Accelerator Cable for Dual Carbs ? Options

[cary]

In putting Mark's engine back in and replacing the broken accelerator cable. It seems the cable isn't quite long enough to work/fit correctly. In the FI arrangement the cable crosses the engine at 45 degrees. In dual carbs it needs to come at the bar at 90 degrees. Which pulls the bowden out of the firewall. Which will allow water down the cable tube.

What have others done to work around this ?

[Darren C]

Thanks jd, much appreciated. I waste a lot of my life in FMEA meetings only to walk out cynical about the rating value, which can, like statistics be manipulated for the goal at hand by the strongest players in the room. However I grant you, it’s a good communication device for getting messages across and translating engineer speak to bean counters.
Fluidic/Thermal controls engineer..great, I love thermodynamics and HSD loops!
What’s interesting is your comment on aftermarket or niche low volume manufacture occurrence rating. At R-R the best jobs are in Bespoke where low volume can mean just 1. We obviously make more than 1 of things, even though only one may be sold. This strategy makes FMEA very interesting. Only last week the first customer Black Edition (very low volume) Wraith’s were finished. These have an interesting wheel design (interesting for a Rolls-Royce that is) because it’s made of carbon fibre. I can’t say too much on the internet, but the development was troublesome in combination with the weight loads that could theoretically be placed on the wheel from the 3 ton car at 155 miles per hour +, versus the designers brief and aesthetic. Suffice to say the whole engineering ethos behind the choice of carbon fibre as a construction material fell to the engineering practicality and safety resulting in a carbon fibre wheel that’s actually heavier than the standard Wraith alloy. This is a good example of what I was trying to express about “all good intention” by the throttle linkage makers.
I know most responses to my posts in this thread have rightly challenged my credibility and experience, and I’ve said a few things to try and substantiate them, but something else that is worthy is my own car collection.
This runs from pre second world war to current cars. I have a collection of finished restored cars (my life’s work) and cars stacking up to be restored. These kinda chart and document the history of car evolution. This evening after work (and working on my 14) I thought I’d share some in relation to linkages which people think I don’t have any experience with.
From Edwardian times throttle linkages have evolved from large heavy solid metal bars, thru dainty rods, on to wire cables and now FBW.
I have cars with all of these examples that I’ve restored. The very early cars were exceptionally crude but very ingeniously and beautifully engineered. Throttles didn’t always start off under your foot, they were on hand wheels (like a steam train), hand pull levers, and attached to the most odd things in the cabin. Foot pedal accelerators started to become the norm very early in the 20th century (although they first appeared before 1900) each car manufacturer had their own idea. What was common however is the ingenious methods to connect their throttles to the carburettor.
For a time even some manufacturers had part throttle on the floor as a pedal, idle throttles on the steering wheel and choke/start throttles on the dash!
Basically 3 sets of mechanical linkages to one single carb, each pulling on a different lever via the most elaborate “watchmakers” engineering. The simplest ball joint would have phosphor bronze cup bushes each side with tension springs inside the ball joint to give fluidic contacts between ball and cup, take up wear over time and be ever reliable. The basic bell cranks were cast in the finest steels, to Victorian aesthetic designs with white metal or bronze bearings, some even incorporating automated oil feed systems built into the car.
Not only were throttles done this way, timing advance was too. In tonights pictures I’ve taken, I chose an early 30’s car from my collection so that you might recognise some basic parts. This is when distributors started to look like what you’d recognise as distributors and so on. In the early days of motoring there were no vacuum advance or centrifugal advance of the ignition timing, so you had to twist the distributor by hand, while driving. Some manufacturers like Bugatti had the distributor poke through the dashboard at you to make it easy to adjust your timing, others created more linkages for you to push and pull or slide when you were driving. Again different manufacturers chose different methods it wasn’t standardised, but all involved mechanical linkage.
Some even back in the 1920’s had ride control (adjustable suspension) via adjustment of oil pressure to the dampers (shocks if you will). Guess what, more linkages around the car.
These are days before hydraulic brakes, so yet more rods and linkages across the chassis with clever mechanical transitions to take into account suspension movement and steering while using brake rods. The car I’ve chosen in the photo actually has another set of rod linkages for a brake servo which works of a dedicated clutch plate on the side of the gearbox at 90 degrees to the motor drive clutch. In certain gears this mechnically engages with the footbrake lever to a collection of additional servo brake rods giving greater mechanical force to the front brake drums.
So all in all this car is linkage-tastic, you might say. And boy was it a challenge to dismantle, restore and set back up as a result. I learnt a hell of a lot on this car alone.
Here’s some of the basic linkage controls on the steering wheel. You can also just see the carb start lever on the dash behind the throttle open position on the wheel.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i265.photobucket.com-18255-1463170009.1.jpg)

The way it works is with a set of ever decreasing diameter tubes within tubes all the way down the steering column.
The largest tube is the steering itself which has the worm gear attached in the steering box at the bottom. The other tubes run trough oil seals and bearings to exit out the bottom of the steering box in the engine bay.
These have levers attached that connect to numerous control rod linkages that go off in this case to….the top one turns the distributor for ignition timing, the next one goes to a linkage and bellcrank which actually passes right through the engine block between cylinders 3 & 4 in this straight 6 to reach the throttle lever on the carb. The final link goes off to connect to the 4 dampers one on each axle which stiffen or soften the ride.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i265.photobucket.com-18255-1463170009.2.jpg)

There are also two separate rod linkages to this car’s carb that run from the foot accelerator and another from the dashboard start throttle.
All in all you can imagine it’s a real handful to drive this thing.
The luxury of having so many classic cars is that you see and get to work on all sorts of set ups, you see how things evolved and developed (good & bad) and you connect with the people and time in which they were made.
I also like to think that in some way also it allows you to make constructive and experienced comment on things when you have an extraordinary experience and knowledge of the subject matter, its history and development within the market place.