Dutton Kit Cars and their owners
Ok, you probably read in my technical question about me breaking the pump injector in the carb, and having to hike down to Fife to pick up a replacement carb to rob the part from.
I'm delighted to report that it has been worth it!
Took the new (still old and used, but new to me) carb apart and retrieved the pump injector. It's in great nick - didn't even need to free it off or de-gunk it. Carb in general was pretty good nick, much better than mine at the outset. However, I decided to persevere with my own one, having spent half a can of carb cleaner and lots of PSI's of air getting it sorted out.
So I stick the carb back together and shove it onto the engine. As before, it runs no problem while on the choke and then throws in the towel as soon as the choke starts to close. Bugger. Had hoped the second phase of de-gunking would have sorted it. Oh well. So, just in case it's something else, I put on new plugs and leads to rule those out. Give the starter button a speculative jab, and get some grinding noises briefly, then nothing.
So, more fault finding. I spot that I've trapped the starter motor wiring between the solenoid base and the engine mount when re-installling it. I prop the engine up on a jack and liberate it. It doesn't appear damaged but the solenoid wire has been spliced on a spade connector, and the wire has pulled out of the crimp. Hadn't even been done using a ratchet crimper, so I'm not surprised. I remake the connection with a tube connector and a ratchet crimper. I hit the starter again.
Ok, I start working back, and find a massive clump of tape on one of the relevant wires. I cut this back and find another crimp, out of which the wire just drops. Again, I redo it with a tube and ratchet crimper. Paw the starter button again.
Running out of ideas. Check the button itself. Wires still attached, which is a good start. I short across the wires just in case the switch itself has thrown in the towel. Sparks and starter motor noises. You beauty. Oh well, that'll need replaced. Touching wires will do for now. Back to the engine.
Ok, new approach. What do we know?
Ok, from my basic understanding of carbs, the choke flap closes off the air and enriches the mixture to compensate for cold temperatures causing fuel to condense on walls of inlet manifold, etc. So as soon as we lose this extra enrichment the engine won't run. So, I try to adjust the mixture to get some more fuel in there. Give it half a turn each time then see if it will start. I get all the way to the end of the adjustment with no luck. I set the screw roughly back where is was.
New piece of theory. As we know the carb was in poor nick but still in service, it's possible that the mixture leaned off towards the end of the the previous engine's life, so the previous owner may have periodically wound the mixture more and more rich, to maintain the engine performance as the carb became more choked and was less able to deliver fuel normally. Worth a bash. Same approach as before. Half a turn at a time between starts.
I get bored of this quickly and give it 2 or 3 turns at a time. Eventually, I start to get a few splutters. These become burbles the further I go into lean territory. Eventually, I get to a point where it starts easily and idles pretty nicely at 900rpm. Yes, at this point I danced a jaunty little Scottish jig around the workshop. No denying that.
I do want to set the mixture properly with a CO probe, but I don't have one. Will have to ask around and see who has one and buy them some beer. For now, it'll do.
So, other than final setting of the carb mixture, the to-do list for next weekend's autotest looks like this.
|Set up carb mixture||high||1|
|Sort / replace rad cooling fan||low||1|
|Refit front clamshell||low||1|
|Select / inflate wheels & tyres||medium||1|
|Replace starter button||low||1|
|Unstick / clean brakes||medium||2|
|Repair exhaust gas leak||medium||2|
|Set rough steering alignment||low||3|
|Secure / route all cables, wires and hoses||low||3|
|Tighten / refit exhaust manifold heatshield||low||3|
|Flush water and add proper coolant||low||3|
|Spanner / fluids check||medium||3|
|Secure Ignition switch and check pin positions||low||3|
|General wash / clean / tidy||low||3|
Fingers crossed I can get through them in time!
Add a Comment