hg, so no change in vacuum pressure between the intake manifold & power brake booster. Hopefully this will solve my issues and I can get the beast broken in on the open road this weekend.
 
Sent from my DROID RAZR using Tapatalk 2
 

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Def have a vacuum leak in one of the small lines. Pump wouldn't shut off. Disconnected the two small lines from the check valve on the power brake booster and the pump shut off. Thing is pretty awesome, checked the vacuum on it and when she falls below 15 inches hg she kicks back on. Temp installed right now, I'll get her done tomorrow. Time for beer, been a long week. Brakes feeling better, may need to bleed them after sitting for a year along with rebuilding the front caliper pistons.
 
Well got the electric vacuum pump installed and isolated a leak. I will need to get some rubber isolators to take out the rumble of the pump. Gonna order new brake pads and see if that helps my issues. Wonder if maybe my valves are too tight causing low vacuum. Getting there slowly.



 
I wouldn't think it was the valves if its running good, however you could check the compression for shits and giggles
 
ARRESTmeRed04 said:
I wouldn't think it was the valves if its running good, however you could check the compression for shits and giggles
Click to expand...

She runs pretty good on the highway. I let her have it one good time. I got Torrie paid for so just gotta buy some Dyno time at the shop up here. $100 an hour or a 4 hour block for $300.
 
Just wanted to update on the brake issue. I had the rotors turned today, they didn't look bad at all. I did throw away the Centric pads that I installed before moving here in 2011 and installed EBC Yellow. What a huge difference, I'll spring for the more expensive pads from now on. Also I installed rubber isolators on the mounting area to the vacuum pump, lessened the vibrations a ton! So I will stick with EBC pads, I'll upgrade the brake lines and rotors in the near future. EBC has my vote!
 
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