MR2 Roadster Owners Club

How To: Adjust valve clearances and time the cams
by Carolyn
Pending details and pics
THIS IS NOT A JOB FOR A TOTAL BEGINNER.  YOU NEED ADEQUATE TOOLS AND A DECENT LEVEL OF SKILL FOR THIS ONE.

If you think the top end of your engine is too rattly and you want to quiet it down:

I'd start by changing the chain tensioner.  (This is covered in another 'How To').  They do get old and worn.  It can make a massive difference to top end noise at low rpm.

If you're still not happy, you will have to measure all your valve clearances and note them down.  Remove the cam cover and measure the gaps when the cam lobes are up.  This is fiddly.  Helps to have a couple of sets of feeler gauges so you can measure each one twice without having to fiddle with changing feeler blades.   You'll have to rotate the engine to measure them all.  I use a short 19 mm socket and ratchet on the crank, but you can use the 14 mm bolt on the centre of the vvti hub or, if you have room, put it it high gear and roll using the rear tyre.  Rotate clockwise (removing the spark plugs makes rotating and positioning a lot easier). Make up a 'table' for noting gaps and (later) bucket thicknesses.

• Put the engine to TDC on #1. (Cam lobes up on inlet and exhaust on #1).  You'll need to clean off the marks on the bit that sticks out from the timing cover.  I find it helps to mark the notch on the pulley with an engineer's white pen (which will also be handy for marking the chain and sprockets).

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•   Mark the chain and a tooth on each cam with the engineer's pen. Mark the horizontal timing marks on the sprockets.
• Remove the chain tensioner. 
• There's a cast-in hexagon halfway along each cam, they are there so you can hold the cam steady with a big spanner. Using the Hexagon, hold the exhaust cam steady while you undo the bolt that holds the sprocket to the cam.  Take the sprocket off.  You can let the chain drop in its guides.  You can't loose chain position on the bottom sprocket...There's a casting in there to prevent that.
• Unbolt all the cam bearings.  Keep them in order (they are numbered just in case).  The big double bearing at the front is #1 and they count back from there. (e2, e3 etc).
• Once the cams are loose, lift the inlet cam, slipping the chain off as you go.  Now lift the exhaust cam. 
• One-by-one lift the buckets and measure with a mic.  (I clean the oil off each bucket as I measure and write the measurement on the bucket with a marker pen.)  Keep the buckets in order.  Now figure out how much you need to adjust to hit target clearance,  (.20 mm inlet and .30 mm exhaust.)  For instance, you've measured a .35 gap and you want .30, so you need a bucket that's .05 thicker.  The buckets have numbers on them on the underside.  Say you have #42 and you want a .05 thicker bucket, you'll need a #47.
  You'll be able to move some buckets to new holes and you'll need some more (usually 3 or 4) to end up with a set that gets you very close.
• Ask whoever is holding the bucket bank for the club  nicely to send buckets you need.  Return any you won't be using. .  It helps if you clean the buckets and write their actual value on them.
• Once you've got the right buckets in the right holes, put the cams back in.  Make sure you put the chain over the VVTI hub as it goes in.  Make sure the cams are sitting with the horizontal timing marks level with the top of the head.
• Bolt the cams down.  Go slowly and in a bit of a 'sequence' as you'll be compressing springs. 
• Use the spanner on the hexagon to position the cams precisely.  They will have moved a bit as you've bolted them down.
• Position inlet cam first, both with the chain marks and the horizontal timing marks.
• Put the exhaust sprocket into the chain, aligning the chain mark to the sprocket tooth, and offer it up to the front of the exhaust cam, again positioning the cam with the big spanner.  Bolt the sprocket back on to the cam.
• Re-install the chain tensioner.
• Using the bolt in the middle of the bottom pulley, rotate the engine clockwise until the tensioner releases. 
• You can then rotate the engine 720 degrees and check the horizontal timing marks against TDC on the pulley.
• The chain marks won't now be in the same position (that's ok)
• If all is still timed up, give it all a good squirt of engine oil and put the cam cover back on.

Don't even ask about the chain!!!

This pic shows a timing issue. The engine is at TDC correctly but the timing marks on the insides of the sprockets are not lining up exactly. This needs to be fixed so that they line up, before you continue

(https://uploads.tapatalk-cdn.com/20180919/fe183a5a6a69c43759001c49a18c1a3e.jpg)

This shows correct timing. Engine at TDC again but this time the dots line up perfectly.
The fact that the chain markers don't align at the top doesn't matter to timing.  You can see the cam lobes on #1 cylinder are both up and pointing at each other.  This means the engine is at TDC on cylinder #1. (Which is the correct position.

(https://uploads.tapatalk-cdn.com/20180918/bc12ba59dbf7718d74f3a0bb2794af4b.jpg)

(https://uploads.tapatalk-cdn.com/20180919/0915c1453f7de02e28cfc78315bcd01c.jpg)

Also attached is a pic of using an adjustable spanner on the camshaft.  This is important for both tightening and positioning.