Follow along as I build a high performance 914 engine
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:
(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:
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:
(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!
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:
Here it is once I've machined it out of two pieces of aluminum. Again, I'll be using HTS2000 to bond them together:
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:
And here is the "slave" (right) side:
And here's the whole system together:
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:
|All pictures and text copyright 2008|