Hi there Couple of pics of my carb attached. Can anybody confirm that the port with what looks like a bolt shoved in around the remnants of some braided hose (to the right of the idle adjuster?) on pic one, and the longer braided hose running diagonally upwards from the back of the carb toward the air filter, are vacuum hoses for a vac advance dizzy? The rear facing one doesn’t plug into anything, just hangs there. These are historic works and I’ve been loathe to meddle as everything runs ok. Is there a more effective method blanking these ports? Assuming that’s the right thing to do? I have an 009 dizzy. Would having this arrangement cause any issues or damage anywhere?
The last guy left this port open, same carb and an 009 dizzy. I replaced the 009 with an 034 (svda) and connected them with a length of vacuum pipe. It made a world of difference in the bottom end and got rid of the low end stumble.
The hose for the vacuum operated hot air flap in the air intake spout on the air cleaner should come from near the bottom of the carburettor. This is meant to have manifold vacuum on it at idle to pull the flap open so hot air feeds the carburettor at idle and low RPM. The other connection goes to the vacuum advance mechanism on the distributor. This one is set up so that at idle with the throttle plate shut, there is no vacuum signal on it, but as soon as you put your foot down the vacuum appears and the timing advances. Changing to an SVDA will make the bus more responsive and slightly more economical at lower speed.
Thanks for this. I do recognise bogging low down the revs. Is dizzy swap fraught with danger of screwing thanks. I do recognise the low rev bogging so I might swap it out. Is the swap straight-forward or fraught with opportunities to create catastrophic failure? Any recommendations for places to, and not to, buy a dizzy from. Presumably best going for new?
I know there are some real expensive dizzies available (like the ones Ignition123 sell), but I didn't want to stretch to that - I bought a Powerspark 034 with their electronic ignition already fitted. It was only about 70 quid for the whole thing. Obviously cannot be Bosch quality for that price but I'm happy with it. Dizzies are quite easy to replace, but one thing to know changing to electronic ignition is that the #1 plug wire will move one position anti-clockwise on the dizzy. If you have a timing light you'll be golden, but you'll need one anyway to set your timing whatever you get (and its worth checking your timing from time to time anyway).
