glang Posted August 4, 2016 Share Posted August 4, 2016 Dave what does yours do when you press the carb piston plungers or if you wind the mix adjusters up a half turn? Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 4, 2016 Author Share Posted August 4, 2016 thanks i think im slightly rich to be honest based on my colourtune and what you say if its woth messing with blindly as i am is another thing could just be worth leaving it 2/3 MPG doesnt really matter i guess Quote Link to comment Share on other sites More sharing options...
glang Posted August 4, 2016 Share Posted August 4, 2016 I understand your reluctance to fiddle but if you're careful you can always return to the original setting. Youll know when its too weak as the engine loses power quite drastically and tends to run on after you turn off the ignition however the advantage of correct mixture isnt just fuel encomomy and cleaner plugs but also less carbon build up on the valves and combustion chambers..... Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 4, 2016 Author Share Posted August 4, 2016 yes your right half a turn back then i guess and i will see i have gone weaker before and your right you really notice the lack of power . there is nobody old school mechanic now in cheshire with experience setting up these engines now. there used to be a person called max who was great but he has retired now. that said he always said set them rich Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 4, 2016 Author Share Posted August 4, 2016 just tried the piston spring again to see how mine is. if you just press very quickly and let go like a stab the revs do not change they only rise if you keep your finger pushed up on the piston spring then they fall as soon as you let go is that correct? Quote Link to comment Share on other sites More sharing options...
glang Posted August 4, 2016 Share Posted August 4, 2016 Thats it - not a very precise method but the best Ive found as even with a Colourtune the results are pretty variable. Now give it a few good runs and you should see the tail pipe go a slightly greyish colour rather than sooty black.One other thing: I take it the airfilters are good? Heavily restricted filters would give richer running..... Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted August 4, 2016 Share Posted August 4, 2016 The piston lifter needs a very light touch , lift till you just feel contact with the piston and then raise about 2 mm note what happens, do not just yank the thing up, its all light touchy feely any accelation will richen the mixture as that the dash pot doing its job, it acts as the accelerater pump to loose flat spots if its toppednup with engine oil, not cats pee.it takes agoodnfew miles to burn off town and choked start drivingor just turn the mixture leaner till the revs start to drop then back off 1/4turn to return to its best running positionany idea they need to be set rich is wildly misguidedIf you have piston springs fitted to a 1600 carb it will always be too rich when runningWith std needles, needs the heavy damper weight what needles are fitted ????pete Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 4, 2016 Author Share Posted August 4, 2016 hi Pete the needles are new and the correct standard ones from charles paddock for the 1600 engine. as the replacement refurbished carbs were taken from a mk1 2 litre i was advised they would have the wrong size needles in them so i changed them.air filters are good very new although if they have been ruined by the carb flooding ? Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 4, 2016 Author Share Posted August 4, 2016 excuse my ignorance here im certainly no expert just learning as i go along. So when you say piston springs do you mean the big dash pot spring thats there when you take the top of the carb?if so they are fitted on both carbs and they were fitted on the original ones i replaced i assume had been on since new . should i take these springs of then and the result will be a leaner mixture. the Oil in the damper is standard 20w/50 engine oil not 3 in 1 ect ? Quote Link to comment Share on other sites More sharing options...
glang Posted August 4, 2016 Share Posted August 4, 2016 Yes the piston spring is the big one that must be used to make sure the piston returns positively to its fully down position. It sounds like you have everything correct with the change of needles and I dont think either the flooded filters or engine oil will make much difference (the latter should be SAE 20 so a bit thinner but the damping effect is only during acceleration and not constant running). Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 So should the piston springs be in or out on these carbs on the 1600 engine ? Quote Link to comment Share on other sites More sharing options...
mazfg Posted August 5, 2016 Share Posted August 5, 2016 Quoted from zhcj So should the piston springs be in or out on these carbs on the 1600 engine ? I have CD150's on my Vitesse 6 and never had springs on the dampers. As Pete said, the weight of them is enough. Later cars with CD's did have them fitted. I have a document called Tuning Stromberg CD carbs.See picture for an excerpt showing when springs should be fitted and what needles. Quote Link to comment Share on other sites More sharing options...
thescrapman Posted August 5, 2016 Share Posted August 5, 2016 What is an Ajax 1500?? Quote Link to comment Share on other sites More sharing options...
glang Posted August 5, 2016 Share Posted August 5, 2016 Quoted from zhcj So should the piston springs be in or out on these carbs on the 1600 engine ? I would have thought that running without em would tend to make the mixture richer but give it a try and see what its like - cant do any harm Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 now i am confused i thought according to the other thread from Pete it would run richer with the springs ? Quote Link to comment Share on other sites More sharing options...
glang Posted August 5, 2016 Share Posted August 5, 2016 Come to think of it I dont think there'll be any difference because at any particular throttle opening the low pressure applied to the carb before the piston is what acts on the diaphragm to lift the piston. If the piston is held more closed because of the spring said pressure will be lower so giving more force to the diaphragm to lift the piston until an equilibrium is reached - easy! Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 ive taken the springs out interestingly the back on was an inch shorter than the front one ill see how it runs Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 Quick spin and I could not tell much if any difference with the springs out crept the tick over engine speed was faster by approx 200 rpm that was not responsive to slow down with the throttle screws turned back so I'm guessing taking the spring out made it richer ? Putting the springs back in lowered the tick over speed back down Quote Link to comment Share on other sites More sharing options...
glang Posted August 5, 2016 Share Posted August 5, 2016 I think its more likely the springs make sure that the pistons return to fully down - without them it would only need a little friction to keep one open slightly so changing the tick over. However I do think they should be the same length Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 yes i thought about that if one of the pistons was not fully clunking down it could have been that id have to try it again the tick over was around 900/1000 RPM with the throttle adjustment screws not really touching so i assume removing the spring did as you said and made the mixture richer so raising the revs, so in such case i would have to turn the mixture screw in to drop the revs to weaken the mixture?or is that not correct at all !! Quote Link to comment Share on other sites More sharing options...
glang Posted August 5, 2016 Share Posted August 5, 2016 I think if you cant find any improvement without the springs you're better off running with them as this should ensure ensure that the pistons are fully down and the tickover correct.As we've been discussing this Ive learnt some stuff as well such as the possibility of centering the jet so that the needle and piston return smoothly and positively to the closed position. Have a look at this site:http://www.howacarworks.com/fuel-systems/adjusting-a-stromberg-carburettor Quote Link to comment Share on other sites More sharing options...
zhcj Posted August 5, 2016 Author Share Posted August 5, 2016 thanks for the link ill have a look i think as you say ill leave the springs on for now anyway Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted August 5, 2016 Share Posted August 5, 2016 Quoted from thescrapman What is an Ajax 1500?? Triumph 1500 FWD at a guess, since 1300 FWD was code named Ajax......Mark Quote Link to comment Share on other sites More sharing options...
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