Triumph 2L Vitesse vacuum readings with Mikuni HSR carbs. 

So I fitted Mikuni HSR carbs to my Vitesse, these carbs use Manifold vacuum rather the the standard Ported vacuum for the Vacuum Advance take off pipe. I dialled the mixture in with an air/fuel meter so it was perfect except the initial throttle opening which is controlled by the slide, trouble is, Mikuni do not sell alternative slides and I didnt want it to rich all the way up the needle jet range just to sort out the pull away leanness. So I disconnected the engine breather which plumbs into the inlet manifold and therefore lowers manifold vacuum. This completely cured my initial leanness, but them gave me the problem of pinking on acceleration. Disconnecting the Vacuum Advance cured this, but I still want to retain the advantages of VA, and so have bought a TR3 VA which can be adjusted by fitting different springs. The standard VA starts to open at a vacuum of 6, I determined that on my car now, gentle acceleration takes my vacuum down to 12 and I don't want any additional Vacuum Advance with any harder acceleration that lowers the vacuum past 12. So I will try a stiffer spring and measure with a brake bleed gauge to ensure it doesn't start to advance earlier than 12. This film therefore, with no VA but a gauge connected to the manifold take off point, is for me to determine when I wish my vacuum advance to start. These carbs by the way are not CV carbs. In retrospect, I should have connected this gauge to the spare port and left the VA attached and in operation, that way I could have seen exactly at what vacuum reading pinking started to occur, this video would also have been more relevant if I concentrated on less spirited driving as a wide open throttle drops vacuum past the point of the standard VA opening point anyway. I am confident however, that the gentle level of acceleration that reads higher vacuum than 12, will be OK, but anything with a higher load that would drop the reading below 12, is best I avoid any additional advance. Apologies that the film is upside down and that you may have to turn your sound up to hear my comments and what the car exhaust is revealing.