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Tripower carb mystery

December 1 2017 at 11:13 PM
Martin  (Login 357M)
Members

I noticed the center carb has a much weaker pump shot than the end carbs. I am assuming they should all be the same as they are all 30 cc pumps. If I measure the movement at the pump end of the lever, I get about 1/16" on the center carb and 3/16" on the end carbs. However, if I swap the lever and the plastic cam with one of the end carbs, the lever movement is still 1/16" for the center and 3/16" for the end carb. I don't see any reason for the disparity. I tried several cams and levers from other Holleys with no change. The distance from the throttle shaft to the edge of the plastic cam is the same on both as well.

Holley sells a kit with different cams. I'm sure there is one that would help but I would rather fix the underlying problem. Anyone encounter this problem?

 
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AuthorReply

TorinoBP88
(Login TorinoBP88)
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No expert, but

December 2 2017, 12:02 AM 

I observe most tri power set ups have bigger carbs on on end, and prob ne d now gas.

Also squirters may be a different No.

And rate of pump can effect gas flow.

Ball check weight inside cards accell circuit could be different weight, or corroded causing a restriction.


 
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Martin
(Login 357M)
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Re: No expert, but

December 2 2017, 6:22 AM 

Well, I think the small amount of fuel that comes out is due to the minimal movement in the lever. I get a good pump shot if I push down directly on the accel pump arm. Thanks for the reply, all good things to check

 
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Mark
(Login 66gt500)
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Pump shot

December 2 2017, 10:30 AM 

The check valve in the bowl is probably bypassing some, so some of the pump shot goes back into the bowl
My 427FE Is Going My 65 Fastback!
DriftFox
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Martin
(Login 357M)
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Re: Pump shot

December 2 2017, 11:07 AM 

The lever itself is not moving enough. The pump and everything between the pump and the venturi are out of the equation. Yet replacing the cam and lever with ones from a known good carb doesn't help.

 
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Jeffrey R.
(Login 52Ford390)
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Are the butterflys open the same amount ?

December 2 2017, 4:40 PM 

If the center carb. is farther open than the secondary the pump lever may have started up the pump cam ramp reducing the overall lever travel.
JJR


 
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Martin
(Login 357M)
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Re: Are the butterflys open the same amount ?

December 3 2017, 9:40 PM 

I closed it all the way and remeasured. No change. Good idea though

 
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Torbjörn Kristiansson
(Login Tobbemek)
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Pump cam mounting screw holes

December 5 2017, 3:40 AM 


I would take a closer look att the pump cam mounting screw holes position on the throttleshafts to see if they are in the exactly same position on the center carb as outer carbs. Like position #1 gets a different ramp on the pump cam than position #2 will.

 
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