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Author
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Topic: Uh oh...vacuum gauge is not happy
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: Oct 99
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posted 11-20-2002 06:06 PM
   
So i went out and got a cheapo-matic vacuum guage to test my vacuum and make sure everything is happy.
Plugged Cheapo-matic into the PCV valve on the intake manifold and distressingly it only rang up around 10-12 HG in.
So seeing that this is a BAD thing on a freshly rebuilt(again) motor. I was curious. What is this?
I checked around my intake for any vacuum leaks. Couldnt seem to find anything that was sucking. Timing is set to 14@1000 rpm advance with 38 degress total timing. Carb-to-manifold gaskets seemed ok but obviously something is wrong.
Can anyone off any advice?
maybe my springs are too heavy? could it be anything internal? in the heads? or can that only be caused by a vacuum leak?
It doesnt jump around....Just kinda sits and 1o or so unless I rev it up. then it shoots up to about 25 and comes back down.
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kid vishus
Gearhead Posts: 3894
From: middle of NC
Registered: Oct 2000
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posted 11-20-2002 06:16 PM
How big is your camshaft? That primarily dictates the amount of vacuum. A big cam wont have much vacuum. The last motor I put a vacuum guage on only showed 5" at idle.
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: Oct 99
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posted 11-20-2002 06:26 PM
pretty big I suppose
Comp cams 270H(.519"/.519" 224/[email protected]" {270/270}).
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kid vishus
Gearhead Posts: 3894
From: middle of NC
Registered: Oct 2000
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posted 11-20-2002 06:32 PM
That's not that big. But I'm not positive, but I bet 10-12 isnt out of line. Hopefully someone who knows more about such things will answer.
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Dave Gibson
Moderator Posts: 6819
From: Pensacola, Florida, USA M&M#166 MCA#47921
Registered: Aug 99
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posted 11-20-2002 07:14 PM
Wulfgar,
I'm running about the same size cam in our 289 4V.  My vaccum pressure was running about the same as yours. After some fine tunning with advance, dwell and carb adjustments, we got it up to the 12 - 14 range. We used the same port at the rear of the carb spacer to check vaccum.Dave & Terri ------------------
Poison Ivy (Dave's)
'65 Fastback Modified 289 4V, C-4, dual exhaust, styled steel wheels, rally pac, A/C
'02 Explorer XLT, Black, 3.73:1 limited slip, class III tow package!
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steve'66
Gearhead Posts: 5659
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 11-21-2002 06:42 PM
Yes,Adjust your idle screws with the vacumm gauge for max vac. Then reset your idle speed and timing, then adjust idle screws again, and reset the idle speed and timing again. You should be able to pick up 3-4"s. Good luck, SteveW [This message has been edited by steve'66 (edited 11-21-2002).]
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johnmustang
Gearhead Posts: 3349
From: Vancouver Island , British Columbia , Canada
Registered: Nov 2001
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posted 11-21-2002 06:58 PM
Had the same problem with my freshly rebuilt 289 with a 268h comp cam. If you have power brakes and such it will take some away from you , but , with some tweeking and playing around I got mine up to 13-15 inches , I am sure you can do the same. JOHN ------------------
65 2+2 FASTBACK
68 COUPE (SOLD)
87 TAURUS WAGON
98 F150 XLT TRITON V8 4.6, 4 WHEEL DRIVE
Member:Vancouver Island Mustang Association
M&M #1710
MyPhotoPage
MY TRUCK
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johnmustang
Gearhead Posts: 3349
From: Vancouver Island , British Columbia , Canada
Registered: Nov 2001
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posted 11-21-2002 07:03 PM
Wulfgar , Just wanted to ask if that is your real name or screen name ? The reason I ask is that it is a little bit unusual , and , it is the name of an on going character in a series of books that I read ( Forgotten Realms , Dragon Lance , Thieves World ). Just curious , don,t feel you have to answer if this question is to intrusive. JOHN ------------------
65 2+2 FASTBACK
68 COUPE (SOLD)
87 TAURUS WAGON
98 F150 XLT TRITON V8 4.6, 4 WHEEL DRIVE
Member:Vancouver Island Mustang Association
M&M #1710
MyPhotoPage
MY TRUCK
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: Oct 99
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posted 11-21-2002 11:24 PM
quote:
Originally posted by johnmustang:
Wulfgar , Just wanted to ask if that is your real name or screen name ? The reason I ask is that it is a little bit unusual , and , it is the name of an on going character in a series of books that I read ( Forgotten Realms , Dragon Lance , Thieves World ). Just curious , don,t feel you have to answer if this question is to intrusive. JOHN
You know your fantasy. Wulfgar was Drizzts Barbarian friend in the Forgotten Realms ongoing series about those heros. The reason that name kinda stuck on me is because, like Wulfgar, am a big guy(6'4" 295 lbs, competitive powerlifter/olympic lifter). In high school me and all my friends read the books and the name stuck on me. hehe nice to see another FR fan in here. 
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: Oct 99
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posted 11-21-2002 11:26 PM
quote:
Originally posted by steve'66:
Yes,Adjust your idle screws with the vacumm gauge for max vac. Then reset your idle speed and timing, then adjust idle screws again, and reset the idle speed and timing again. You should be able to pick up 3-4"s. Good luck, SteveW [This message has been edited by steve'66 (edited 11-21-2002).]
Got my new Mighty Demon 650 comin in on monday. Im going to kee the car off till then. And when I adjust the Demon Ill use the vac guage and try that with the idle screws.
Question though. When you are checking the vacuum as you are adjusting the carb, does it matter where you hook your vac gauge on the intake manifold?
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steve'66
Gearhead Posts: 5659
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 11-21-2002 11:36 PM
You've got the right place. The egr valve's hose is perfect. Good luck,SteveW
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