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Top Dead Centre
Posted: 11 Apr 2010, 13:40
by albertramsbottom
How do i know when my van is at tdc?
I can see the plastic deg scale on the fly wheel but cant seem to see any tdc mark or am i looking in the wrong place?
Anyone tell me where is should be? I need to do this as my van isnt starting and I need to check that all my leads are on right and that the rotor arm is on or just before cylinder one at TDC.
My van is popping up it sounds odd, like the firing order is wrong.
I tried a screw driver down the spark plug hole but it just got stuck
is it posible with some sort of test light?
Thanks people for all your patience
Re: Top Dead Centre
Posted: 11 Apr 2010, 14:17
by dj biz r
try removing plug no.1 plug in a wine cork as you turn engine by hand it should pop out at compression stroke,look at wheel is it the mark,lined up with case split also is rotor now pointing to lead 1 position? you can put pencil or simular in hole if no cork but remember the piston has too up moves .i tried test lamp which is spossed to light as you pass ignition but alas my light stayed on showing nothing.good luck
Re: Top Dead Centre
Posted: 11 Apr 2010, 14:25
by albertramsbottom
dj biz r wrote:try removing plug no.1 plug in a wine cork as you turn engine by hand it should pop out at compression stroke,look at wheel is it the mark,lined up with case split also is rotor now pointing to lead 1 position? you can put pencil or simular in hole if no cork but remember the piston has too up moves .i tried test lamp which is spossed to light as you pass ignition but alas my light stayed on showing nothing.good luck
Sorry what do you mean by "look at wheel is it the mark lined up with case split"
If you mean the TDC mark on the flywheeel well I cant seem to find it
Cheers
Re: Top Dead Centre
Posted: 11 Apr 2010, 14:46
by dj biz r
sorry ,yes on my flywheel i,ve got a ding mark on inside lip and another on outside lip one being tdc one being before tdc .and im referring to where the two crank case halfs join im going on the assumption yours will be same ive got 1.9dg wbx
Re: Top Dead Centre
Posted: 11 Apr 2010, 15:39
by albertramsbottom
Cheers for that - I have a Aircooled CU and I cant see any marks on the flywheel at all
Cheers
Re: Top Dead Centre
Posted: 11 Apr 2010, 16:26
by dugcati
Try using the screwdriver again but hold it into the center of the bore - it got stuck because you put it into the hole then let go of it then turned the engine so it jammed up.. you might be best with an assistant
Re: Top Dead Centre
Posted: 11 Apr 2010, 17:38
by Red Westie
The most accurate way of setting TDC is to use a dial test indicator and spark plug adapter and then mark zero (TDC) on the pulley.
Martin
Re: Top Dead Centre
Posted: 11 Apr 2010, 17:48
by albertramsbottom
Red Westie wrote:The most accurate way of setting TDC is to use a dial test indicator and spark plug adapter and then mark zero (TDC) on the pulley.
Martin
Whats that then?
Re: Top Dead Centre
Posted: 11 Apr 2010, 17:56
by albertramsbottom
Thnaks folks but no one has told me where the TDC mark should be on a CU engine
Cheers
Re: Top Dead Centre
Posted: 11 Apr 2010, 19:05
by VWCamperfan
Same as mine. Got a CT engine but I know it's the same for yours. It's on the crankshaft pulley. If you follow the ignition lead from your number 1 spark plug to the distributor, remove the dizzy cap and turn engine until rotor arm is where the number one lead went into the dizzy cap. You may then find the notch a little easier on the pulley wheel. (If leads etc. are in correct position!).
Re: Top Dead Centre
Posted: 11 Apr 2010, 19:27
by VWCamperfan
Should add...
The screwdriver trick can work but you may not be at TDC on the compression/ignition stroke. You could be TDC on the exhaust/intake stroke which would look like your rotor arm is 180 degrees out.
Easiest way to find TDC is to loosen No.1 spark plug a few turns, put van into top gear and push forward until you hear air pushing past the plug. You then know you are on the way to TDC. Keep going until no more air can be heard coming out and your TDC mark on the pulley should be just past the zero mark on the scale. You will also be able to see where the rotor arm is etc.
Re: Top Dead Centre
Posted: 12 Apr 2010, 08:34
by albertramsbottom
Thanks for all the help
However, if I had a TDC mark on the pully I would know where TDC is but I dont or I cant find it.
Thats my problem.
Cheers
Re: Top Dead Centre
Posted: 12 Apr 2010, 08:46
by jamesc76
albertramsbottom wrote:Thanks for all the help
However, if I had a TDC mark on the pully I would know where TDC is but I dont or I cant find it.
Thats my problem.
Cheers
And every one is telling you how to find it with out a mark! Find it then put your own mark on it ! I build massive engines at work (bloody huge) and untill your 75% built it theres no timing marks and we mark our own!
Re: Top Dead Centre
Posted: 12 Apr 2010, 09:45
by Red Westie
I know this link is for a Yamaha RD400 engine but the priciple is just the same...
The most accurate way of 'SETTING' and 'MARKING' TDC on the pulley is to use a Diat Test Indicator and spark plug adapter, which can be fashioned from an old spark plug if needs be or atherwised machined from ally bar.
Fit to No1 cylinder, slowly rotate the engine until the DTI starts to rotate, carefully move back and forth until you get the point at which the gauge changes direction (TDC) mark pulley......I would even recommend this for anyone wanting ACCURATE marks and not just factory settings (blue print) bob on.
Just make sure the rotor arm points to No1 (notch in the rim of the distributor) to ensure you haven't got the crank 180degrees out.
See:
http://images.google.co.uk/imgres?imgur ... s%3Disch:1" onclick="window.open(this.href);return false;
I will take a pici of my gauge and post it soon.
Martin
Re: Top Dead Centre
Posted: 12 Apr 2010, 09:52
by albertramsbottom
Red Westie wrote:I know this link is for a Yamaha RD400 engine but the priciple is just the same...
The most accurate way of 'SETTING' and 'MARKING' TDC on the pulley is to use a Diat Test Indicator and spark plug adapter, which can be fashioned from an old spark plug if needs be or atherwised machined from ally bar.
Fit to No1 cylinder, slowly rotate the engine until the DTI starts to rotate, carefully move back and forth until you get the point at which the gauge changes direction (TDC) mark pulley......I would even recommend this for anyone wanting ACCURATE marks and not just factory settings (blue print) bob on.
Just make sure the rotor arm points to No1 (notch in the rim of the distributor) to ensure you haven't got the crank 180degrees out.
See:
http://images.google.co.uk/imgres?imgur ... s%3Disch:1" onclick="window.open(this.href);return false;
I will take a pici of my gauge and post it soon.
Thanks for that red westie
I think you are right insofar as if I gonna do this then I should do it properly. Just cant figure out why there anit a mark there already. Dont suppose there is one on the flywheel at the front of the engine (looking through the little round hole in the tinware.
Im going over to have another look
Cheers
Martin
