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what would cause my ignition timing to be 180 degrees out?


EarthwurmJurm

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I checked my timing tonight as I am trying to cure a pesky misfire, and as far as I can tell it is a full 180 degrees out ! :o

Thing is the motor seemed to be running alright when I first put it in the car (fiat 1800 twincam) but it's hard to say since it was just at idle in my garage, it's developed the miss (quite a bad one !) since I have been road testing it etc.

why would my timing go that far out? or am I just being a noob ? :o

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The dissy and cam must be in the right relationship to each other or else it wouldn't start, if the dissy was 180 out from the cam then the compression stoppers (spark plugs) would be firing when the motor is in suck stroke instead of bang stroke (assuming the dissy is on the inlet cam of course) If you had perhaps got your leads out of sync as well as the cam and dissy being wrong then maybe it would run...

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It happens all the time that someone puts the dizzy in 180 degrees out and then just changes the plug leads around to suit.

I am not sure how you have discovered that it is 180 degrees out though - if you are looking at set up marks on the camshaft then remember that the camshaft only turns once for every two rotations of the crankshaft.

EDIT: If both camshafts and the dizzy are 180 degrees out from the crank on a four cysinder engine (flat plane crank) then it will run just fine. The only thing to remember MIGHT be that you have to take the pulse for your timing light of the third firing piston - but I would need to think about that more first and I haven't got any beer and I can't think on an empty stomach etc.

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well after further inspection it turns out I am indeed a muppet. lol, the dizzy is driven from the crank, and turns once for every 2 revolutions of the crank, so after turning the crank another 360 degrees.. problem solved, ignition timing is spot on.

what's next you say? well I have checked the valve timing and that is all tickety boo, so I will replace and gap the points, replace the condensor, also have new leads, plugs, cap and rotor, which will hopefully cure the chronic misfire I have, if that doesn't work I will try a new coil, if I'm still not having any luck I guess I will try swapping a different carb on.. if I'm still not having any luck I guess I will whip the head off!

bearing in mind this is somewhat of a learning curve, as I'm doing all the work by myself and am by no means a mechanic, does this sounds like a good plan? techo gurus? k thx :)

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maybe idles a bit faster but the throttle linkage is pretty hax.

It sounds like it's running on 3 tbh, all the time even at idle, It was running ok for about the few minutes after I had the engine in and drove on it

the fuel is all good

Sounds like a subaru. And yeah definately 'sounds' likes its not firing on all cylinders.

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A fast idle that you can't get low enough is usually a stong sign of a vacuum leak. They are easy to test for - just purchase a can of brake clean and spray it around the inlet manifold gasket area and carb base.

If the engine almost stalls when you are spraying in one particular area that is where your vacuum leak is.

Decent plugs and leads could well solve your problem though. If not a compression test is worth doing too.

Let us know once the new points are in - removing the dizzy to fit the points is a fairly ballsy move but I assume you had a good reason

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that's alright I know more or less what I'm up to, just waiting on a condenser and a rotor cap that fit now.

Atm I'm trying to source a cheap dizzy, the one in my motor atm is a sohc one with the single points set up, it's in pretty average nick, there is a little bit of side to side play and the oil slinger has half disintergrated, I've got an ok price for a uno eltronic setup, I'm not sure if the dizzy will fit my old school twin cam however.. anyone know?

I will try the sohc one out with some new parts however and see how it goes :)

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