GTC horns

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Steve Meltzer
Posts: 982
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

GTC horns

Post by Steve Meltzer »

Finally closing in on the engine R&R on my 330 GTC (too bad i don't get paid by the hour!). Decided to paint the horn trumpets since I'd run out of stuff to do (not) and they were, well, right there beggin' for a fresh coat of paint. Of course, they worked great when I removed them. The (compressor) horn motor works great (tested on a Hella trummpet i had in my stash), but not either of the GTC trumpets. When i painted the trumpets i unscrewed them from their diaphragm bases, painted and replaced, at, what I thought was the same depth. I took one of the bases apart, as you can see in the photos, but blowing compressed air in the orifice just results in air exiting the trumpet....no sound. (other than me swearing) Could I be using too much compressed air? (please, no jokes about my XS of hot air...I get enough from Mrs. M.) I think this has to do with the movement of the diaphragm. Or not. thanx steve
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steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
John Vardanian
Posts: 1906
Joined: Wed Sep 04, 2002 12:13 am
Location: San Francisco Area

Re: GTC horns

Post by John Vardanian »

Steve, the trumpets need to be tuned with the car's battery power, with both trumpets connected to the compressor. Loosen the collar nut of one of the trumpets and screw it in till it gently bottoms out. Then, with the compressor running, unscrew it until you achieve the loudest/clearest tone. Then do the same to the other. Once both trumpets sound pretty well, you may need to screw/unscrew both or either trumpets slightly (while the compressor is running) for the right tone. Hope this helps.

john
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Steve Meltzer
Posts: 982
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: GTC horns

Post by Steve Meltzer »

So, there is no reason that they shouldn't work. Right? Can they be bench tested, not for fine tuning, but just to see if they work as they should? thanx. s
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
Steve Meltzer
Posts: 982
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: GTC horns

Post by Steve Meltzer »

OK, on the bench with my compressor providing the ooomph, i got them to work by screwing the trumpet much further down on the diaphragm than I had previously. Now, I can install and fine tune (couldn't resist that easy pun). Thanx John for pointing me in the right direction. s
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
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tyang
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Location: New York
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Re: GTC horns

Post by tyang »

Hi Steve,

You probably got it by now, but a couple of points to consider for others doing the same thing.

The diaphragms can easily get cut if the horns are screwed in too tight. You can buy thin brass shim stock from McMaster Carr to make new ones.

Make sure the air compressor is well oiled as the vanes inside work better with lubrication. If you have the plastic compressor cover, the GTC compressor rarely gets oiled.

Like John said, the horns balance with each other, so the tuning of each trumpet affect the other one.

I often put on a pair of ear muffs, and remotely operate the horn as I tune the trumpets. You can run a wire from the bottom of the steering column contact to ground to operate the horn from the front of the car.

Good luck!

Tom
'63 330 America #5053
Steve Meltzer
Posts: 982
Joined: Mon Sep 06, 2004 10:31 am
Location: with Barney the Beagle boy and Enzo 8995

Re: GTC horns

Post by Steve Meltzer »

Tom, thanx again for the tips. Hope to get out there to finish this part of the project this AM. (sorry we didn't make the party in Monterey...the weekend there, tho' fun, has gotten to be outrageously expensive, so we voted with our Visa card. For us, your party and the chance to see old friends and make new ones, was the only "have to do" of the weekend.) s
steve meltzer,
"I've spent all of my money on wine, a beautiful woman, and stunning cars. Then, squandered the rest."
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