# DIY: How to calibrate your Autometer mechanical boost gauge



## mechsoldier (Aug 14, 2004)

I bought a boost gauge off ebay, but when it got here I discovered it read 11 inches of vacuum all the time for some reason. I googled on the net and I discovered that a lot of people were having this problem but nobody really had any idea how to fix it. So I opened it up and figured it out. First off, open up the gauge. By uncrimping the bezel ring with a screwdriver or knife. Take off the hose barb from the copper pipe fitting coming out of the gauge and remove the nut that holds the fitting to the outside of the housing.
The face will now fall out.








Basically air fills the flat copper tube and makes it expand, or vacuum makes it contract. 








The white plastic piece is connected to the armature that moves the needle. Using something small enough to get in there, compress the the point so it will exit through the hole.








Now you need to move this piece, expanding it further away from the copper tube makes the needle move further toward 30 psi, pushing it back in towards the copper tube will make the needle drop towards vacuum. Try your hardest not to move the actual copper tube as this may effect the calibration. Check often, what I was just press the white plastic connector only partially in and checked for needle position.
When I was done I just hooked it up to an air compressor after I drained the air down to around 25 psi and checked the gauge, it registered the same as the air compressor gauge so we're good....












_Modified by mechsoldier at 7:49 AM 1-14-2006_


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## xpalendocious (Nov 28, 2003)

awsome!


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## Loren Wallace (Oct 15, 2005)

nice job, i never would of thought of trying to mess around with a boost gauge


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## jwatts (Mar 11, 2001)

*Re: (J Eagan)*

I think the needle can be pulled off and reclocked.
I had a 0-30psi gauge that read 10psi with the engine off. Had to clip the 0psi needle stop off of the face and reclock the needle.


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## mechsoldier (Aug 14, 2004)

*Re: (jwatts)*

It's possible, but the needle also has a limited sweep, it's possible that it may not be correct after this due to the spring tension. You already have the face off, you might as well bend the copper piece.


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## jwatts (Mar 11, 2001)

*Re: (mechsoldier)*

with the 0-30psi gauge, the needle had slipped when the engine was under vacuum.


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## 1.8TurboGLI (Sep 19, 2004)

*Re: (jwatts)*

Perfect gotta try it..


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## sp_golf (Nov 28, 2007)

*Re: (mechsoldier)*


_Quote, originally posted by *mechsoldier* »_It's possible, but the needle also has a limited sweep, it's possible that it may not be correct after this due to the spring tension. You already have the face off, you might as well bend the copper piece.

Adding to this thread:
I corrected mine by skipping the needle gear about 2 teeth, I didn't pull the needle out, I just held the gear that goes onto the needle's gear with a small flat head and skipped the needle.
It reads 0 now when there is no vacuum and reads properly in vacuum and boost(I have a Greddy Boost controller which displays boost as reference)


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