I would go back and look at the fuelling. Your issues are a common reported problem on here, a forum search may help. I doubt its electrics.
Just read through the post again. If its hesitating just off idle & cutting out at idle it will most likely be a fueling issue. Ignition issues normally give either a miss fire or a cutting out when driving or non start. I removed the original solex carbs some years ago & fitted Weber ICT’s. I had also had overhauled the carbs even replaced the worn butterfly spindles. But still had issues, the mixture screws would wind themselves out due to vibration from the engine causing poor running. Have you checked the mixture screws? Can’t remember the baseline setting but it’s normally 2 1/2 turns out from the stop. Failing that it could be dirt somewhere in the carbs. Does it have a fuel filter fitted?
Ive just had similar. I replaced the points and condenser. Now all good. Remember to look after the timing when removing the distributor.
What type and grade of spark plugs do you use and when was the last time the valves were adjusted, timing checked and fuel filter changed? You won’t have a condenser with electronic ignition but the Pertronix module and or coil could be failing.
Plugs looked ok, but I changed them anyway. Got the oem oil bath filter, took that off and checked everything, now put it back on. Checked the timing..if I hold the revs to about 900, it's about 8 Dec btdc. Revs to about 30 degrees. If you let the tickover drop to when it nearly dies, probably about 300-400 timing goes down to about 4 degrees. Felt dizzy..it's nice and tight. Fuel filter looks clean, its less than 2 years old, but plan to change it anyway. Run some redex straight through the carb to try and clean out any crap. Must admit I'm out of my comfort zone taking the carbs apart. Did change to exhaust a few months ago for a good used one..oem.
Might be worth checking exhaust gaskets not leaking. Lost all power when bits fell of my old stock one. Stainless is great.
Ok that makes sense. The timing should not drop below 7.5 BTDC at idle. It is a hard endstop!! Either you have the wrong vacuum hose connected, the one you want should not suck at idle, or the throttle plate is uncovering the first hole in the carb at idle... This causes advance that goes away if you pull the hose off the distributor (and block it off to the carburettor as if it sucks air thats a vacuum leak) . The other mistake is to set idle RPM over 1000, amd try to set timing, when the centrifugal advance cuts in and provides a few degrees of advance which drops if RPM ever drops... Basically you have timed it to 4 degrees BTDC and an idle speed of 400 rpm . Static time it to 7.5 BTDC if you cant estimate 750-850 rpm idle speed and try again. Been there , done both these myself.
I have timed to 7.5 dbtdc at 800rpm, that hasn't changed, but the engine revs now drop below 800, which drops the timing below 7.5 degrees. I haven't changed any hoses from the dizzy..is there a check I can do to check the dizzy is working properly and find out why the timing drops below 7.5 degrees when the revs drop below 800. I haven't changed anything, so something appears to have broken or changed. When I changed the exhaust a month or so ago, I noticed there seemed to be a lot of pressure coming from the tailpipe..not sure if that could be a clue? I will remove the exhaust and check the gaskets but can't feel any blow. This is really starting to do my head in now.
The correct advance hose is the one that doesnt suck at idle. Just because you didnt change it doesnt mean it was right before. I had to fix a lot on an engine apparrently fitted by T2D a few Techenders back.. Timing is done with hoses off the distributor so it doesnt advance with vacuum leaking at idle. Amd below 850 rpm so the advance has stopped centrifugally advancing.. If it DROPS below 7.5 unless its a dual vacuum distributor, the value it DROPS to is the ACTUAL idle/static advance. And you might need to lubricate the advance mechanism .. it could be sticking.. take off rotor arm and put a few drops of 3 in 1 or engine oil on the felt pad in the top of the shaft. Set the 4 degrees to 7.5, hoses off. If it wont run for long enough, rig a remote starter wire to the tag on the starter motor that you touch in the battery to operate the starter. If it now revs high, now adjust the idle. Or set static timing to 7.5 degrees, and then check what the timing light gives you. Then check its under 30 degrees at 3000 rpm.
Further to that.. I was driving country roads tonight and when I slowed down for the motorway .. Familiar... Slow idle, lean.. died at the other end of the motorway... restarted instantly.. So I took the carb off just now.. Blew out the 47 primary idle jet.. which looked maybe a bit blocked.. Normality returns, idle is a bit slow the engine has cooled a bit
Just as s note! I used to use the lamp method of timing mine! I.e. timed without the engine running and was always fine when strobed. I’m not sure how your timing could drop below that unless you have a retard facility on your dissy
Changed the exhaust..made no difference. Changed the whole oil bath filter assembly to some cone filters that came on the bus when I bought it...made no difference. So, had a look at the timing. Couldn't get it to idle no matter how I moved the dizzy. It has been dropping to below zero, but after I adjusted it a bit it is now 7.5 dbtdc at about 500 revs, and doesn't drop below 7.5, like it did before. The engine now ticks over and sometimes does stall as the revs get too low, but I cannot get it to run at more than 500 rpm no matter how I adjust the timing. So how the timing looks ok, how can I just adjust the idle speed without changing anything else, fuel mixture, etc.?? If it is just a screw, can someone post a picture of where the necessary screw is. Many thanks again.
If you dont have endstop screws on your carburettors, the throttle can close totally, that might not help .. you mention flaps and empty screw holes..can you take a picture ?
Does that increase the mixture or have any other effect other than increase the idle.. is that the big screw in the tube on top of the left hand carb? No leaks traced anywhere btw.
Yes it's the larger of the screws in a recess, and no it won't have any detrimental effect on the mixture.
