Cam Shafts and stuff to do with them (from old site)
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contributed by Ian Simpson
My collected data pertaining to the 5GTT and some instructions and a 360° protractor to download.
Comparison
My data sheet comparing the details of various camshafts.
Note, when you click on the above link your browser will ask you whether you want to open this form. This is normal, it does not mean the form is laden with viruses or spyware or macros to take over your PC. Just that it is the type of file that could be. If you are worried then save the doc and scan it with all your protection software, transfer it to a floppy disc and open it on someone's computer you don't like very much. https://www.rtoc.org/boards/i/smile.gif
See this thread:
The Protractor
To download it, click on the image and it will enlarge. Then right click and click on 'save picture as' and select the folder on your computer to save it to then click 'OK'. It's 1.7Mbytes so will take about 5 minutes on a 56kbit modem or about 12sec on 1Mbit Broadband. You can then print it.
See this thread:
See this thread:
Some instructions to time the cam by Scoff:
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Essentially you TDC the engine, but be sure to use the TDC that has the distributor pointing to No.1 spark plug lead (since the engine will also be at TDC when it's pointing to No.4 spark plug lead).
Bolt the timing disc onto the crank pulley and install a pointer (made from a bit of wire clamped behind a bolt head or something). You now have a pointer pointing at "0" on the timing disc and the distributor arm is pointing toward HT lead No.1.
Rocker cover off, use a DTI (dial test indicator, or some other device capable of denoting rocker lift) you need to rest the DTI on the inlet valve of pot No.4. Zero the DTI.
You need to turn the engine over slowly by hand, in the correct direction of running, IE clockwise when viewed from the water pump/crank pulley end.
Peak lift for a BP285 piper should be at 112deg (some older ones were 110deg). Make a note of the angle on the timing disc once the DTI stops rising. Keep turning the engine slowly. Make another note of the angle once the DTI reading starts to fall again. The real peak lift angle will be half way between the 2 notes you've just made.
Repeat the test a few times, it's hard to get an accurate reading, take an average of all your results.
Note: Do not take an angle measurement if you turn the engine backwards! Slack in the timing chain will cause erroneous readings, if you turn the engine backwards for any reason, be sure to turn it forward slightly to remove any slack from the timing chain.
If the reading vary's from 112deg by more than a couple or 3 degrees then it's worth while correcting it with the vernier.
It's also worth noting that base cam timing isn't always the best setting for all applications! If you want a poky responsive engine at low rpm then try a upto 4deg of advance. The oposite applies too, if you want to make torque at high rpms (sometimes boosting peak HP) then you might like to try upto 4deg of retard. The trade off is that it will always feel flatter at the other end of the RPM scale.
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The Vernier pulley
If you have a Vernier pulley fitted one way to 'dial' in your camshaft is to use the rule of setting it so that at the same moment the exhaust valve is open by two thirds of the amount that the inlet valve is open. This might be likely to correspond to the manufacturers listed setting point, eg 112° ATDC.
Knocking inside your timing cover? Could be due to the Vernier being thicker than the original cog. You need either a thinner washer, a thicker (cork) gasket, to file down the bolt head or bash a clearance dent in the timing cover. See this thread
It's also been reported that the chain tensioner can jam or lock back and not tension properly. This also might make a noise.
Followers
They cost about £23 each from Renault. Come in two diameters, something like 19mm and 19.2mm, or so. Tend to wear concave which wears the lobes of the cam. In manufacturing they are ground Convex with something like a 72 inch or 144 inch radius. They can then be surface hardened and / or Parkerised. It's recommended by many people and companies, ie, Kent Cams, that new followers be used with a new or reground camshaft or the old followers could ruin the new lobes in only 20 minutes. Some people to save money do re-use old followers or even grind the surface hardened convex tip away so it's flat, but that's up to them.
See This thread.
Changing the cam by Sparkie's RTOC Profile https://www.rtoc.org/boards/images/bu...iend-small.gif
Many people have done this themselves, but I'm not sure many people have done it like this....
cam change with head on? many people talk about it, not many people do it.
basic instructions are...
1) bumper and bonnet off.
2) carb off (or carb top, depends if you have a strut brace or not).
3) distributor off and drive gear out.
4) rocker cover off.
5) undo tappets and take pushrods out.
6) take off alternator belt, crank pulley and crank pulley carrier.
7) undo exhaust 'Y' clamp from back of block.
8) undo front engine mount to subframe bolt.
9) unclip radiator so it sits slightly forward.
10) with a single magnetic 'pick up' pen lift each cam follower out of the block so that it rests at an angle on the top of the 'hole'- it should rattle around alittle- there is space under the head for you to do this!!
11) once all followers are 'loose', then jack engine up from sump plug till the engine mount thread clears the subframe.
12) if you have got a perc fan remove it!!! the hole into the inner wing is where you will feed the cam into!
13) once you have a little daylight on the timing cover, remove it, then the tensioner- make sure you don't loose the metal plate at the back of it - it likes to slip into the sump!!! turn the timing marks to face each other.
14) undo the cam bolt, and the two smaller locating bolts.
15) check to see that the followers ain't dropped back - I bet they won't have!
16) start to slide the cam out, and jack the engine up slightly until you can feed it the through the antiperc fan hole.
17) replace cam with new one.
18) put it all back together again!!
Ian S RTOC Profile https://www.rtoc.org/boards/images/bu...iend-small.gif
</td><td width="15"></td><td width="200">https://www.rtoc.org/articles/i/autof...14_148x150.jpg
360° Protractor
https://www.rtoc.org/articles/i/autof...14_150x112.jpg
A Piper camshaft
https://www.rtoc.org/articles/i/autof...14_112x150.jpg
360° protractor in use on Bill J's engine
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