Can you please read this vacuum gauge (Video included) - Hot Rod Forum : Hotrodders Bulletin Board
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Old 03-11-2012, 07:53 PM
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Can you please read this vacuum gauge (Video included)

Hello everyone, this is my first post. Can someone please read my vacuum gauge and Wide band air fuel ratio indicator and please let me know what's going on with my engine?

(See videos embedded in Post #5)

Here is some back ground info:

Chevy Goodwrench 350, Edlebrock intake, new Holley 600 CFM carb, vacuum advance distributor.

I've got about 19" of vacum at idle but the gauge needle drifts between 18 and 20. Vacuum gauge is hooked up to a full-manifold vacuum port on the carb. All other vacuum ports to the carb and manifold are plugged when I'm testing this.

This is on a new crate motor with less than 5,000 miles on it. It always did this right from the very first time i started it up. I chalked it up to an intake gasket leak since the intake I used during the swap was old and didn't have the best sealing surfaces, and I was starting to notice oil around some of the intake bolts.

Well, I bought and installed a new intake and gaskets and absolutely nothing changed. (no more oil though)

I also have an AEM wideband hooked up and it also fluctuates quite a bit. At idle it's between 13.2-13.8 with a spike to 15 or so every now and then. If I set the idle mixture to 14.6 then the spikes are more frequent and get up to 16.5. It really sounds like its misfiring randomly at this point and if I let it idle like this long enough it eventually dies. So I've got the idle mixture screws set rich to about 13.2.

Timing is set at 15 degrees initial and 36 total (with advance disconnected), all in by 2700 rpm. I'm testing the vacuum with the vacuum advance disconnected and plugged. The timing is dead steady and does not fluctuate.

The vacuum only fluctuates at idle. Anything above idle and it's rock steady and acts completely normal. The plugs all looked normal when I pulled them, just slightly tan.

I haven't bought new plugs, wires and cap yet because all this stuff was brand new when I installed the motor and it had the problem even then.

Any ideas? this has me stumped. I thought the new intake would take care of the problem but it didn't. I'm not sure if this is a vacuum leak or an ignition problem.

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Last edited by 68NovaSS; 03-12-2012 at 12:39 PM. Reason: Violation of guidelines. Please see: general board guidelines.
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Old 03-11-2012, 08:36 PM
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richen it up at idle a little more and add some more timing, see if that helps.
You may need to raise the float level to richen it up.
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Old 03-11-2012, 08:51 PM
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Read the sticky at the top of the forums to see how to imbed a video. I can't open your links either. Says "The URL contained a malformed video ID".
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Old 03-11-2012, 09:40 PM
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