hairyone Posted March 2, 2007 Share Posted March 2, 2007 Having recently won a nice snap-on timing light on ebay I decided to put it to good use and see what my timing actually was, up until now I have done it by ear and backed off a little from pinking. I was rather surprised to find that it was 26deg advanced at 2000rpm (with vac disconnected) and 15deg at idle). Now the book says it should have been about 16 degrees. Since I had changed the timing chain last year I guessed that the most likley cause was the chain was one tooth out (40 teeth so one tooth = 9deg). Last night I stripped it down and took off the timing cover and I was quite surprised to see that the 'P' mark on the camshaft was 180deg out (ie from the 11o'clock bolt hole). The crankshaft was at TDC according to the pulley (woodruff key on crank pointing to 12o'clock as well) and the dizzy was point at no1 lead (which peering into the cr from the drivers side was about 1'oclock). Now when I changed the timing chain I took great care not to move the camshaft and crank until I had the new chain on (I have to confess I left rad on) and assumed that every thing could just be slipped back on, I might have been 1 tooth out but not 180deg. I had to readjust the dizzy a small amount (I assumed this was necessary because the old chain had probably stretched a little). but the car appeared to run fine and I have done hundreds miles since. The starting was always a little sluggish (needed a bit of choke), and sometimes I felt that it was a bit hesitant but no major worries. Anyhow last night I spun the camshaft a few times trying to work out why it was 180deg out, but each time as the dizzy approached sparking on the no1 lead, the 'P'mark wasabout 180deg. Since I couldn't work out what was going on I just readjusted the chain by one tooth (it was out, if you ignored the 180deg out prob) and then reassembled. After adjusting the dizzy I got her started but the timing reads about 16deg advanced at idle. This morning I started her from cold and got her running with no choke (previosly this would have been impossible). So the big question is why does it run with the c1am 80deg out, has the dizzy drive dog been rotated 180deg out in the past, I'm totally lost for ideas. I was not keen to just set the cam by the book coz it would have left the dizzy pointing at no4 lead at TDC. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2007 Share Posted March 2, 2007 The 'problem' isn't your cam or crank, but the dizzy. The camshaft turns once for every two ratations of the crankshaft, so it only seems to be 180deg out because you are using the position of the rotor arm as a reference, instead of the other way round. If you set the crank at TDC with the camshaft timing mark in it's correct position, the rotor arm will be 180deg out. Lift the dizzy about 1/2" and turn the rotor arm so that it is in the firing position for No1 cylinder. Set the static timing and then use your strobe light to get it correct. Hope you were referring to the 2.25 engine Les. Quote Link to comment Share on other sites More sharing options...
hairyone Posted March 2, 2007 Author Share Posted March 2, 2007 The 'problem' isn't your cam or crank, but the dizzy. The camshaft turns once for every two ratations of the crankshaft, so it only seems to be 180deg out because you are using the position of the rotor arm as a reference, instead of the other way round. If you set the crank at TDC with the camshaft timing mark in it's correct position, the rotor arm will be 180deg out. Lift the dizzy about 1/2" and turn the rotor arm so that it is in the firing position for No1 cylinder. Set the static timing and then use your strobe light to get it correct.Hope you were referring to the 2.25 engine Les. Thanks for the quick reply Les, that makes sense. At 2:00 am last night it was all starting to get a bit fuzzy, especially since my morning alarm goes off at 4:45am . The only problem I can see with that it would place the vac advance between the dizzy and the engine block, also the dizzy has an offset slot to drive the rotor shaft, so I'm not sure how you can only rotate it half a turn. I'm not sure if it makes a difference but it's a 2.5 petrol. I'm sure it's just a matter of geometry, is it possible that someone put the dizzy drive cog into the block 180deg out (the engine was reconditioned before I bought the car)? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2007 Share Posted March 2, 2007 The distributor body doesn't get turned, just the shaft that the rotor arms is located on. Set the cam and crank to their respective timing marks. Slacken the distributor pinch bolt Lift the distributor up a small amount (1/2" or so) Rotate the rotor arm 180deg Locate the distributor back in the engine block. You'll notice that as the distributor slides back down - the shaft turns slightly. You have to allow for this in order to get it in the right position. Les. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2007 Share Posted March 2, 2007 Just noticed you have 2.5 petrol, I was referring to the 2.25 engine. In that case all I can think of doing is put the timing in the right position, and then re-position the plug leads. Les. Quote Link to comment Share on other sites More sharing options...
rtbarton Posted March 2, 2007 Share Posted March 2, 2007 Be careful with those electronic strobe lights. Mine showed an advance of about 30 deg, the engine ran perfectly and when I set it up to the lamp it would run like a bag of nails. I put it down to the sensitivity adjustment on the lamp, if set too sensitive it can go off early. Quote Link to comment Share on other sites More sharing options...
hairyone Posted March 2, 2007 Author Share Posted March 2, 2007 The distributor body doesn't get turned, just the shaft that the rotor arms is located on.Set the cam and crank to their respective timing marks. Slacken the distributor pinch bolt Lift the distributor up a small amount (1/2" or so) Rotate the rotor arm 180deg Locate the distributor back in the engine block. You'll notice that as the distributor slides back down - the shaft turns slightly. You have to allow for this in order to get it in the right position. Les. Understood Les, But I'm sure that the rotor shaft is driven not by a helical gear on the end but a "dog drive" i.e. the end of the shaft has a blade like a screw driver that fits into a corresponding slot on the drive gear. Both the slot and blade ar offset tow one side like this (looking at the end of the distributor (bad ascii art") ..... / ||\ | O|| | \ ||/ '''''''' The way I picture it, the rotor shaft will only fit into the hole in a single orientation. O.T.O.H maybe I could lift out the slotted gear that sits on top of the skew gear. I've got a pic from the manual that show what I mean but can't seem to upload it. But based on what Les has said everything is Ok just 180 deg out, if I can flip the dizzy drive thru 180 it will look OK according to the book. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted March 2, 2007 Share Posted March 2, 2007 We cross-posted there. Just re-position the plug leads with the dizzy in it's current position. I assumed you were asking about a 2.25 engine. Les. Quote Link to comment Share on other sites More sharing options...
hairyone Posted March 5, 2007 Author Share Posted March 5, 2007 Just another thought... Now that I'm now happy that my dizzy is just sitting 180 degrees out. The advance dial on the snap-on timing light MT1241, does the advance dial show engine degrees of advance? If I'm dialing 16 degrees on the timing light at idle to zero the pulley marks with the pointer does that mean that I've adjusted the dizzy to give 8 degrees of static advance (i.e. vac disconnected, an no mechanical advance at idle). I think I might have just been confused by the LR manuals giving the dynamic advance figures in distributor degrees. Quote Link to comment Share on other sites More sharing options...
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