Another thing I find weird is that the top step of the choke cam seems to not be on the fast idle screw. So I slacken the choke unit and rotate it slightly so that the choke spring is providing a bit more tension and the cam is where it should be. Then the next day I go out to the van the choke cam is too far tensioned so the hot idle is sitting on the very top part of the cam (which it shouldn’t be?). So then I put it back again and round in circles I go.
Using a mirror I would loosen the choke housing and rotate it a little, the flap inside the carb will open and close. It should only be a tiny fraction open when the engine is cold. (That's my understanding anyway) Or possibly the element has become distorted?
How many steps you use depends where you live. As we are not in the arctic circle you really don't need the choke on the top step. Often in the uK a couple of steps is enough. More important is that once warmed up it sits on the bottom step.
When you set the choke position, it was probably with a hot heater in the choke capsule, so the choke mechanism is rotated because of the hot bimetallic strip. If you change the setting then, you are over-closing the choke when it gets cold next morning. It takes a while for it all to cool down again, so fiddling with the setting above a warm engine is not going to be right. As soon as you turn on the ignition, the choke heater starts working, even if the engine isnt running. Then once the engine has been running, the carburettor stays warmed by the heat coming off the engine. As @Zed says, the main thing is that after a few miles of driving, the heater warms up, the choke flap opens and the stepped cam can drop so the screw is on the bottom step.
I didn’t realise the choke would heat up with the ignition on, I thought only with the engine running would the power be supplied. I was only adjusting it with a cold engine. I thought the outside temp might even be effecting it but that seems a little too extreme. I have now done compression tests on all cylinders. With a cold engine and removing only one plug at a time and the others left in. Then another test for each with a little bit of oil down the cylinder. First Time No 1 - 95 psi No 2 - 85 psi No 3 - 110 psi No 4 - 82 psi With Oil in Cylinder No 1 - 102 psi No2 - 90 psi No 3 - 115 psi No 4 - 87 psi Thoughts?
How to compression test. Take ALL the plugs out. Remove the 12v supply to the coil and be sure it won't short to earth (earth is anything metal) Keep your foot on the throttle to let the air in to be compressed. If you can, it's good to rig a wire to the starter spade than you can dab onto the battery + If you do that you can leave the ignition off and you don't need to disconnect the coil supply. Also you can watch the test meter to see when it stops increasing. You can hand operate the throttle. My guess is you need to do it again. I've never done it on anything but a cold engine. I would do the test again with all the plugs out, full throttle, watching the meter, I'm guessing you may not have done the test correctly.
So I did the compression test again with all plugs out and throttle wide open and choke open. No 1 - 110 psi No 2 - 97 psi No 3 - 120 psi No 4 - 95 psi
Well they're higher. Bit of a spread between lowest and highest but hey, it was a cheap (?) temp engine out of some guy's shed. Nothing there that would cause you to abandon. One day you might replace the rings and grind the valves and find them all up around 120psi.
So I am now trying to set the timing with my new timing light. I have read a thread a couple of variations one says to set the timing at 28-32 degrees, trying 32 first at 3,000+ rpm. Another says 30 degrees at 3500 rpm. This is my first time trying to time the engine so just wondering what I should be aiming to set it at?
Set it at 7.5 idle then add revs until the timing stops advancing - that's max advance. You might get there at 3,000 rpm or it might be higher - the revs are not the important thing, the max advance is. if it's 30 or 32 that's ok for a type-1 engine. Any more is too much. Less is unlikely. Then report back.
So I have had another go at timing. It seems that 7.5BTC produces something way over 30 degrees so I had to adjust the distributor. I am now at 32 degrees at over 3000 rpm when it stops advancing. On idle with the engine running at about 850 rpm it is at only 1 or maybe 2 degrees. What does pinging actually sound like and how would I know?
Like a ticking, will happen at low revs up a hill with your foot down i.e. when engine is under a lot of load. Your distributor is rubbish btw, it has way to much advance. You might improve it a bit by bending in the stops the weights hit at full advance. A problem with 1 or 2 degrees at idle, as I'm sure you've found, is it slows right down which will cause you to make bad adjustments to the carb speed it up. On the other hand you probably had 38+ full advance when you were saying it bogs down at 3,000rpm which would explain that. Do you have another distributor that might be better?
No I don’t, is it worth buying another one or run this and see how it is? Are the brand new SVDA ones from Heritage and JK rubbish or good? The missing spring under the distributor I think really helped the bogging issues which was at 1-2k. It didn’t run too badly with the static at 7.5BTC so as you say probably 38 degrees advanced, I did feel a bit underpowered but that might be the compression etc.
If it fires too early, the main burn happens before the piston reaches the top, pushing it back the way it came = gutless. IDK about new distributors, maybe someone else will chime in. meanwhile you can improve yours by bending those stops in. Looking back at your crappy one spring distributor pic I see the weight in the photo doesn't move far, it's not going to be the one proving full advance, I'd ignore that and bend the other one. Maybe even take the spring back off the one that doesn't move far. Have to admit a one spring non vac distributor is not something I'm familiar with as normally I'd throw such a thing straight over @snotty 's fence and get an SVDA rather than trying to get it to work.
Having put a new svda on mine I can tell you: the rotor arm was diagnosed as being too loose and the vac can failed within its few hundred miles of operation. Having replaced both, it's not made an appreciable difference to performance but then, I'm broadly clueless as to setting it all up. Like most things, it probably won't just work after putting it on but you seem to be a competent tinkerer.
GSF will sell you an SVDA distributor for £28 free post, I'd be inclined to do one of 2 things - either buy a really cheap one based solely on price because they are all going to be a bit rubbish, or seek out an original refurbished one at great expense.
Ive just fitted one of these while the 123 is at vwJim for assessment... works fine on the type4 for me so far, i just set to max at 30deg and ignored idle as long as it does idle which is about 900ish Sent from my SM-T580 using Tapatalk
Is there a top of the line one that I could buy and could transfer over to a bigger better engine that I will hopefully build/fit in the future, like a 1776 with twin carbs? If I am going to spend quite a bit I would just like it to be good and useful on a better performance engine. All these numbers 1234, 034 etc don’t really mean anything to me. For instance is this the best distributor you can buy for a type 1 motor? https://www.heritagepartscentre.com/uk/ac905d186-pertronix-ignitor-1-billet-distributor.html
