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Old 15th February 2007, 07:22 PM   #1 (permalink)
raven1
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throttle cable issues

I know this has been discussed before but thought I might save someone a lot of headaches. I changed carbs from a holley hp with vacumn secondarys to a mighty Demon with mechanical secondarys and found I could not open the throttle all the way. The Demon required a lot more pull to fully engage the secondarys and the set up that I had would not exert enough pressure through the cable and give the desired throttle. The carb was mounted in the traditional way with the carb linkage requiring a pull from the rear of the engine. After hours of trying this and that I discovered I could reverse the carb and have the cable pull directly on the carb linkage with out a secondary set of linkage. In my case the fuel line was very easy to move to the other side. I was able to shorten my cable by 3 feet.
The end result is a throttle that is far superior in ease of operation and more linear response.
jerry gt40p2124
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Old 16th February 2007, 10:00 PM   #2 (permalink)
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Re: throttle cable issues

Quote:
Originally Posted by raven1
The carb was mounted in the traditional way with the carb linkage requiring a pull from the rear of the engine.
That strikes me as quite odd. Why would the throttle cable be routed all the way around to pull from the wrong direction?

All I really know are Panteras, and they mount the carb in the traditional orientation, with the cable coming up through the firewall, up the front of the motor, and pulling from the front. Seems like a no-brainer to me?
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Old 16th February 2007, 10:49 PM   #3 (permalink)
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Re: throttle cable issues

Jerry;
You didn't say what type of cable you were using, and I can tell you that it will make a big difference in the quality of the cable. I have used cable throttles that push on the carb linkage...sounds awful backwards, but a good quality cable will do this with minimum of friction. A good quality cable should be really smooth to operate, and do it with bends minimally affecting the action. The last one we did actually returned to idle with just the spring supplied on the carb throttle shaft, but we added a spring to be safe. Also this puts a lot less bearing on the throttle shaft on the carb(s) which can wear out and cause hard to find vacuum leaks. Hope this helps.
Cheers
Phil
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Old 17th February 2007, 11:24 AM   #4 (permalink)
raven1
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Re: throttle cable issues

I suppose I did not explain myself very well. When I said the carb was mounted in the traditonal manner, I was referring to a front engine car with the throttle going through the firewall and pulling the linkage. When you do this on a midengine car the carb needs to be reversed and the cable pulls directly on the carb linkage.
Jerry gt402124
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Old 17th February 2007, 01:08 PM   #5 (permalink)
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Re: throttle cable issues

Jerry:

What is done on the Pantera that Mike Drew was referencing is that the cable attachment point for the throttle cable is moved to below the centerline of the carb throttle shaft in lieu of above like the "conventional" arrangement that you refer. Many carbs have linkage attachment points that can be either above or below the shaft allowing linkage to either push or pull from either front or back of motor. If yours doesn't you can fabricate a simple bracket that attaches to the carb that allows the cable to pull from the front without reversing the carb. It probably doesn't matter with most manifolds but there are some like the Offenhauser dual plane manifolds that the carb orientation if very important.
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Old 18th February 2007, 09:39 PM   #6 (permalink)
raven1
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Re: throttle cable issues

Mike, Thank you very much for the explanation, at the time I was having this trouble my panterra was not at my home and I could not look at it for guidance, however it is home now and I looked at it and see exactly what you mean, however the edlebrock manifold on my side oiler has intake runners too high for a below centerline cable connection, the pivot arm would hit the runners.
So far reversing the carb has had no adverse effects and the linkage is great.
Mike, I don't see your name on the list for the Branson ssr event there should be some great road trips around Branson. Have you installed your engine& transaxle yet? If your car is not ready you can drive my cobra & I'll drive the gt40.
Jerry gt40p2124
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Old 19th February 2007, 06:15 AM   #7 (permalink)
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Re: throttle cable issues

Jerry:

My car was supposed to arrive in port yesterday. I hope Dennis gets it to his place some time this week. I'd just like to see some pictures of it. Dennis said that it was the first right hand drive right sill shift car in the US. It will be several weeks before I can go and pick it up. Your offer to use your Cobra for the event is a very kind one and I appreciate your offer. I've always been very reluntant to drive someone elses car for fear of breaking something. Thanks again. Hopefully we can get together soon and talk cars.

Mike gt40p2165
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Old 19th February 2007, 06:46 PM   #8 (permalink)
raven1
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Re: throttle cable issues

Mike, I am sorry to hear that you don't have your car I thought it was due last month. If I haven't broke my cobra it can be broken the little 392 is indestructable and you are welcome to drive it.
Jerry
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