Vaccuum Gauge Issues/ IDLE - Team Camaro Tech
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post #1 of 13 (permalink) Old Mar 17th, 10, 05:24 PM Thread Starter
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Kip
 
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Vaccuum Gauge Issues/ IDLE

What would cause the needle of a vacuum gauge to shake violently between 9"an 14" at 1000rpm. This is on a 350. 15* initial, 34* total, with vacuum advance not hooked up...
The engine idles rough too.... I have been having a heck of a time getting this freak'n thing to run like I think it should... and I am starting to wonder if it is not an internal issue.
Any info on the vacuum gauge issue would be appreciated...

Kip.....
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post #2 of 13 (permalink) Old Mar 17th, 10, 05:25 PM
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Re: Vaccuum Gauge Issues/ IDLE

When this happens could it be a draw from electric fans kicking on... Also when the vacuum drops dose the rpm drop to.

I NEED TO HIT THE LOTTERY
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post #3 of 13 (permalink) Old Mar 17th, 10, 05:27 PM
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Re: Vaccuum Gauge Issues/ IDLE

http://www.centuryperformance.com/tu...e-spg-148.html


http://www.tuningmadeeasy.com/tuning...e-wonder-tool/

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'02 Z/28 vert-stock-sold and totaled
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post #4 of 13 (permalink) Old Mar 17th, 10, 05:37 PM
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Re: Vaccuum Gauge Issues/ IDLE

Not good. When exploring the above links, pay attention to the part about bad valves. Also run a compression check. Also be planning your tear down. Oh, IMHO or course.

One owner 69 Camaro,(yep, bought it new
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post #5 of 13 (permalink) Old Mar 17th, 10, 05:43 PM
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Re: Vaccuum Gauge Issues/ IDLE

Nice links Steiner

I NEED TO HIT THE LOTTERY
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post #6 of 13 (permalink) Old Mar 17th, 10, 05:56 PM
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Re: Vaccuum Gauge Issues/ IDLE

Quote:
Originally Posted by Skeeter55 View Post
Nice links Steiner

Thanks. Can you tell I've had a set of heads rebuilt? Ha ha.

'69 Camaro
Dart 400-AFR 195-224/224 HR-Powerjection III TB with F.A.S.T. Sportsman XFI
TKO 600-Moser 3.42-Detroit Truetrac
500hp/538lbft

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'69 Camaro Beater-SFT 327-M20-Moser 4.10-sold
'02 Z/28 vert-stock-sold and totaled
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post #7 of 13 (permalink) Old Mar 17th, 10, 06:41 PM Thread Starter
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Re: Vaccuum Gauge Issues/ IDLE

I was kinda afraid that it was a bigger issue that just idle mixture screws or timing...
The engine came with the car... and I really have kinda been suspecting its soundness... But, I didnt buy the car for the engine...
Are we talking head issues or or complete rebuild...?
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post #8 of 13 (permalink) Old Mar 17th, 10, 06:55 PM
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Re: Vaccuum Gauge Issues/ IDLE

I'd start simple. Could be that someone over tightened a rocker arm causing a valve to hang open. A compression test is a good first step also.

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post #9 of 13 (permalink) Old Mar 18th, 10, 05:56 AM Thread Starter
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Re: Vaccuum Gauge Issues/ IDLE

Great links... I am gonna do a compression test and also maybe take a look at how I have the wires from my MSD system routed... Thanks for the responses...
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post #10 of 13 (permalink) Old Mar 18th, 10, 04:37 PM
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Re: Vaccuum Gauge Issues/ IDLE

Quote:
Could be that someone over tightened a rocker arm causing a valve to hang open.
This is the most common reason espec on a new engine/head...set cold before 1st start up.....they always need rechecking and again a few 100 miles on the clock...

My Spelling is not incorrect...it is creative

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post #11 of 13 (permalink) Old Mar 18th, 10, 06:19 PM Thread Starter
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Re: Vaccuum Gauge Issues/ IDLE

This is an old engine... that came with the car. Its a 69 block, that was rebuilt about 10 years ago with pretty good parts...
I moved the MSD system and routed all of the wires away from each other... Still doing strange things on the vacuum gauge. Today, I ran the motor up to about 2500rmp. Vacuum went up to about 20" and the needle steadied out.... Previous links in this thread are pointing me to worn valve guides.....
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post #12 of 13 (permalink) Old Mar 18th, 10, 09:03 PM
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Re: Vaccuum Gauge Issues/ IDLE

Worn Valve guides 2 ways to check
1/mark which way the plugs sit in the block pull them out black on to giudes black on the bottom rings
2/ after engine has beenm sitting , usually needs to cool down for slightly worn ..fire up and a big puff of smoke out the rear

Guides have to be really really bad to get the effect you mention and they dont show wear till around 100K to 120,000 miles and run like that up around 180,000 miles nps.

My Spelling is not incorrect...it is creative

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post #13 of 13 (permalink) Old Mar 18th, 10, 10:12 PM
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Re: Vaccuum Gauge Issues/ IDLE

hook up the vacuum advance to a full manifold vacuum, and adjust the idle speed down to compensate for it.
then play with the idle mixture screws.
if that doesn't work, pop the valve covers and readjust the valves- if it has a hydraulic cam, do it with the engine running. then play with the idle screws again.
if that fails, then there is something mechanical going on.

you don't plan sincerity.
you have to make it up on the spot.

wanna hear about 20 years ago when i was too smart to know any better?
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