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TDC and rotor arm position

36 posts in this topic

Hi all,

I have changed the aftermarkt electronic distributor on my 1979 xd Fairmont with a Bosch one and am now trying to get the timing/tdc set.

There are no marks on the harmonic balancer that I can see so have used the 'thumb over the no.1 spark plug hole' method and have moved the rotor arm around to face the no,1 cylinder (as I thought was correct?) but all it now wants to do is spit flames out of the carb when I try to start it!

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Having searched on the internet it seems that I am setting the distributor/rotor arm in completely the wrong place and that it should be facing roughly to the firewall or slightly towards no.8 cylinder?

HELP!!!!!

Outback Jack likes this

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you can face the rotor arm anywhere you want.. as long as it lines up with the ignition lead going to number 1 spark plug(when you have tdc compression on number 1) lifting the rocker cover off and checking the rockers are both not moving at all on number 1cyl will be a closer setting(by eye/ear) (fully closed valves ready for ignition to fire)

i set one last week and pointed the rotor to the vac advance vac line .. spark plug post is above it.. run that to number one lead and it was fairly close.. in the tdc position.. 
 

 

```, Lott and bear351c like this

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For reasons of neatness, i set up #1 at or above about 9 o'clock so #3 will be next to it at about 7 o'clock.

 

13726548 is the firing order, anti-clockwise rotation.

 

Set the rotor at 9 o'clock or as close as the drive gear teeth will allow. Drop the dizzy into mesh and bump over the engine until the dizzy pops all the way down when the oil pump shaft engages. You might get lucky and have it line up anyway.

 

Rotate the dizzy body so that when you put the cap on, it lines up with 1 or just after. You can determine the actual trigger point for spark if you look at the reluctor teeth and see where they line up.

 

If you were close to piston tdc, it should be sitting at around zero, which should fire. Then wind the dizzy clockwise to advance to whatever timing you're going to run. The plug leads should be reasonably symmetrical.

 

To double-check before starting, turn crank back round to #1 compression. Put all leads on except #1, get a spare spark plug and shove it in the terminal, grounded to the engine. Turn on ignition. With the dizzy still loose, rotate the body back and forth quickly to see where it triggers the spark. You'll get an idea of what angle the dizzy needs to be so you can lock it down and at least get it firing.

 

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just stick a long screwdriver or wire down no 1 cyl and wind it over by hand  until it stops and hovers a bit that will be rough tdc,make sure your on the compression stroke,like the boys said it dont matter where the pointer is as long as its on no 1 lead,then adjust your dizzy a little advanced and it should fire up,then properly time it with the light,it sounds like your on the exhaust stroke if its backfiring and spitting out the carby.

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Vacuum can should point straight ahead. As said, doesn't matter which way the rotor is situated, just make it no.1 lead on the cap, and go anticlockwise with the rest. Sounds like you have it 180* out. IE: not on the compression stroke. For absolute check, pop off the left hand rocker cover and see if the valves are up or down, pushrods should spin with 2 fingers. Don't trust the harmonic balancer. Once you've established TDC, mark it with a white marker, or file.

 

That dizzy looks like new.! 

``` and Outback Jack like this

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If I am hand cranking the engine over..which way am I turning it as you look at it from the front..clockwise or anti-clockwise?

I am going to pull the rocker cover off and try to get the tdc more accurate.

Outback Jack and CHESTNUTXE like this

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Just now, deankdx said:

Clockwise if you are facing the engine from the front of the car. 

cheers for that..might seem an obvious, simple question but having never done it before didn't want to risk any possible damage!

Outback Jack and deankdx like this

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As a general convention, nearly all engines turn clockwise from the "front" ie from the opposite side to its "flywheel" side. There are exceptions but very few. Some aero and marine engines can be configured to turn backwards for balancing out twin setups.

Your useless info for the day (you're welcome)

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Outback Jack, ```, stockesp and 1 other like this

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or a 351c with 302c heads running on crap fuel turns backwards when turning the key off:angry:sounds like a kangaroo going thru a mincer

``` likes this

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or a 351c with 302c heads running on crap fuel turns backwards when turning the key off:angry:sounds like a kangaroo going thru a mincer
Lol I can vouch for that but on an LPG crossy. If you crank and it doesn't kick straight away, you'd get a horrible squeal out of the mixer (the backfire valve popping open) and a puff of oil smoke out the air cleaner.

Just think, an oil pump spinning backwards isn't pumping oil, it's sucking it back out of the filter

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CHESTNUTXE likes this

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If I am having to turn the dizzy all as far as is possible clockwise to get it anywhere near running right is the dizzy in the wrong place?

To my untrained brain I am thinking it may be a notch out of alignment..if that's correct, which way do I turn one notch, clockwise or anti-clockwise?

First pic is of it turned as far as it can go (vacuum at roughly 7 0'clock) and second one is of it with the vacuum pointing to the front (roughly 6 o'clock).

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Doesn't matter.  If no.1 cyl is on true TDC, then leave the vac advance at 6 o'clock, then 'spiky wheel' in the dizzy should be lined up with one of the spikes on the outer ring. Make that Number 1 spark lead. Then anticlockwise 1-3-7-2-6-5-4-8. Try not to run no.6 and 5 leads parallel to each other, as they can crossfire. Lead separators are cheap enough, or a couple of cable ties to hold them apart. 

Outback Jack and CHESTNUTXE like this

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those fkn vac units always get in the way of trying to get enough advance in it on a clevo,there is a sweet spot with the cam and oil pump drive all lining up spot on,keep playing with it you will get it in the end.

Outback Jack likes this

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another trick to get a few more mm out of it is to use a xy/xa style straight water neck gives a little more clearance.

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Vacuum can should point straight ahead. As said, doesn't matter which way the rotor is situated, just make it no.1 lead on the cap, and go anticlockwise with the rest. Sounds like you have it 180* out. IE: not on the compression stroke. For absolute check, pop off the left hand rocker cover and see if the valves are up or down, pushrods should spin with 2 fingers. Don't trust the harmonic balancer. Once you've established TDC, mark it with a white marker, or file.
 
That dizzy looks like new.! 
Read.... read again... rinse ... repeat.... read again.... hehe.

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CHESTNUTXE likes this

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14 hours ago, bear351c said:

 then 'spiky wheel' in the dizzy should be lined up with one of the spikes on the outer ring.

So this is how I had it set up but, as I say, had to turn the dizzy as far clockwise as I could and vacuum ended up at 7 o'clock ish.

If I am understanding you right, I need to lift the dizzy out enough to rotate it (anti-clockwise?) and line the two sets of spiky wheels up then set the new position of the rotor arm to no.1 plug lead and the rest to follow?

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bear351c likes this

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Yep, just like that....... Lift the dizzy about an inch, twist it left or right and re-insert. Make sure you're at TDC and the harmonic balancer should be around where you set the timing. 8-10 deg BTDC. Then the spikes will line up, and wherever the rotor is make that No.1 spark lead, then add the rest anticlockwise. 

Outback Jack and ``` like this

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Ok..managed to get the dizzy spikes lined up and have relocated the plug leads to correspond.

Will have to give it a crank over in the morning as the other half is in bed as she works nights and will not be popular if I wake her up!!

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On 10/20/2017 at 5:26 PM, bear351c said:

For absolute check, pop off the left hand rocker cover and see if the valves are up or down, pushrods should spin with 2 fingers.

Still faffing about with this:angry:

Which pushrods are you referring to..just the front two?

bear351c likes this

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No.1 cylinder. First one on the left hand side head, standing in front of radiator. If it's on TDC, both pushrods should be easily rotated with your fingers.

Outback Jack and gerg like this

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