So just got a strobe and trying to check timing, accept that this is a daft question, what marks am I firing the strobe at?
got it and white painted it, next question, what am I setting it to? currently it is..6 degrees BTDC...its a 2.0 liter CJ code engine , 1979, twin carbs...if I read Bentley its about right (7.5 BTDC).
Disconnect the vacuum advance, then with engine at high revs, set it to max advance of 28 degrees. At idle it should be roundabout 7.5 degrees but its the max advance that's important as you don't drive around at idle.
Same 28 degs required for the mech advance on SVDA distributor, which is why required to disconnect the vac pipe.
Take a look at http://wiki.club8090.co.uk/index.php/Petrol_engines_aircooled_Ignition_02 It's got various methods used for timing whether you've got 009 sva or one with a retard. But I do think my method above is sound.
I take it that's 28 degrees below TDC?? SO this means doing it dynamically ie with the engine running, is there any chance of serious screw ups if you spin the dizzy in the wrong direction??
Just turn the dizzy slowly, don't think you can do any damage if you turn it too far. But you won't, it's dead obvious once you start turning, especially if you can get a helper to hold the timing light. However you can do serious damage if the timing is set wrong and you go on a long journey. So maybe set it, then check it again in a days time to make sure you've done it right.
Not saying anyone is wrong at all but ive always set mine at fast idle to 7.5deg before top dead centre. Dissy maxes out around 30 btdc approximately. My issue with setting at "max". What do you call "high revs". on an unloaded free reving engine you can rev to distruction if you want but you will never experience such high revs on the road. Happy for someone to convince me but also it depends on what strobe you have. My cheapo gunson thang wouldnt necessarily be firing correctly at 5K plus rpm aso im setting at, what... 750? I used to static set to 7.5 btdc and now set timig at tickover to 7.5 btdc. havent blown one up yet but maybe im doing it wrong???
Interesting comment dicky. I am not sure i am happy setting the timing dynamically. I will check tomorrow at higher revs but am not going to adjust. Mine was reading 6 at Rickover today so will prob adjust a bit to 7.5. Perhaps I need to read a bit more on the vac advance.
OK 1. Set at tickover for 7.5 degs. 2. Continue to point strobe and increase revs. You'll see the timing advance as the revs increase. At approx 3,000rpm the timing will stop increasing and sit at (hopefully) 28 degs. If you find it stops increasing at 32 degs (for instance) you know it's 4 degs out. 3. let the revs fall back to idle and adjust it by 4 degs. 4. Rev again to check it now stops advancing at 28 deg The reason for checking you have the full advance figure right is because otherwise your engine may overheat, damage pistons, etc etc. when you're driving. It doesn't matter if it causes a lumpy idle or whatever, because that won't hurt your engine. What you'll probably find is that it'll be right both at tickover and full adavance, but it's best to check. Don't try and move the distributor at 3000 rpm, you might get hurt - less so on T4 engines, but on a T1 engine your hand will be perilously close to the fan belt - not recommended.
The reason I time it for max advance is to take account for the fact that the engine and dizzy are 30 odd years old. Stuff wears and the advance mechanism can't be at the same tolerance than it was when new. Even more reason if its a 'new' dizzy ie poor quality. Best to play it safe. Zeds right that if everything's good you'll find that setting it at 28 degrees will be exactly the same as 7.5 degrees. But you must check max advance.
Are you guys talking about redaing the timing witbout the vacum attached? Because my max timing is 44 2l gd engine with dual solex carbs. Timing at idle is between 6-8 worn out distributor or maybe need some lube?
Are you guys talking about redaing the timing witbout the vacum attached? Because my max timing is 44 2l gd engine with dual solex carbs. Timing at idle is between 6-8 worn out distributor or maybe need some lube?
Thanks to all above Markpc and zed. Really helpful stuff as I'm doing my Beetle and my Bus this weekend.
