2 1/4" instruments on the stationary sub panel

[brianm]

So I'm a few months into an engine swap that has evolved, as these things do, into a mini restoration. Tonight I removed the stationary instrument sub panel to make it easier to work behind the panel and that has got me thinking about replacing/upgrading those instruments. My chronometer has never worked so that will definitely have to change. The capillary on my oil pressure gauge is in pretty rough shape so put that on the list too. We are putting an alternator in so I need a new ammeter. The only thing worth keeping seems to be oil pressure.

One gets to dreaming about fancy digital instruments but those all go in 2 1/4" holes. I've seen photos of a row of EI engine gauges in the sub panel so I know it can be done, but I'm curious about the details. Are the existing 2 1/16"-ish holes just opened up to 2 1/4"? Or is a new custom sub panel made? I assume the holes in the main panel need to be opened up, as mine only measure about 1 3/4". I'd be curious to hear from somebody that has done the work. I've tried my best to search the forums but I haven't found much besides some missing images.

(The instrument rabbit-hole get real deep real quick. A setup of EI chronometer, volt/ammeter, oil pressure/temp, and cht/egt comes to about $2000 for the four instruments. For about $3000 I can get an all-in-one unit that does all of that, plus tach and a bunch of other stuff)

[GAHorn]

This Rochester Oil Press ga. is only $55 and will fit a 2-1/16” hole perfectly. You may wish to have an instrument shop add red lines to the face. (Or you might purchase it thru someone such as Keystone and they might supply it with the proper markings.). Don’t forget to purchase a new adaptor which matches the filter/screen boss.

(I’ve found many so-called 2-1/4” gauges actually fit a 2-1/16” hole fine.)

https://www.aircraftspruce.com/catalog/ ... press3.php

[ghostflyer]

I have fitted the EI small digital instruments and found them to be very accurate and worth every penny. Yes I had some issues [not EI fault] but they really came to the party. When things get ugly ,the instruments have a very bright warning lights that catch your attention. Plus they self test every time you switch on power. I would be replacing the oil temp/press. gauge first as there isn’t any “wet line “ to break and slowly replace the other gauges as finances allow.

[hilltop170]

When I had EI instruments installed, we took a Dremel tool and carefully enlarged the undersized holes to take the 2-1/4" EI instruments. There is still enough of the rounded edges left to still look good. It throws lots of chips so mask everything as best you can. I have never had a problem with any of the EI instruments since they were installed in 2006, they have worked perfectly. I have called EI customer support several times and have always been treated very well. I did not want to cut up the panel for one of the all-in-one instruments and at first glance, the panel still looks "somewhat" original.

[Karl Towle]

I might mention Aerospace Logic. They have a really nice combination Oil Pressure & Oil Temperature, both digital and analog readouts, all in the same 2-1/4" gauge. http://www.aerospacelogic.com/index.php ... uct_id=130 You'll finally know what your oil temperature actually is.

As for opening up the holes, I used a new (thus sharp) 2-1/4" hole saw. I had to clamp or screw a centering hole plate (scrap aluminum or steel) carefully centered behind the original hole. Then with a helper holding the shop vac, I drilled it out to 2-1/4. Now the really handy trick is if you can get the face off of an old 2-1/4" instrument and put it in the new hole outside in. Then, hold it squared up while a helper uses the proper sized centering punch to establish the exact center of each mounting hole. Drill the holes out to fit #6 screws, and you're done. It will look like factory, and you can install a standard 2-1/4" gauge of your choice.

[DaveF]

I also used a hole saw to enlarge a 2-1/16" to 2-1/4". With a 2-1/4" hole saw, drill holes in 3/4" plywood, leaving the plugs in the saw cup. The Lenox brand hole saw I used made plugs of 2-1/16" OD, which fit neatly into the hole to be enlarged. When the plug extends beyond the teeth of the hole saw, insert it into the 2-1/16" hole and carefully drill it out to 2-1/4".

[ghostflyer]

Dave,
Just tried your method and it works great . Thank you for that .

[AWilson]

I also used a hole saw to enlarge a 2-1/16" to 2-1/4". With a 2-1/4" hole saw, drill holes in 3/4" plywood, leaving the plugs in the saw cup. The Lenox brand hole saw I used made plugs of 2-1/16" OD, which fit neatly into the hole to be enlarged. When the plug extends beyond the teeth of the hole saw, insert it into the 2-1/16" hole and carefully drill it out to 2-1/4".

This is a great idea!

[Karl Towle]

I will point out that this great idea has limitations. It only works if the ID of the hole saw is VERY close to the size of the original hole. If you were to want to turn a 2-1/4" hole into a 3-1/8" hole for instance, You'll need to fabricate some 2-1/4" wood disks. How about if you want to move your hole 7/16" further up the panel? In these cases, clamping a scrap behind the panel, possibly extending the pilot drill and carefully measuring and center punching a new center may be the easiest technique to use. Just say'n.