Timing chain alignment

Post by **southerly95** » Sat Jul 21, 2007 12:44 am

How can I re-check that the timing chain is correctly aligned after a rebuild without having to strip the front end down again please? Many thanks, John

Post by **kennatt** » Sat Jul 21, 2007 11:04 am

if you mean you want to check the timing take off the rocker cover and take out spark plugs.turn engine over and watch the rocker arms on no 4 cylinder (the back one).When the exaughts and inlet are rocking (Ie both moving up and down when you turn the engine back and forwards)then the piston on one should be at the top (Check with a soft probe into the pulg hole)Move the engine back and forwards with the probe inside the plug hole to find out when the no one piston is at top dead centre.Then check that the rotor arm in the distributor is pointing at the terminal for no one spark plug. Then check to see if the timing mark on the bottom pully is in line with the timing mark on the casing.If it is then the timing is basically correct.and therefore timing chain is correctly fitted. IF its a mile out then off with the front covers and re fit to correct timing marks on the cam wheel crank shaft.

Post by **bmcecosse** » Sat Jul 21, 2007 1:09 pm

Alignment can only be checked with the timing cover off - use a straight edge across the edges of the two chain sprockets to determine if correctly aligned. If not - add shims behind whichever sprocket is behind. It's worth checking the end float of the camshaft - I found an engine that had almost 3/16" endfloat due to incorrrectly machined cam sprocket.
If it's valve timing that's worrying you - then it's a bit more complicated than listed above! You will need a dial gauge indicator and stand - basically - at TDC both the inlet and exhaust valve should be open by exactly the same (small) amount. If one is open more than the other - then the valve timing is not correct. So - you first need to very accurately determine TDC using the dial gauge on a piston crown (can be done down the spark plug hole) - and then you need to accurately measure the valve lift on both the valves at TDC.
Why do you think there may be a problem - and is it 'alignment' or 'timing' that's concerning you ?

Post by **southerly95** » Sat Jul 21, 2007 4:36 pm

Thanks for replies. I'm wanting to check whether I have put the timing chain on the sprockets correctly, not the alignment of the sprockets with each other's faces which are ok.

I have done the checks in the first reply - cover off, no 4 valves rocking and no 1 at tdc BUT the pulley notch is not at the pointer on the timing case but 180 degs out and pointing skywards not earthwards! The tail of the rotor arm is closest to no 1 plug outlet.

Please advise, thanks, John

Post by **southerly95** » Sat Jul 21, 2007 4:50 pm

I'm wondering if the rotor arm should be at the beginning of the no 1 electrode position not the end - when at tdc on no 1?

Post by **aupickup** » Sat Jul 21, 2007 5:11 pm

sounds like its 180 out, so 4 piston will be the firing one and rotor arm pointing to that

i had this on a minor, but ran the same so i kept it like it

Post by **bmcecosse** » Sat Jul 21, 2007 5:16 pm

Makes no odds being '180' out. That's not the worry - concern is if you have put it on 1 tooth out on the timing - the car will not run too well like that! But surely you would have checked and double-checked that before locking up the tab washer on the cam sprocket.

Post by **kennatt** » Sun Jul 22, 2007 8:54 am

the tapered bit of the rotor arm the bit with the brass tab, points at the terminal that it is about to fire the charge down to that coresponding plug lead and then to the plug.Turn the engine over in the correct direction of rotation.and watch ANY pair of valves. watch for the exhaust valve to open and close watch for the inlet valve to open and close then using the probe make sure that the same piston is at top dead centre. Then look at the rotor arm if the timing is correct the brass tab on the tapered end of the rotor should be pointing at the terminal than corresponds to the lead that would go to that same cylinder be it 1 2 3 or 4. If you have watched no 2 and the rotor is pointing somewhere else(Just before or just after can be sorted by moving the distributor) like at no 3 or between terminals then you have got the basic valve timing wrong.and need to re time on the cam shaft and crank sprockets. Its easy to get it wrong as bmc says you should always check and double check before closing everything up. Don't worry we have all done it at sometime. At least it's not a twin overhead cam with no timing marks as most modern cars are.Easy to sort out. Good luck

Post by **bmcecosse** » Sun Jul 22, 2007 9:51 pm

The IGNITION timing can be set anywhere you wish - just turn the dizzy to suit. The position of the rotor arm has nothing directly to do with valve timing - you can move the drive spindle round if necessary. But VALVE timing must be checked as I have already detailed.