13 replies to this topic

[Bradley Gaunt]

Been busy building my new engine and after torqueing up the flywheel and hence being able to turn the engine over by hand, I noticed a clunking noise from the timing side of the engine. After taking the cover back off I can see that the 2 sprockets arent in line and the clunking is the chain hitting the teeth of the cam sprocket because it isnt running true. I pulled the crank sprocket away from its hard up position against the crank so it was more inline with the cam sprocket and the clunking stopped.I had the half engine assembled by the company that did the new offset bore on the block and would have thought they have set it up correctly... is there something I am missing or is a simple case of it should be shimmed? I must add that the timing gear and crank had come from a previous block and were ok then, the cam shaft is new though.

[Cooperman]

You simply use shims to get the sprockets in line. They are normal parts and are obtainable from most Mini engine parts suppliers. Use a straight edge across the sprocket faces with the chain removed to ensure alignmrnt.

[bmcecosse]

Sounds like they were a LOT out of line...... shims should only be a very few thou. Is the cam installed correctly? Triangle plate right way round? Cam securing nut tightened fully? How much end float is there in the crankshaft??

[Pigeonto]

Had a horrible thought there for a minute they may have put the crank sprocket on the wrong way round? no,surely no one would be so daft,but then you wouldnt see the timing mark and the chain would be miles out of straight. May be talking rubbish and not even possible to do.Something's amiss obviously

[Bradley Gaunt]

I'll check the sprocket isnt on wrongly but fairly certain it is on correctly. When the pully bolt is tightened would it push the sprocket up hard against the crank or is it stopped some other way and the timing sprocket is floating? The distance out is 2 - 3 mm

[lrostoke]

That seems a fair bit out, have you tried using a large socket and knocking the sprocket on as far as it goes. Pretty easy check if on the right way round, on the outward face there is a dot punched next to one of the teeth. Will be same on the cam sprocket these are the alignment marks.

[Bradley Gaunt]

Turns out the engine builder had fitted the cam sprocket the wrong way around, I carefully turned it over and re assembled and it lines through. When I flipped it over and refitted I had to move the dowel by about 1.5 - 2mm so it would relocate, is this going to throw the timing out? Also what lock tight should I use on the cam nut as it was lock tight in position and dint have the locking tab knocked over - on previously asking the builder why the tabs werent knocked over he said that he didnt trust them as he had seen them fail in the past.

[lrostoke]

The sprockets should be aligned using the dots if they are just standard sprockets and no a special cam or anything.
Crank srocket dot should be at roughly 1 oclock, cam sprocket dot at roughly 7 oclock.
When you put a straight edge across the center line of the crank and camshaft, the dots should be in a straight line with those center lines.

[Bradley Gaunt]

The sprockets should be aligned using the dots if they are just standard sprockets and no a special cam or anything.
Crank srocket dot should be at roughly 1 oclock, cam sprocket dot at roughly 7 oclock.
When you put a straight edge across the center line of the crank and camshaft, the dots should be in a straight line with those center lines.

I know what you mean but in my haste to flip it over i forgot about the dots but it is a dowel type adjustable vernier so it shouldnt make any difference to the timing so long as during the flip neither the crank or cam moved which they did not. All I was meaning was that when relocating the dowel it needed the cam turning 1.5 - 2mm for the dowel to locate. Should this small amount cause any issues? Also is there a method for fitting the chain tensioner as I could have it very slack or quite tight?

[dklawson]

You have the vernier timing pulleys? Yes, flipping the parts over after they were dialed in by the engine builder is going to change the valve timing.

You could contact the builder, explain what you found, and tell him you want to bring the engine back to him to have him reset the valve timing. However, he could say this is now your fault because the parts have been removed. If you have your own DTI and degree wheel you can set the valve timing yourself if the builder refuses to help. Regardless, you need to check and readjust the valve timing before finishing the engine.

[lrostoke]

Not sure I'd be trusting the engine builder , if he managed fit the sprocket wrong in the first place, surely he noticed the chain out of alignment, that would have triggered alarm bells as it did with yourself.
What other work as he done ???

[Bradley Gaunt]

He has offset bored the block fitted new piston rings, all new bearings on crank and cam shaft, new cam shaft, centre main strap and assembled it as a half engine.. alarm bells are ringing but have it on the box now and wouldn't know where to start to check his work, he came highly recommended from this forum and makes regular posts so had a lot of confidence in his ability.

[Pigeonto]

One other thing occurrs to me.Chain wheels are actually quite soft and if the side plates of the chain try to ride up the teeth of the sprocket they can cut in and lift metal off the sprocket.This would be a huge problem waiting to happen so I would be checking all the teeth closely

[Cooperman]

You definately need to re-time it properly with a DTI and a crank protractor.