daverclasper Posted November 26, 2018 Report Share Posted November 26, 2018 Hi. Wondering if these could do with replacing (Lucas 22D6). The cam doesn't quite return when it's moved by hand (maybe by about 1.5mm at tip of rotor arm), also any issues I have with pinking, are at higher revs, when accelerating, rather than low revs under load. Wondering if weak springs are causing it to advance too quickly/too much?. Any help great, thanks. Dave Link to comment Share on other sites More sharing options...
Clive Posted November 26, 2018 Report Share Posted November 26, 2018 Have you tried "mapping" the mechanical advance? diconnect vacuum advance, the take advance readings at 1000, 1500, 2000, 3000rpm. Check against factory spec. Only way to tell. But not returning could be springs, could be wear. Worth having a look at the weights, see if they are still "tight" ie not slopping about. (my Toledo was dreadful, I got max 17 degrees of advance over an initial 10 degrees, well out of spec but now corrected by spending (semi-serious) cash.... Link to comment Share on other sites More sharing options...
dave.vitesse Posted November 26, 2018 Report Share Posted November 26, 2018 Weak springs can cause pinking at mid to higher revs. Pinking at half throttle is normally caused by too much advance from the vacuum unit. Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 26, 2018 Report Share Posted November 26, 2018 Its fairly normal they dont return when turning the rotor as your making workmback to front , worn springs will give too much advance to early as its lucas its easy ....... if its delco ....not easy The vac unit can offer too much advance , with modern fuels the numbers on the canister are the vac it starts , the vac max, and the max degrees it advances Eg 5-11-7 so playing with units of varying specs can improve some throttle related pinking Link to comment Share on other sites More sharing options...
daverclasper Posted November 27, 2018 Author Report Share Posted November 27, 2018 thanks everyone. Pete. Not sure "what's easy" on Lucas. "not easy" on Delco. Cheers, Dave Link to comment Share on other sites More sharing options...
Pete Lewis Posted November 27, 2018 Report Share Posted November 27, 2018 the lucas springs are simple to pop off with the base plate removed, you may like to undo the centre screw and just lift the cam spindle and weights onto the lounge table . on a delco they are encased in a pressed housing . you cant do much other than wreck it as youre on lucas ...think yourself lucky Pete Link to comment Share on other sites More sharing options...
daverclasper Posted December 20, 2018 Author Report Share Posted December 20, 2018 Hi. Thought I would give the mapping a go as suggested and bought a second hand (though unused) Gunsons Neontune strobe. The FWM gives figures at 500, 600, 1500, 2300, 4600, 6400 RPM. What's safe to go up to please?, bearing in mind my engine is well used. Thanks, Dave Link to comment Share on other sites More sharing options...
Clive Posted December 20, 2018 Report Share Posted December 20, 2018 5000 should be a doddle even on a well used engine (if it isn't OK, the engine must be knackered) Plot a graph of the book figures, and add you actual figures. Surprised it goes to 6400rpm, usually max advance is around 3000ish. Don't forget to disconnect vacuum advance when you do the checks. Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 20, 2018 Report Share Posted December 20, 2018 just to add read the manuals specs well, my days of testing and some manuals give degrees advance..... decelerating and dont forget the dizzy figures are half the engine figures Pete Link to comment Share on other sites More sharing options...
Clive Posted December 20, 2018 Report Share Posted December 20, 2018 I hope the 6400rpm is engine speed! (not dizzy) The mapping using a timing light is really a bit crude, but is enough to decide if a distributor is OK or beyond help... Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 20, 2018 Report Share Posted December 20, 2018 Clive i hope so too !! back f the triumph manuals is a load of test data which needs reading backward twice before starting off, but youre right any results will give up some clues happy whatever pete Link to comment Share on other sites More sharing options...
Nick Jones Posted December 20, 2018 Report Share Posted December 20, 2018 Maximum advance is usually all in by 4000 rpm (engine rpm). Link to comment Share on other sites More sharing options...
JohnD Posted December 20, 2018 Report Share Posted December 20, 2018 Picture worth a thousand words , Little Grasshopper. (From GT's book, but I hope he can't claim it as his!) Link to comment Share on other sites More sharing options...
daverclasper Posted December 20, 2018 Author Report Share Posted December 20, 2018 Thanks for the response folks. I think I read the figures correctly for Mk1 2 Litre in FWM at deceleration, at the crank 4,600 RPM = Min 15/Max 19 advance 6,400 RPM = Min 16/Max 20 advance So around 19.5 max advance at 6000 RPM possibly give or take. This appears way different from above graph which I'm reading as about 32 advance at 6000 RPM?. Yours, confused Link to comment Share on other sites More sharing options...
Pete Lewis Posted December 20, 2018 Report Share Posted December 20, 2018 Dave you need to add the static to your figures then its about the so add +10 ??? Not many have more than 32 at 3000 29 to 32 at 3k s a good all rounder Link to comment Share on other sites More sharing options...
Clive Posted December 21, 2018 Report Share Posted December 21, 2018 Yes, a simple measurement at idle and 4000rpm should be enough as a basic guide. In fact one method of setting timing is to use 30degrees at 4000rpm, then see what you get at idle (10 degrees? depends on the car a bit... My Toledo was set up to give(just ) no pinking. But it was about 18 degrees at idle and rising to a mere 24 degrees, all down to very work advance weight pivots as well as slack springs. I got some springs (much easier on a lucas as the distributor doctor keeps them) but the delco one the suppliers keep were all too long, but I anaged to find some shorter springs and also a new dizzy from another car (had to alter the max advance on the baseplate buy building it up with weld) This gave me new pivots taking up all the slack there (about 8-10 degrees!) Can now pulls better through the low/mid range, and I get an extra 1-2mpg on the RBRR. I am tempted to try giving it a couple more degrees of max advance, see how that works. But it is a faff. Link to comment Share on other sites More sharing options...
daverclasper Posted December 21, 2018 Author Report Share Posted December 21, 2018 Thanks Guys. Will give it a test when I have some free time Dave Link to comment Share on other sites More sharing options...
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