Building Cable Throttle Linkage

I originally had a cross-bar throttle linkage... I was never very happy with that - primarily because of the play in all of the components and because of the angle changes between components as it was actuated. I believe this is one of the reasons I was never that happy with the engine's performance before. It had a propensity to open the carbs at different rates and different amounts. I ordered CB performance's "hex-bar linkage", but I quickly felt it would have a lot of the same problems.

In a forum thread, I came across Jake Raby's soon-to-be-release "Accu-link" cable actuated concept. Instead of waiting a few months for that to become available, I decided to build my own. I bought some cables and had some aluminum laying around. First step, make some pulleys:

Machining throttle cable pulley for Porsche 914 engine

 

(Actually, the real first step was to take some careful measurements of the gas pedal throw and the accelerator cable movement - then do some math... but I have no pictures of that.) Here's the first pulley - the "master" which will have 2 cables attaching to it:

Throttle cable pulley for Porsche 914 engine

 

Now that both pulleys are made, I had to make the flats in the hole for the carburetor shaft. Normally, this would be done by drilling an undersized hole and using a broach tool. However, I managed to get great results by making a "shaft like plug" - a steel rod with the right diameter and flat sizes - putting that in the hole and then using HTS2000 aluminum brazing rod to fill in the empty spaces:

Throttle cable pulleys for Porsche 914 engine

 

(Note the pulley on the right has a hole for the throttle return spring - because of the orientation of the carbs, the other side has the spring at the opposite end from the pulley.) Now it's time for a test fit. It's looking good!

Master throttle pulley on Porsche 914 engine

 

Brackets will be needed to hold the cables. I made templates out of paper so I could figure out how to make it using the stock sizes I had:

Paper template of throttle cable bracket for a Porsche 914 engine

 

Here it is once I've machined it out of two pieces of aluminum. Again, I'll be using HTS2000 to bond them together:

Throttle cable bracket for Porsche 914 engine

 

I picked up a few M10 bolts to use as my adjusters. One of the most time consuming jobs was gun-drilling these. Here's the completed "master" (left) side:

Throttle cable linkage on master carb on Porsche 914 engine

 

And here is the "slave" (right) side:

Throttle cable linkage on slave carb on a Porsche 914 engine

 

And here's the whole system together:

Throttle cable linkage on Porsche 914 engine

 

It operates really smoothly, is easy adjust and was cheap to make! Although I spent about 10 hours on it, and I already had the aluminum from other projects, I only spent about $5! Here's a video of it in action:

 

I've learned that Tangerine Racing, a shop that specializes in 914s in Connecticut, has a cable actuated throttle linkage similar to this one for sale here.

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All pictures and text copyright 2008