cam timing/ locking tool???
Discussion
I want to check my valve clearances and the tvr service schedule says you need to lock the cam/sprocket.
I have never used one of these tools before nor have I seen one. I have changed timing belts before but never messed with a chain.
do you need this tool to do the job?
or can it be done with marking positions etc?
are the tools specific to the ajp or tvr?
where can i get one from if i need one and how much?
thanks in advance.
I have never used one of these tools before nor have I seen one. I have changed timing belts before but never messed with a chain.
do you need this tool to do the job?
or can it be done with marking positions etc?
are the tools specific to the ajp or tvr?
where can i get one from if i need one and how much?
thanks in advance.
Locking? I didn't do any locking. I did need to make a retainer so I could slide the sprocket off the cam onto the retainer.
I just (carefully!) followed the instructions in the workshop manual. Roughly; you turn the engine to a specific safe position depending on which bank you are working on. Slip the sprocket off the cam onto a retainer. Then you can safely turn the cam to measure the clearances. Replace and set cam timing. Repeat for other bank.
I just (carefully!) followed the instructions in the workshop manual. Roughly; you turn the engine to a specific safe position depending on which bank you are working on. Slip the sprocket off the cam onto a retainer. Then you can safely turn the cam to measure the clearances. Replace and set cam timing. Repeat for other bank.
Edited by Tanguero on Friday 13th February 09:18
shayne, are you doing this with the timing cover removed?
if so I have a couple of bits I made up, one plate to hold the front of the bottom cam chain sprocket in place, and a cam chain tensioner, ( the cars tensioner is in the timing cover, so need something else in its place).
you are welcome to borrow them if you like.
if so I have a couple of bits I made up, one plate to hold the front of the bottom cam chain sprocket in place, and a cam chain tensioner, ( the cars tensioner is in the timing cover, so need something else in its place).
you are welcome to borrow them if you like.
Edited by clive f on Friday 13th February 08:52
what ever is easiest really.
i need to get the timing cover off for painting, so if its easier to do with it off then thats the way i will go.
if its easier to do with it on, in order to rest a tool on the cover for the cam sprockets to slide on then ill go this way.
what ever people recommend to be honest.
Thanks very much for the offer Clive, if this is the way to go then i will take you up on your offer of borrowing the bottom sprocket tool
i need to get the timing cover off for painting, so if its easier to do with it off then thats the way i will go.
if its easier to do with it on, in order to rest a tool on the cover for the cam sprockets to slide on then ill go this way.
what ever people recommend to be honest.
Thanks very much for the offer Clive, if this is the way to go then i will take you up on your offer of borrowing the bottom sprocket tool
reading the workshop manual, one of the 1st steps is to measure the cam clearances with e feller guage.the picture is a bit vaugue hence this post.
does it mean the distances between the back end of the cam lobe and the engine block which will tell you the amount of wear on the cam lobes?
or is it something else?
also the front two valves, is the 1st one the inlet and 2nd one the exhaust?
does it mean the distances between the back end of the cam lobe and the engine block which will tell you the amount of wear on the cam lobes?
or is it something else?
also the front two valves, is the 1st one the inlet and 2nd one the exhaust?
OK, maybe this is a dumb question, but I've never really understood the whole valve timing job...
Whats just been described about is the setting of the valve clearences, right? Sounds simple enough: use feeler gauges to measure th gap between the bucket and the cam. Presumably then you only need the retaining tool if you find that the clearances are out, as this obviously requires the cam to be removed to get at the shims?
So... whats all the stuff about setting the timing then? Surley if you're putting the cam back in the same position as you took it out (and its not a vernier cam or anything?), then the timing hasnt changed? So whats all the stuff about "equal lift on overlap". Surley the physical design of the cam fixes how much lift the ilets or exhausts have at any given engine angle?
Or perhaps I have it all wrong!?
Whats just been described about is the setting of the valve clearences, right? Sounds simple enough: use feeler gauges to measure th gap between the bucket and the cam. Presumably then you only need the retaining tool if you find that the clearances are out, as this obviously requires the cam to be removed to get at the shims?
So... whats all the stuff about setting the timing then? Surley if you're putting the cam back in the same position as you took it out (and its not a vernier cam or anything?), then the timing hasnt changed? So whats all the stuff about "equal lift on overlap". Surley the physical design of the cam fixes how much lift the ilets or exhausts have at any given engine angle?
Or perhaps I have it all wrong!?
To check the valve clearances you're right - you don't need to worry about upsetting the timing because everything is still all bolted together. However, having measured the actual gaps, if you need to make adjustments then it is necessary to remove the cams in order to put a greater or lesser thickness of shims in. Therefore you need to make sure that the crankshaft stays still - at Top Dead Centre - so that you can ensure that when you replace the cams you can time them properly in relation to the (known!) position of the crank.
The issue about equal overlap relates to the fact that, on "sportier" engines there is often overlap on the cams. This means that when the exhaust valve is opening, the inlet valve is still not closed. This means that unburnt fuel escapes down the exhaust ports and makes all the popping on the overrun! Equal overlap means that the ammount that the exhaust port is open by should be the same as the ammount that the inlet port is open by - albeit one is opening whilst the other is closing.
If you imagine a clock, you could say that the exhaust port should be at 10 minutes to the hour when the inlet is at 10 past - you don't want one to be at 5 to and the other 10 past.
having just re-read what I've written, I'm not sure how clear I've made it - but hopefully it helps!
The issue about equal overlap relates to the fact that, on "sportier" engines there is often overlap on the cams. This means that when the exhaust valve is opening, the inlet valve is still not closed. This means that unburnt fuel escapes down the exhaust ports and makes all the popping on the overrun! Equal overlap means that the ammount that the exhaust port is open by should be the same as the ammount that the inlet port is open by - albeit one is opening whilst the other is closing.
If you imagine a clock, you could say that the exhaust port should be at 10 minutes to the hour when the inlet is at 10 past - you don't want one to be at 5 to and the other 10 past.
having just re-read what I've written, I'm not sure how clear I've made it - but hopefully it helps!
yes rotate the crank so that each valve is fully closed, ie top of cam lobe 180 degrees away from the bucket face.
I`d do this before you remove the timing cover, otherwise the shaft for the timing chain sprocket starts to come out of the bearing housing in the crankcase, hence why I made the tool up.
so measure up all the valve clearances and write them down as you go, then if you do find any are to big a gap, remove the cam, remove the bucket and the shim then measure the shim with a micrometer, add the gap size to the shim size, them deduct the 10 or 12 thou, depending on wether its an inlet or exhaust valve you are working on, the figure left is the correct thickness of the new shim required.
make careful notes and keep a record of the shim thickness`s with their corresponding cylinders, you may find that one of the shims that is to be replaced will fit perfectly in another place.so in a worst case scenario instead of needing to but 16 shims you may only need 8 for example.
I`d do this before you remove the timing cover, otherwise the shaft for the timing chain sprocket starts to come out of the bearing housing in the crankcase, hence why I made the tool up.
so measure up all the valve clearances and write them down as you go, then if you do find any are to big a gap, remove the cam, remove the bucket and the shim then measure the shim with a micrometer, add the gap size to the shim size, them deduct the 10 or 12 thou, depending on wether its an inlet or exhaust valve you are working on, the figure left is the correct thickness of the new shim required.
make careful notes and keep a record of the shim thickness`s with their corresponding cylinders, you may find that one of the shims that is to be replaced will fit perfectly in another place.so in a worst case scenario instead of needing to but 16 shims you may only need 8 for example.
Edited by clive f on Friday 13th February 16:56
so if i measure the gap between the cam and bucket and for example say its 0.003 then remove all the gubbings and measure the shim and thats 0.007, add them together and thats 0.010, deduct that from say the exhaust value of 0.012 that leaves you 0.002 so does that mean i need a shim 0.002 of an inch bigger?
No - I don't think so (or maybe I haven't understood your description properly.
You need to create a gap of 12 thou, if you currently have a gap of 3 thou then you need to remove 9 thou of shims.
You may find that, if you have a particularly tight gap you will need to grind down an especially thin shim to suit.
You need to create a gap of 12 thou, if you currently have a gap of 3 thou then you need to remove 9 thou of shims.
You may find that, if you have a particularly tight gap you will need to grind down an especially thin shim to suit.
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