More Modifications. Major Step Backwards.

October 8th 2013

So, I took the car to my friends's farm and ran around for an hour or do. Eventually got the Weber to run pretty well and we got up every gradient we tried (funny how you can do that, unless it's actually on a Hill in competition).
However the main problem with using a Weber became obvious.
If you climb a very steep hill the carb (as well as the car) tilts and the fuel level in the carb become low at the front and deep at the back. That's where the emulsion tube is. That's the pipe through which all the fuel going to the jets passes and if it's too deep it over-richens the mixture, Badly.

So, in summary, It's great except when you go up a steep hill.

Eeeek! Not much good then, as the premise is that we climb steep hills.


Back to the beginning, At home I ripped off the Weber and refitted the SU lookey-likey. The thing I now needed to do was develop a better progressive throttle linkage to give me much more low-speed control.

Whilst laying in bed I dreamed up a two lever, two-stage mechanism. Whilst I could see it working in my mind's-eye I had to work out how that was happening. It didn't take long to make. The rods are old wheel spokes. I had to make a new bracket to hold it all together. Tried it out and "Wow" it works.

OK. So just how does it work? The cable pulls the top-hung lever. That pulls both rods, but the top one is the first to pull on the throttle lever (on the right). As the top-hung lever moves the bottom rod takes over and whips the throttle lever over. So we have slow first stage and quick second stage. Ideal.

I hope that explains it.

Of course I now have a Weber-shaped hole in the bonnet. I have some red gaffer tape which is an excellent match for the car colour so that is what I stuck over the hole. Didn't look too bad, actually.



On to the next event. The site near to Sedbergh is amongst the trees with no respite from the steep terrain so that even getting between Hills (the term for each test) is a trial in itself. The only way to get from Hill 4 to Hill 5 is to wait until no-one is running on Hill 3 and go up the track that is part of that test. Ian suggested a bottle of wine for just reaching the start of the Hills. No-one responded.

The new throttle mechanism worked well with regard to progressive control.

As things heated up the top rod became a bit sticky in the hole I had made. Although I had elongated the hole to allow for the change of angle of the lever it was still binding a touch. I need to relieve that hole and possibly fit a small spring to ensure the lever returns to the throttle stop point. Or, I may alter the main throttle return springs to give more pull, but that will effect full throttle resistance as well.
I made a water jacket for the manifold to help with possible icing-up problems, but haven't plumbed it in yet.

The main problem was the faster tickover caused by the rod binding, but that also hid a developing air leak on the carb manifold. This may have exacerbated the overheating. It was easily solved by nipping up the bolts up a touch. I have used a paper gasket, but may get an "O" ring mount so that sealing is easier to achieve.
The overheating was par for the trials site, which is very steep, so even running between Hills doesn't give any respite to the motor.

I was quite surprised that 3 people came up to me during the day and said they had been following the progress of the throttle saga on my Youtube channel. 

Frightening. I have stalkers

The starter motor stopped working. I initially thought it had jammed, as I heard a clunk. But Ian pointed out there was noise noise at all when I pressed the starter button so it looked to be electrical. The problem occurred quite high up on the site so we could start by bumping off down hill. However it meant that we couldn't really afford to switch the engine off, but we needed to to let it cool between Hills. Bit of a bind really.
After Ian fell and hurt his knee whilst pushing the car, a picture taken by Glen shows that he has developed a death-stare (which I cannot see as I am concentrating on other things). 

At least he has a new red hat (he lost the old one last time). Happily, he fell face forward. If that is the correct sentiment.

  We eventually found that the undergrowth had pulled the solenoid wire off. I say eventually because it wasn't visible except from below and crawling about in mud isn't high on my priority list for a Sunday afternoon. We'd checked all the other wires as far back as the starter button.

The actual driving was a mixed bag. Some hills were a disaster with uphill, left turns proving difficult. Some hills were great and we scored 2s, 1s and a clear (12 is bad, 0 is good).
Observations from marshals led us to suspect the left rear brake isn't working properly. I'd just checked the brakes and put new pads in. This could be part of the problem as you don't get the chance to bed them in like you would on a road car. Someone suggested jacking the car up and running in gear with the brakes dragging to wear down any high spots. Seems a cheap and possibly successful way to bed them in.
We made better progress thereafter by treating the left fiddle-brake-turns as a do-or-die, pull as hard-as-humanly-possible event. 
 I'd already decided that we may try alternative methods on subsequent runs to try and get the best technique. The trouble with this is that by definition some runs won't be as good as others. Still, that's how you learn. I'm thinking that I am still used to the under-powered Imp engine so when we have grip I make the most of it and probably end up going too fast. I also think that I need to get the hang of easing out of the throttle for awkward surfaces to avoid losing grip.
However we did better than we usually do, especially in getting past the bottom of the hills. 

Next post will be about some detail work on the brakes and inlet manifold.