HR Carb issue

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Kurt Bogerman
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Vintage Karting items owned: 1964(?) Rupp Grand Prix, MC 90, Safari Gearbox.
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Location: Harrisburg, PA

Re: HR Carb issue

Post by Kurt Bogerman » Mon Aug 27, 2018 7:21 pm

Oops! My mistake. I was looking in the 90A column :oops: . Carry on!

Rob Voska
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Re: HR Carb issue

Post by Rob Voska » Tue Aug 28, 2018 4:27 pm

I'm not going to look up all these odd carb numbers.

1. Were these external pulse line carbs when new?

2. You have yet to run this under load correct?

al peckenpaugh
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Vintage Karting items owned: 3 Rupp 1 Red Devil
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Re: HR Carb issue

Post by al peckenpaugh » Tue Aug 28, 2018 9:18 pm

1 Yes, they were external pulse. Pulse holes in diaphragm plate blocked. Pulse hole clear from mounting flange to plates. They suck fuel..
2 Yes, not run under load. I've been thinking the same thing. On the track there is no place you would go from wide open throttle to sustained idle.. I think if the throttle were "blipped" a few times coming in the pits it would continue to idle...
I'm going to stick new ball valves in them and see how they act.

Rob Voska
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Re: HR Carb issue

Post by Rob Voska » Tue Aug 28, 2018 10:39 pm

Just guessing but I doubt if your plates are vented to atmosphere from the top side of the diaphragm.
Not relieving the pressure it shoves the fuel into the venturi where it floods the engine.


It's late so doing this from memory. If you look close in the plate on top of the diaphragm there will be a small brass plug from that side that vents to atmosphere. Take that out & reset all the stuff you changed is where I would start.

al peckenpaugh
Posts: 19
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Vintage Karting items owned: 3 Rupp 1 Red Devil
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Re: HR Carb issue

Post by al peckenpaugh » Wed Aug 29, 2018 8:41 am

I've checked and rechecked the vent because there is a passage between two holes in the plate that would provide the vent. Must be set up so plate could be used on different models of the carb. On mine one hole gets blocked by the gasket, the other vents. But, I'll go check again...... That makes sense if the ball valves are actually good. There's no brass plugs.

al peckenpaugh
Posts: 19
Joined: Sun Jul 29, 2012 8:22 pm
Vintage Karting items owned: 3 Rupp 1 Red Devil
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Re: HR Carb issue

Post by al peckenpaugh » Wed Aug 29, 2018 6:30 pm

Yeh, Rob, Back of diaphragm is vented to atmosphere.

al peckenpaugh
Posts: 19
Joined: Sun Jul 29, 2012 8:22 pm
Vintage Karting items owned: 3 Rupp 1 Red Devil
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Re: HR Carb issue

Post by al peckenpaugh » Mon Sep 17, 2018 6:33 pm

Problem solved...
Trading the two HR's for two HL's did the trick...
I don't know why those HR's acted like that. I have them working on other engines..... ???

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