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Discussion Topic:
Drilling holes in firewall
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ole_Bill |
12-17-2010 @ 5:02 PM
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New Member
Posts: 165
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I want to install a couple of guages in the firewall under the hood. The guages require a 2 5/16 hole. I have a holesaw that size and was planning to use it with my air drill. Now I donno - any help out there?
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Old Henry |
12-17-2010 @ 7:46 PM
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If the hole saw is for metal, why not do it? What is it you "donno" about?
Old Henry (The older I get, the better old looks.)
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carguy |
12-17-2010 @ 7:54 PM
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Maybe Ole_Bill is having second thoughts about putting huge 2 5/16" holes in his firewall. I sure as heck wouldn't do it. If I wanted instruments in the engine compartment I'd buy or make a bracket with the holes in it to hold the gauges and then bolt the bracket to the firewall.
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trjford8 |
12-17-2010 @ 8:09 PM
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A couple of 2 5/16ths holes in the firewall would not look to good to me. If you change your mind later they will be tough to fill. I would make some brackets that bolt to a head bolt or bolt to an existing hole in the firewall and mount the gauges to those brackets. The question I have is why you would want a gauge in the engine compartment where you can't see it? If you have an oil pressure gauge under the hood and you lose oil pressure, you won't notice you lost pressure until it's too late.
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Old Henry |
12-17-2010 @ 10:12 PM
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I can understand why one might want some gauges under the hood to be able to monitor some functions while working on the running engine and have seen gauges mounted ON fire walls but never IN firewalls. I agree with others that, if you want gauges under the hood, mount them ON the firewall, not IN it.
Old Henry (The older I get, the better old looks.)
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42wagon |
12-18-2010 @ 4:25 AM
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Bill For the reasons already listed I would find a way to mount a removable gauge board somewhere under the hood that didn't involve drilling any holes. You don't say how original or modified this vehicle already is but drilling big holes in the firewall sure ruins any originality it might have. Ted
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deuce_roadster |
12-18-2010 @ 8:49 AM
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Find a piece of tin that is large enough for your gauges, use your hole saw on that, then find some existing screws/bolts on your firewall to mount your new bracket and mount the guages in it. That way you can change your mind without making a lot of work for you or somebody else. I have welded up more holes in firewalls then I can count. Usually because people would go find a junkyard heater and drill a new set of holes to mount it. My 2 cents worth. This actually would be easier then cutting blind holes not knowing what you were about to ruin on the other side (like wiring).
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ole_Bill |
12-19-2010 @ 7:58 AM
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The part I "donno" about is that I have never tried to use a hole saw to cut thru metal. The hole saw I have, purchased from Northern Tool, says it is for wood and light metal. I definitely prefer the "set-in" look of firewall mounted guages vs panel mounted, but then don't want to screw up a perfect, newly painted firewall. The car is not, and never will be, original. It is a street performance driver that retains most of its original appearance. A wolf in sheep's clothing so to speak. I want guages under the hood because I see the need to monitor water temp and oil pressure while the car is parked, motor running, hood up. Locally, we have a lot of informal outdoor shows where that is a common practice. If you have ever been to one of the shows in Pidgeon Forge you know what I'm talking about.
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trjford8 |
12-19-2010 @ 9:20 AM
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Check with Moon Equipment Company in California(I think Santa Fe Springs) they have gauges that mount in the engine compartment that are attached to brackets on the motor.
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Stroker |
12-19-2010 @ 9:26 AM
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Well, Bill if you insist on doing it; I'd pitch your "hobby" hole saw, and buy a proper commercial metal saw, preferably with a fine-tooth Lenox bi-metal blade. Secondly, I'd use a slow turning, variable speed 3/8 minimum electric drill motor instead of an air drill. I'd tape off the area with masking tape, and then center-punch and drill a 3/16 inch "pilot hole" to ensure that the 1/4 inch hole saw pilot doesn't walk away from your chosen location. Drill slowly, so as not to overheat the saw or the paint on the firewall. I prefer to use pipe cutting fluid applied with a pistol oiler on the saw while cutting. Hole saws do not like to be turned fast, as it is hard for the teeth to dissipate heat. Just take it real slow, and you shouldn't even blister the paint around the hole.
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