85 Supra Comp Speedometer Questions

[MarbleFalls]

Whats the purpose of having two speedometers on the boat?

What are the two cylinders at the transom before the lines go into the pickups and what are their purposes?

Is this a standard tubing I can "pickup" at Home Depot?

When rebuilding a boat, do people always go back with 2 speedos?

Thanks in advance for your input! Happy 4th to everyone!!

[mlaosa]

The purpose for two speedos is for competition skiing to help be accurate with speed. The two "tubes" at back of boat are pitot tubes used to make the speedos work. I'd look online for pitot tubing. And no you don't have to have two speedos. Btw saw your boat on Craigslist other day. That guy was giving that thing away!

[MarbleFalls]

The purpose for two speedos is for competition skiing to help be accurate with speed. The two "tubes" at back of boat are pitot tubes used to make the speedos work. I'd look online for pitot tubing. And no you don't have to have two speedos. Btw saw your boat on Craigslist other day. That guy was giving that thing away!

Thanks for the response Mlaosa! He gave it away most likely knowing what all was actually wrong with it. Already replaced the head gaskets, did the valve job myself, rebuilt the carb, plugs, wires, cap, points, rotor. Removed the tank and flushed it, full of water/gas. Rebuilt transom and beefing up the swim platform. Removed all of the foam/water and contemplating whether to sacrifice $200 in decking, PL and carpet to gain 3-4 months of usage before summer is over. Decisions, Decisions ....

[Jetlink]

Just do it right the first time and be happy with a properly functioning boat for next season.

[SUPRA_ALLEGRO_LANE]

Marblefalls, will you be replacing your Lights and Blower switches?

[MarbleFalls]

Marblefalls, will you be replacing your Lights and Blower switches?

I'm not sure, what makes you ask?

[SUPRA_ALLEGRO_LANE]

I would be interested in buying all the black pull knobs. They look to be originals. I'm trying to restore my Allegro back to stock.

[Poorhouse]

I would be interested in buying all the black pull knobs. They look to be originals. I'm trying to restore my Allegro back to stock.


I am interested in the bezel around the ignition switch.

Only piece missing on the interior of my boat.

[MarbleFalls]

I am interested in the bezel around the ignition switch.

Only piece missing on the interior of my boat.

I appreciate the interest guys, but I'm too far into the project now to part out.

[NorCalPR]

Whats the purpose of having two speedometers on the boat?

What are the two cylinders at the transom before the lines go into the pickups and what are their purposes?

Is this a standard tubing I can "pickup" at Home Depot?

When rebuilding a boat, do people always go back with 2 speedos?

Thanks in advance for your input! Happy 4th to everyone!!
In case one fails. Theyre prone to clogging.

The metal cyl on the back transom are to convert the water pressure to air pressure. The speedo unit on the dash should only see air pressure, and no water pressure.

Im sure you could get some vac hose tubing at a auto parts store.

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[Poorhouse]

I appreciate the interest guys, but I'm too far into the project now to part out.

Glad to see you save it.

I posted my comment because you were considering replacing the switches. If you do that keep me in mind.

Thanks.

[92SupraComp]

Be careful if you touch those speedometers. They are precision instruments. If they both work, and work well, they can fetch a good price. One of our is broken and to have it repaired is very expensive.

When GPS technology really came under way in the 90s and early 2000s Air Guide couldn't compete and lost out quick.

[MarbleFalls]

Be careful if you touch those speedometers. They are precision instruments. If they both work, and work well, they can fetch a good price. One of our is broken and to have it repaired is very expensive.

When GPS technology really came under way in the 90s and early 2000s Air Guide couldn't compete and lost out quick.

Thanks for the tip on the speedos. The boat had been sitting up for at least 5 years if not more when I purchased. Bad part is I don't know if they are working yet or not. Guess I'll find out in about another week or so when i finish the transom, stringer and deck.

[MarbleFalls]

In case one fails. Theyre prone to clogging.

The metal cyl on the back transom are to convert the water pressure to air pressure. The speedo unit on the dash should only see air pressure, and no water pressure.

Im sure you could get some vac hose tubing at a auto parts store.

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Those were the answers I was looking for, thanks NorCalPR !!

[NorCalPR]

Thanks for the tip on the speedos. The boat had been sitting up for at least 5 years if not more when I purchased. Bad part is I don't know if they are working yet or not. Guess I'll find out in about another week or so when i finish the transom, stringer and deck.
You can test it with air pressure.

1.5 psi = 10 mph
2 psi = 12 mph (Typical pressure produced by a set of young health lungs.)
6 psi = 20 mph
13 psi = 30 mph
23 psi = 40 mph
52 psi = 60 mph



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[SquamInboards]

Don't know if I've shared this before but you can get parts for these speedometers now. Not cheap but they look like the real deal, even replacement lenses which were impossible to find a few years ago.

http://www.classicboatwork.com/classicparts/gauges/airguide/agr/agr.html

[Fuscanini]

I have 2 speedos on my '87 Salt. One is 5mph faster than the other. Can I assume the higher speed is correct and the lower speed is incorrect and has clogged hosing?

[NorCalPR]

I have 2 speedos on my '87 Salt. One is 5mph faster than the other. Can I assume the higher speed is correct and the lower speed is incorrect and has clogged hosing?
Usually if theyre clogged theyre just sluggish.

If there an adjustment dial? If so, assume neither are correct and verify it with a gps.

When I had 2, i set one calibrated at 10 mph, one was calibrated at 22mph.

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