Would I be ok starting the engine and setting the gaps by sucking on the vac pipe? I could set them by RPM then, as it still doesn't seem to have the 1st stage right yet...
Anything's OK to try Sam! One thing that could be worth checking is that the vac nipple on the carb which goes to the lower pulldown connection isn't partially, or fully blocked. If I remember correctly there is a restriction, either inside the nipple on the carb, or maybe even in that end of the vac hose, down to quite a small diameter. It could be that it needs clearing with a thin bit of wire or similar. Yeah, just looked on the 'shed 2e3' and it's a really small hole, deep inside that vac nipple, looks like less than 0.5mm. May be difficult to poke something in there with the carb in-situ without risk of it snapping off or getting stuck in the hole. How about detaching the pulldown end of that vac hose, squirting in a touch of carb cleaner, then blowing it through? Check whether you you can blow/suck through the hose (attached to the nipple) as a first step though, there may be no blockage at all.
Started it earlier on, seemed like there was no choke at all, went to normal idle speed. Went out this evening to have a look, pulled the airbox off and decided to briefly start it. Went straight to fast idle, then dropped down to stage 2 with a small rev Only thing is, it doesn't seem to do this when the airbox is on. I'm thinking it could be the orange temperature regulator in the airbox? Just checking as i'd rather have a 2nd opinion before I spend 30 on one
The only way that the airbox thermostat could have an influence on start-up behaviour is if the vac pipe that goes from it to the base of the carb (or the other one, I guess) has a crack in it somewhere, and is causing there to be a below-throttle vacuum leak. This can/does happen because of the strain on the hose if the airbox is lifted without due care. I know because my old Polo with this airbox/carb had carb-icing problems for aaaaages before I discovered this reason. I can't really remember what it did with respect to fast idle to say whether this may have been affected by the cracked hose or not. Quite possibly may have an effect, easily checked by testing with that vac port on the carb open vs. blocked. If the airbox thermostat isn't getting its vacuum, or the other hose from thermostat to flap mechanism is leaking, it would stop the blender flap from working correctly, and likely cause carb icing, but that doesn't happen immediately after a cold-start, it takes a few minutes for enough ice to build up to affect things. There's also not much that can go wrong with these thermostats, other than getting clogged up with oil mist from the breather, and that can easily be addressed with carb cleaner squirted into all of its orifices. So, don't buy a new thermostat, do check the two vac hoses on it carefully.
Ah, think i've kind of eliminated it now too. Seems really strange, but car is too hot for me to do anything with now. Started it, got proper choke. I screwed the airbox down and started it, no choke (not decent anyway..), took off the nuts, started better.. Don't know if it is coincidence or not, but i'll have to investigate further tomorrow!
Changed the rubber mounting today, the old one wasn't in a very good state. Haven't got it started with choke coming on yet (Seems worse actually ), going to check that all of the hoses are still on/haven't worked loose when the carb was off.
I just went out and took the airbox off and got someone else to start the car while I watched the carb. She wouldn't start at first, then I pushed the adjusting screw on the front of the carb (Allen head one for PDU) in, and she started. Kept going when I took pressure off the screw. Then we tried starting it again, started fine. One thing I noticed was the adjuster screw was hitting the stop, but the carb was revving to 2200-ish. I suspect that if I hadn't of pushed the adjuster screw in to get her to start, it would've needed started with foot down on the accellerator (or it wouldn't start) (This happened last night, and after it started there was no choke). I've checked that all of the vaccum pipes are on, and they seem fine. Not really sure what to do now :/
Where are you Sam? If you aren't too far away I could come and have a look, but somehow I just know you're going to say Manchester or something... It sounds like the pulldown isn't getting a good vacuum, or maybe the TTV isn't working. I think yours will have a TTV, which will be at the end of the vac hose coming off the top pipe stub of the pulldown. Little round black thing with a 2-pin electrical connector on the opposite side to the vac hoses? Check for 12V at this wiring connector when ignition is on.
Bit far from you, NI Thanks for the offer though I have checked the TTV now, getting a solid 12v. I just went and started it again, took a bit of time on the starter to get it started. When it started it went straight to around 2300rpm. Sounds fine, but the PDU was at the 2nd position. Gave a short blip of the throttle and revs dropped to 1100-ish rpm (Still hitting stop at 2nd position). I think it *should* be something simple, but its figuring out what...
Do you mean that the allen-head screw tip is stopping the choke flap from opening any further? If so, that sounds right, that's what it is there for. Once the TTV closes off the top vac hose for you, the pulldown should open to the second stage (whatever dimension that's meant to be ). That screw is what adjusts the second stage max. opening, when the tip of the screw hits the stop that's all the pulldown can do, done. All further opening is done by the bimetallic coil spring. Have a play around with the adjustments, what dimensions are you at just now for first-stage and second stage gaps?
Yeah, but I haven't actually seen it at the 1st stage. Bit strange that it was at 2300rpm, and I gave it a sharp rev and it dropped to 1200rpm, without changing the position of that screw. Adjustments are roughly what you posted before.
Giving it a sharp rev will force the choke flap open, due to the so-called 'wide open kick' mechanism. Once you let your foot off the pedal again it should drop back to where it was, but... if the stepped cam mechanism is sticking (the bit behind the autochoke housing) it may be that this 'kick' is needed to get everything to find its correct orientation. Remember, it's the stepped cam that causes the revs to be higher at first, not the choke flap, that just gives a richer mixture. The choke flap can only make the revs lower than they should be if it's at an inappropriate angle for the temperature of the engine.
Turned the idle up a bit, and combined with the new rubber mounting, everything seems fine. Is there any way to change the duration of the choke? I think it may be coming off the choke a bit too soon.
If you rotate the outer cover of the autochoke (having loosened off the 3 clamping screws) you can adjust the duration of the choke action: I think clockwise should give you more duration, but I haven't fully woken up yet today. Try maybe 10-15 clockwise and see if that makes it better.
Nearly sorted! Do you know where the idle and CO/mixture screws are? Haynes isn't really that clear (And unless i'm looking at it wrong, the gunson book looks like it says the opposite!). I turned *a* screw to get the idle up (It did need about 3 turns after I changed the rubber mount..), but I've just realized this may be the cause of my horrible MPG (Sub 20 if my calculations are correct). Cheers
I think the idle speed screw is at the carb-end of that long plastic tube at the bottom of the above pic. Twisting the plastic tube may or may not actually move the screw, you may need to pull it off if it's slipping round without adjusting anything. Clockwise for faster, anti-clockwise for slower, I think. The mixture screw is lower down on the same side/area of the carb, right near the base, clockwise for leaner, anticlockwise for richer, I think.
