Vacuum measurment
Thread Starter
|
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
Vacuum measurment
I finally bought a vacuum gauge.
At idle (about 1000 RPM in neutral, this cam seems to like that better) Holding steady at 12-16 in/hg. And dropping to 0 and spiking to 21 when I hit and release the throttle. The instructions say that this represents leaking piston rings.
Does this sound right? Does my long duration cam make this analysis invalid?
Cam Specs Crower Power Beast
Grind Lobe Center :292H/112D
Advertised Duration (Intake): 292, (Exhaust) : 302
Duration @ 0.50 in. (Intake) : 214, (Exhaust) :224
Gross Lift(1.76/1.76) (Intake): .521", (Exhaust): .547"
At idle (about 1000 RPM in neutral, this cam seems to like that better) Holding steady at 12-16 in/hg. And dropping to 0 and spiking to 21 when I hit and release the throttle. The instructions say that this represents leaking piston rings.
Does this sound right? Does my long duration cam make this analysis invalid?
Cam Specs Crower Power Beast
Grind Lobe Center :292H/112D
Advertised Duration (Intake): 292, (Exhaust) : 302
Duration @ 0.50 in. (Intake) : 214, (Exhaust) :224
Gross Lift(1.76/1.76) (Intake): .521", (Exhaust): .547"
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
Vacuum measurment
I may be incorrect but a fluctuating guage even though it indicates bad rings on a stock engine will do the same on an engine with a large advertised duration. You seem to be pulling decent vaccum with that cam even though it is not steady. Get some more inputs first. Like I said I have been wrong before and am certain to be wrong again.
Thread Starter
|
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
Vacuum measurment
It's steady at a steady RPM, just lower than the gauge instructions say is typical. Jumping around when hitting the throttle is expected , according the instructions.
Certified Thread Hijacker
Joined: Aug 2001
Posts: 14,441
Likes: 60
Vacuum measurment
with a 230 @ .050 I got around 10-11 HG at idle. Very steady needle.
With my 204 I am getting around 16 I believe.
And my gauge jumped around as well with I blipped the throttle.
Josh
With my 204 I am getting around 16 I believe.
And my gauge jumped around as well with I blipped the throttle.
Josh
Junior User
Joined: Oct 2002
Posts: 57
Likes: 0
From: Fairborn USA
Vacuum measurment
I run a Vacuum guage in my truck at all times. When you blip the throttle your vacuum will drop then as you close the throttle plates it will increase and as the engine slows back down the vacuum will drop, This is normal. Mine runs at 21 at idle and around 18 while crusing. If I blip mine it peaks around 25. Also the higher you keep the vacuum while driving the better the gas milage will be.
Tim
My Truck
http://1969ford.ods.org/mytruck.htm
Tim
My Truck
http://1969ford.ods.org/mytruck.htm
Thread Starter
|
Lead Driver
Joined: Apr 2001
Posts: 6,175
Likes: 21
From: Texas
Vacuum measurment
The engine was rebuilt about 10,000 miles before I got it. I've probably put 5000 on it since. I really didn't want to believe that rings were bad. I figured the cam was probably the suspect.
Thanks for helping ease my tension.
The gauge is also supposed to measure the pressure of the fuel pump. What should I be looking at, around 5-6 PSI?
Thanks for helping ease my tension.
The gauge is also supposed to measure the pressure of the fuel pump. What should I be looking at, around 5-6 PSI?
Trending Topics
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
Vacuum measurment
Anywhere from 5-7 psi should be good for fuel pressure. If your holley is a dual feed you can get a cool fuel line with a guage in it so you will always know where it is at. I think it is 40 bucks. You can see it on my engine on my homepage. Wait a sec. I just saw you are running a edel carb. I think edels don't like anything higher that 5psi but you may see what somebody that actually owns an edel carb says. I know they don't like as much pressure as the holley carbs do.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Certified Thread Hijacker
Joined: Aug 2001
Posts: 14,441
Likes: 60
Vacuum measurment
I have heard that before about AFB carbs, but it isn't true.
I run 6 psi (Holley pump) with either my 600 Carter or my 750 Edelbrock with no ill wills.
And just look at Edelbrock's own line of fuel pumps. The Performer cranks out 6 psi with no external regulator needed and their Victor pumps put out 14 with the recommended regulator set at 7.
Where I beleive the problem begins is some AFB carbs come with spring loaded needle and seats while others don't. When a rebuild kit is used with the standard needle n seats the float setting is now very high.
Some people just do not realize this and do not bother to check the float height.
Josh
I run 6 psi (Holley pump) with either my 600 Carter or my 750 Edelbrock with no ill wills.
And just look at Edelbrock's own line of fuel pumps. The Performer cranks out 6 psi with no external regulator needed and their Victor pumps put out 14 with the recommended regulator set at 7.
Where I beleive the problem begins is some AFB carbs come with spring loaded needle and seats while others don't. When a rebuild kit is used with the standard needle n seats the float setting is now very high.
Some people just do not realize this and do not bother to check the float height.
Josh
Thread
Thread Starter
Forum
Replies
Last Post
CowboyFromHell
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
4
Apr 22, 2009 11:08 PM
76 F150 Ranger XLT
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
5
Oct 1, 2004 07:34 AM
gtex
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
23
Oct 6, 2002 04:08 PM
gtex
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
7
Feb 21, 2002 03:31 PM
gtex
FE & FT Big Block V8 (332, 352, 360, 390, 406, 410, 427, 428)
2
Aug 22, 2001 08:19 AM
