Ben Freer Posted August 11, 2016 Report Share Posted August 11, 2016 (edited) Well hopefully the title got your attention! Whilst staring in wonderment at the fuel lines installed by the PO (which I am planning to reroute to avoid vaporisation) I noticed this nipple on the rear carburettor. What should it be connected to? Should it even be there!? Might it account for the weaker mixture on 3&4? Edited August 11, 2016 by Ben Freer Quote Link to post Share on other sites
McMuttley Posted August 11, 2016 Report Share Posted August 11, 2016 (edited) I am no expert on carbs, as this forum proves, but when one appeared on my re-built carbs, i asked Andy Turner, who replied "vacuum advance" I wasn't sure what that meant, so sealed it with some heat shrink for now Edited August 11, 2016 by McMuttley Quote Link to post Share on other sites
Ben Freer Posted August 11, 2016 Author Report Share Posted August 11, 2016 Thanks Austin, that makes sense and is confirmed by a PM from Tom (Fireman049). They are HS6's I know that much! I have no vacuum advance tube fitted from the distributor - possibly because it is a 123 unit and doesn't need one? I'm sure some one on here will know! P.S. I'm surprised you could bring yourself to look at such grubby carbs compared to Ol' Smokey's blingy ones!! Quote Link to post Share on other sites
Ian Vincent Posted August 11, 2016 Report Share Posted August 11, 2016 (edited) There are 123 units without a vacuum advance module. I have one but to be honest it doesn't work as well as a regular properly set up dizzy for normal day to day driving. Incidentally, I have HS6 carbs and the vacuum take off is on the front carb. Rgds Ian I have edited this post to reflect what I meant to write and not what the autocorrect typed for me. My 123 doesn't have a vacuum module. Edited August 13, 2016 by Ian Vincent Quote Link to post Share on other sites
Ben Freer Posted August 11, 2016 Author Report Share Posted August 11, 2016 (edited) Thanks Ian Here is a pic of my 123 dizzy with the tube. I'm not sure whether to just blank off the nipple or install a tube Edited August 11, 2016 by Ben Freer Quote Link to post Share on other sites
BlueTR3A-5EKT Posted August 11, 2016 Report Share Posted August 11, 2016 My carbs are HS6 and the vacuum takeoff for the distributor A/R is on the rear carb. Peter W Quote Link to post Share on other sites
Lebro Posted August 11, 2016 Report Share Posted August 11, 2016 Mine happens to be on the rear carb, but it does not matter - either will work. If not using vacuum advance then it should be blanked off. Bob. Quote Link to post Share on other sites
peejay4A Posted August 12, 2016 Report Share Posted August 12, 2016 (edited) I would connect the 123 to the vacuum takeoff. It's there to allow more advance at cruise for improved fuel economy in theory. I've never seen an advance takeoff at the front. It needs to be near the throttle plate to work if all the bumf I've read is true. Edited August 12, 2016 by peejay4A Quote Link to post Share on other sites
Lebro Posted August 12, 2016 Report Share Posted August 12, 2016 I've never seen an advance takeoff at the front. It needs to be near the throttle plate to work if all the bumf I've read is true. Ben's photo shows the take off on the manifold side of the carb, which is correct. it does not matter which carb is used - front or rear. Bob. Quote Link to post Share on other sites
McMuttley Posted August 12, 2016 Report Share Posted August 12, 2016 are these vacuum thingamys a plug and play job, or do they involve lots of fettling of the dizzy and degrees of whatever ? I don't believe that I have a 1,2,3 Quote Link to post Share on other sites
Lebro Posted August 12, 2016 Report Share Posted August 12, 2016 With a standard distributer just connect it up. Bob. Quote Link to post Share on other sites
Ian Vincent Posted August 13, 2016 Report Share Posted August 13, 2016 Ben if you have a 123 with vacuum connection you should use it. It will improve the tractability of the the car no end. It's purpose is to retard the ignition when you open the throttle thus allowing it to accelerate smoothly from low revs. Rgds Ian Quote Link to post Share on other sites
Ben Freer Posted August 13, 2016 Author Report Share Posted August 13, 2016 Ian, thank you. I have ordered one from Moss. It will be interesting to see if it improves the car's behaviour. Quote Link to post Share on other sites
peejay4A Posted August 13, 2016 Report Share Posted August 13, 2016 Ben's photo shows the take off on the manifold side of the carb, which is correct. it does not matter which carb is used - front or rear. Bob. Yes I read that wrong. Front carb, not front of carb. Quote Link to post Share on other sites
Ian Vincent Posted August 13, 2016 Report Share Posted August 13, 2016 are these vacuum thingamys a plug and play job, or do they involve lots of fettling of the dizzy and degrees of whatever ? I don't believe that I have a 1,2,3 What sort of dizzy do you have Austin. If it is a normal DM2 or 25D it should have a vacuum advance unit and the car will run much better with it connected. Or at least mine does. Rgds Ian PS I had been using the 123 unit but it didn't offer much low revs tractability so I replaced it with the original DM2 that came with the car, which I had rebuilt and fitted with a new vacuum unit from Martin Jay. The difference was a revelation. Quote Link to post Share on other sites
Ben Freer Posted August 19, 2016 Author Report Share Posted August 19, 2016 (edited) I have installed the vacuum tube http://www.moss-europe.co.uk/vacuum-pipe-metal-12h733.html?assoc=115410 from Moss. I guessed how to mount it but it seems to work! It was "plug & play" Austin - although the tick over speed needs adjusting up a bit (this might be a coincidence!). I did have to trim a bit off the end to make it fit the bracket which I mounted on the carburettor to manifold stud. You will also need two rubber connectors. @ Ian. It has indeed improved the smoothness of the acceleration considerably. PS edited as I realised (thanks Tom!) that I had mounted the vapour trap upside down! Edited August 19, 2016 by Ben Freer Quote Link to post Share on other sites
peejay4A Posted August 19, 2016 Report Share Posted August 19, 2016 Ben if you have a 123 with vacuum connection you should use it. It will improve the tractability of the the car no end. It's purpose is to retard the ignition when you open the throttle thus allowing it to accelerate smoothly from low revs. Rgds Ian Vacuum advance for cruise economy surely? Quote Link to post Share on other sites
Lebro Posted August 19, 2016 Report Share Posted August 19, 2016 +1 Quote Link to post Share on other sites
Ben Freer Posted August 19, 2016 Author Report Share Posted August 19, 2016 I now look forward to getting the sort of mpg that you reported from your trip to Lincoln Bob! Quote Link to post Share on other sites
Ian Vincent Posted August 19, 2016 Report Share Posted August 19, 2016 Vacuum advance for cruise economy surely? The vacuum advance allows you to achieve the right amount of advance that you need for maximum economy when cruising. As soon as you open the throttle the loss of vacuum retards the ignition allowing the engine to pull smoothly. I know we are saying the same thing but it is much more logical to me to picture the purpose of the module being to allow the ignition to retard when the throttle is opened. Rgds Ian PS If you don't have it connected it is your low speed tractability that tends to suffer. Quote Link to post Share on other sites
peejay4A Posted August 19, 2016 Report Share Posted August 19, 2016 I don't want to labour it Ian but there's little or no vacuum advance at idle as the port is covered by the butterfly so you're at static advance only. As revs increase you get some centrifugal advance and some vacuum advance depending upon how you feather the throttle. No retard though. Quote Link to post Share on other sites
Lebro Posted August 19, 2016 Report Share Posted August 19, 2016 Now then chaps, put those flintlock's down ! We are all saying the same thing. "advancing" or "retarding" it's all relative. When you put your foot down at cruise the ignition retards back to where it was before the vacuum advance was in effect. Bob. Quote Link to post Share on other sites
peejay4A Posted August 19, 2016 Report Share Posted August 19, 2016 (edited) I guess I was saying that the capsule can only provide advance. More or less advance for sure and if you want to treat less advance as retarding that's fine. Edited August 19, 2016 by peejay4A Quote Link to post Share on other sites
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