DFD702K. Feb 24, 2019 19:34:41 GMT via mobile
Post by rosieuk on Feb 24, 2019 19:34:41 GMT
When did the car last have a full service?
The issues could be ignition braking down through age. If new plugs improved things I would consider changing the whole ignition side (points, distributor cap, rotor arm condenser and plug leads). All are fairly cheap and readily available parts and at least you will know it’s not an ignition issue.
If it’s not had a lot of maintenance I would also give the carb internals a clean and a new air filter.
It was supposed to have had a full service when I took it to the garage for one. I suspect it didn't - certainly whatever spark plugs were there were bunged in whether they were right or not. Plugs have all *9s and it's now much smoother, will change cap & leads but the other bits are going to be replaced with electronic, more to the point I physically can't stay in that position long enough to get the bits out let alone get them back in with any chance of them working properly.
It's had an air filter and wasn't that a bloody palaver - but I'm going to fab up a long heimholtz type plastic intake with a k&n type filter at the grill end. The intake can won't seal properly but that's going to get some judiciously applied duct tape for the moment.
Crud in the jets and at the bottom of the float chamber could be causing fuel flow issues that would confuse things as would bad air flow
Once those are done then I would look at timing from a starting point of fuel and spark being correct.
It's had a fuel filter on it since I got a new fuel line on it and it's now running clean. I don't have the tools or health to start pulling that sort of stuff off the motor.
I have a suspicion the engine is overcooling. Because I now have a cold air intake pipe from grille to trumpet into carb, not with the trumpet sucking past the exhaust it doesn't get hot intake air and after a longer run than usual the odd misfire almost disappeared - it might even be pushing in the choke too early. I think the trumpet pointing down might be a BL bodge - that very tight cowl pulls a lot of air through - I wonder if it pulled too much and a quick bodge "fix" was having a permanently hot intake charge (horrible for power, but helps slightly with pumping losses). If I could pull the octopus plate between the block and radiator - remove the upper cowl - replace the plate & test - I suspect it'd be sitting right in the middle of the N zone on the gauge.