Date sent: Thu, 17 Oct 1996 18:54:36 -0700 To: mstewart@m1.sprynet.com From: "Trenton R. Schoeb" Subject: FAQ OIL PRESSURE AND VACUUM GAUGE INSTALLATION (MAGNA) Brian Sydness PARTS Available from any auto performance shop: 2" AutoGage gauges, 25-$30 ea. Dashmount kit, $15 ea. Green "condoms" for lightbulbs, $2 1/8" MFF Tee, 90 degree, $3. Available from a hardware store: Rubber grommets (to seal from weather), $2 From Honda Vacuum joint, $5 PROCEDURE I chose oil and vacuum gauges because I had just completed the oil mod, and wanted to use a vacuum gauge to improve mileage. (Highest efficeincy = highest vacuum in each gear.) I never realized how little throttle movement affects vacuum. If I use the gauge consistently, I gain 4-5 mpg on the highway. The gauges came with an underdash bracket, which I didn't use. The dash mount kit has a base, a metal strap that clamps around the gauge, and a metal back cover. On both of the strap pieces, I straightened one side and bolted them together. You may have to reshape the clamp slighly. I would recommend just having it tack welded for more clearance and better looks. To install, remove both instrument rear covers and the plastic piece on the LCD display. Drill a small starter hole on both sides of the display, near the rear edge, and use a large sheet metal screw, maybe 5/16" in length, not too long. I'm not sure about the height; just locate the clamps, with gauges installed, and mark the holes. A 1/8" NPT tee worked fine for the oil pressure switch. Even though the thread on the switch is slightly different, it's close enough that it will screw together without damage or leaks, using teflon tape to seal the joints. (See ADAPTER.GIF.) The oil gauge kit comes with plastic tubing and compression fittings. I used heat shrink tubing to cover the white tubing, a real eyesore. For the vacuum gauge, I bought an extra vacuum fitting from Honda to read vacuum from the intake (same place that is used for carb synching). I also had to fabricate a simple restricter to keep the vacuum gauge from pulsating. Anyone that has synched carbs with vacuum gauges knows what I'm talking about. I used a 1/4" ID hex nut, drilled and tapped a suitable hole on one of the flat, and installed a 6 mm allen head screw. The vacuum line runs through the center, so that adjusting the allen screw in or out will dampen the pulsing. I tie-strapped it to the frame under the tank so that it is accessible without removing any covers. The backlighting is 12 VDC bulbs. Behind my headlight I found a brown unused connector and a green tee connector with an opening. The connectors provide power and ground when the ignition switch is on or in Park. Check the wiring diagram for your model. The supplied wiring isn't long enough, so you will have to solder in a long length with barrel connectors. Go to the nearest junkyard and grab a couple wires with connectors; they're universal. I also ordered extra green "rubbers" for the bulbs. They give off a nice green backlight that matches that of the stock instruments. After fitting all the parts and testing, I removed the back covers, straps, instrument covers, and plastic LCD cover. The stock covers were already scratched up, so I took the opportunity to repaint all the parts. I used off-the-shelf K-mart primer and gloss black spray paint. Sand, primer, wet sand with 600 grit, paint, wet sand again, paint, let dry, turn oven on to 125F, bake for 30 minutes, let cool, and add a thick coat of carnuba wax. The finished job looks great (see GAUGES.GIF), and I've had a lot of compliments and second looks from other riders thinking it was a factory option. The oil pressure gauge is great; no more worries. The vacuum reading is lower than that of a cage. 0 in Hg - WOT. 5 in Hg - Highway cruising. 5-10 in Hg - City, low speed, idle. 15-25 in Hg - High speed decels. The trick is to back off the throttle little at a time, so that vacuum increases, while maintaining your speed. I found that there is a considerable desrepency between required throttle opening and actual. An old fella, a friend of mine, showed me this tip. He used it quite a bit back when they had gas guzzling V-8 muscle cars.