Took the Cat into the garage, they tried to sort out the rear calipers but it appears that the pistons had seized. Replaced them and it worked perfectly. They tried to tune it but acknowledged that it was just too difficult and required specialist knowledge and pointed me at a local race-prep place. What they didn't tell me until I got there to pick it up was that they had fiddled so much that they couldn't even get it to start. 10 mins fiddling with the dizzy its running. 5 more minutes playing with the mixture and idle and its just about driveable, so much for going to the professionals :-)
Turns out that Sceptre Services prepare a mix of things for various race series but mainly focus on Ginettas. When I was there they had a pair of ginettas and an aston that does a UK-US series. Sounds like it was a pretty simple job once they'd realised that the idle jets were all different and replaced them.
Took the car for a blast afterwards, being carefull not to go beyond 4.5k rpm and not really suceeding, absolute revelation, idles nicely far fewer pops and bangs and noticeably faster than it was. Unfortunately a couple of miles down the road a fuse blew and the fuel pump cut out. Replacing the fuse didn't sort it and I had to get a tow home. Putting a 25A fuse in was ok but IMO a bit big for a fuel pump as a result I checked all the wiring and it appears that the pump does indeed draw anything up to 10A and there don't seem to be any other problems so put the fuse to the 20A that tiger recommend.
Checked up and discovered that I really should be running 34mm chokes rather than 32s. Once thats sorted and its been rolling roaded it should be stunning. According to Dave Andrews Jetting program the correct settings for the stage 2 tiger engine are:
| Carb Size | 40 DCOE |
| Choke Size | 34 |
| Main Jets | 140 |
| Emulsion Tubes | F9/F16/F2 |
| Air Correctors | 180 |
| Idle Jets | 55F9E |
| Pump Jets | 40E |
| Aux Venturis | 4.5 |
Jacked up the front of the car, which is not as easy when the normal jacking points are resting on the floor. Whipped off the sump and then the wishbone and took them up to Tiger. Met Paul there who was a little alarmed to say the least and he was straight on the phone to check to see if any other wishbones could be affected. Sue popped over from their other site and gave me a new sump, wishbone, upright, balljoint and every other part that could conceivably have been anywhere near the wishbone when it broke, all free of charge. As per usual they really went out of their way to help and once things are back in one piece I'll be popping up there to let them check out the other wishbone just in case.
Discovered that the car is running a little too hot for my liking, as a result bought the biggest fan that I could physically fit - a lovely pacet 1373 cu feet per minute of flow! Still running hot - hmm. Found a slight kink in the coolant hose at the manifold, not easily fixable and since it had to go an odd route I replaced it with some nice silicone 90° angled hoses and joined them up with copper plumbing pipe. Much nicer, at some point I may fit some nice chrome pipe instead, but for now the copper is just fine.
Also ordered some new chokes - 34mm since I knew I was going to have to go up a size or two at the rolling road. Fitted them, car was running far too lean, so much so that I had to fit the old ones back again.
Still running rather hot. Sounds like the root cause is lack of airflow (partly down to the mesh) and under-specced radiator (given the state of tune). Time to change the mesh for a bigger one and then think about a new ali rad.
Last time I was at tiger Paul noticed that I was missing a bolt through the steering shaft, it was locked solid so we left it but it has given me a slightly uneasy feeling ever since. Finally got round to fixing it, and given the solidity of it I don't think i really needed to bother but I can sleep rather sounder now knowing that it is done.
Had my ac22 upgraded to the datalogging version the ap22 and have been doing a few 0-60 runs along a deserted piece of country road near my house. With the ac22 I just knew that my times were pretty poor 8-9s, with the ap22 I've been able to graph it up in excel and work out where I'm going wrong. The first run after checking the graph I was doing 7.8s, next time round 7.3 and I've now found a couple more places that I can improve and it looks like 6.5 is doable. The main things I'm changing now are to change earlier in 1st at about 25mph and then to go all the way through to 60 in 2nd and skip the change to 3rd. It means going through to 6500rpm - peak power is at 5500rpm but on balance is better than the .5s lost in the change. The other thing that looks interesting is skipping first altogether and just using 2nd. On paper it should be good for 6.5s just the same as using 1st but should be a lot more repeatable. Will have to try it out.
Fitted new magnet to the wheel to re-enable the digital speedo, should be interesting to see how accurate the mechanical one is now, it used to be miles out but It appears to be reasonably accurate from what I can see.
Another job that had needed doing for some time was to fix the coolant hoses to iron out some of the kinks and to alleviate some of the cooling issues that I'd been having. I had originally used standard hoses and used some overbraiding to make it look neater, unfortunately there were some slight kinks in the system which reduced the flow. Solution number one was to put some 90°angles in and join them up with copper plumbing pipe. This was neater but the flow was still restricted slightly and wasn't as aesthetically pleasing as it could be. Purchase of one pipe bender later and I'm away.
The new plumbing solution was to take standard 15mm copper plumbing tube and to bend it to
shape, the frst pipe being the one from the water pump to manifold, that being the one with
the most influence on cooling, the one with the most convoluted path and the most awkward
access. 90° silicone hoses on either end of the pipe, turning under the exhaust
headers, around the back of the block and then into the manifold. The second pipe to
do was the expansion tank one which is in my opinion the most important one as far as
looks go, a piece of silicone hose as a joiner, a loop over the top of the rocker and
then along parallel to the carbs.
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Still to come is a new pipe from the bottom of the expansion tank to the rad, unfortunately
it requires some reducing silicone hoses which I don't yet have so will have to wait.
Mixing with 600bhp Supras, Elises and a load of Caterhams the Tiger was holding up very well, with a 80m trip each way I couldn't risk anything but in the end the car behaved impeccably. Despite me still not being 100% happy with the brakes and the superior handling of the Caterhams I was keeping up - despite my novice driving. As you can see from the pictures below the Tiger has very little body-roll compared to the Caterhams and the A539s are very grippy and progressive for road tyres.
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As a result of the trackday about the only thing I would change on the car would be the brakes, I have a sneaking suspicion that the master cylinder isn't big enough for discs all round so on would go a Stuart Taylor adjustable pedal box and the brake lines would be swapped for aeroquips. Apart from that maybe a little more power...
The journey home was pretty miserable in the cold and dark but the engine really does seem to have loosened up nicely, it seems far keener and have a hell of a lot more go. Perhaps I should get hold of some 45s and that vernier pulley. More pictures from bentwaters are here.
In summary I would thoroughly recommend the trackdays which are available from bookatrack the instruction is also good value at £20.
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