timing weirdness.

[ari666]

ok i am scratching my head here. i mean REALLY scratching my head here.

the other day was tuning sabbathss's VH and was setting the timing. had the light on while sabbath cranked and the timing mark was lining up perfectly @ 12BTDC, but the engine was coughing and spluttering as if the timing was 180 out.

after draining whole battery and checking EVERYTHING i finally decided to bite the bullet and spin the rotor around 180. to which it fired immediatly...

now that its the right way round the mark is set solid on 12 deg, just runs beautiful, plenty of power and managed to get a good vac reading.

so.... how the fek is it possible to have the timing mark light up on 12 degrees if its 180 out???!!!??? i checked the whole balancer, its a romec steel balancer and has markings all the way round to 180, it hasnt spun and i tried 2 different test lights.

got me stumped. if its 180 it should light up on the other side of the balancer.. right?

[soop]

Sure u werent being a herpa and looking at the negative indicator?

[ari666]

nope 0 TDC marked on it, then 180 for the other side

[Zeussy]

Doesn't the dizzy run off the cam, at half speed of the crank?

[soop]

the Dizzy isn't in backwards is it?
If its in backwards and someone has reversed the leads to compensate it will do that.

[Zeussy]

Let me elaborate,

Cam turns one turn - crank turns two turns,
Cam turns half a turn, crank turns one turn,

Dizzy/cam can be 180 out - crank still in same position,

So, its one full turn of the crank out, but only half a turn of the cam?



EDIT:
Theres two points when the #1 piston is at TDC, a compression - combustion/ignition stroke, and a exhaust - intake stroke.
You probably had the dizzy firing when it was pushing out the exhaust, not when compressing the air fuel...

[ari666]

lol, makes perfect sense. i am such a dumbshit. lol. for the longest time i thought that by using the light itll sho on the balancer that you are 180 out...

thanks man... (now how do i delete all traces of me asking this question?)

[Zeussy]

lol, thats cool, didn't mean to sound like it was a stoopid question man, I was half sort of tripping about whether it was infact the cam that the dizzy ran off..!
Its been too long since I've played with internals... Was a bit tired too!

Its all good I'll be asking quite a few stoopid Q's when it comes to these 5L's. Regarding performance, basic problems etc... I'm sure you have a lot more knowledge on them than me!