Adjustable Cam Wheels - How to set-up?

[Datman]

Hi guys,

I am currently re-building my FJ20T which has after market Cams and modified cam wheels to allow for cam timing adjustment. Problem is I have never done this before, and need to learn how to set it up correctly.

Can anyone point me to a site on-line which has a good explanation of how to set up the cam timing? I know I will need a dial indicator and degree wheel, but how exactly do I use these?

Basically, My cam wheels have had the original locating holes drilled out, and an eccentric bush machined up for the holes, by moving the position of the bush, it adjusts the cam timing....... I should have taken some bloody photo's! I was just too keen to get it apart to determine the cause of our other problem - lack of compression!

Any help is appreciated.

Mark

[Datman]

Amazing what you can find if you look long enough!!!!!

http://www.automotivearticles.com/pr...amshafts.shtml - this article has the best explanation I have found on setting Cam timing.

From reading the above article, I now need to know.....

1. Where can I get a tool to put in the spark plug hole to stop the piston, and find the true TDC?

2. Where can I buy a degree wheel?

3. How can I find out the specs of my Camshafts? Is there someone I can take them too and have them "analysed" to get the specs? (In Sydney)

Thanks guys.

[hotgemini]

1. You can just jam a dial guage down the spark plug hole to find TDC, if necessary you might need to extend the gauge, our mechanics use TIG wire threaded into the guage.

2. Most cam places, or someone like a performance wholesale distributor.

3. Anyone running the camdoctor system, which measures your current specs.

[Datman]

thanks hotgem.... The TDC centre trick sounds good....will do that for sure.

Do you know of anyone in Sydney who uses the camdoctor system?

[hotgemini]

no idea, I still deny sydney exists.

[Datman]

Don't blame you there!

Found someone though...call enough places, and someone can usually help.

Camtech in Chipping Norton...$55 per Camshaft.

[proengines]

Datman,
the best way to find TDC is to use a dead stop rather than a dial gauge. The piston will sit stationary for a certain amount of time as it make the transition from going up to going down, its not an instant change so just reading when the piston is at its highest point wont give you true TDC, though it will be somewhere between when the pistons stops going up and starts going down.

A dead stop can be made from an old spark plug with the electrode broken out and a piece of steel bar welded in. It needs to be long enough to touch the piston before it gets to the top of its travel (say 5mm down). Make sure you round off the end so it doesnt damage the piston.

Screw the stop into #1 spark plug hole. Fit your degree wheel and a pointer and wind the engine in one direction until it stops turning as the piston contacts the dead stop, mark the degree wheel at this point. Turn the engine in the opposite direction until the piston comes in contact with the stop again, mark the degree wheel at this point. Half way between the 2 marks you have made is true TDC. Remove the stop, wind the engine to this point and then adjust the pointer so that it points at zero. This is the most accurate way to find TDC in my opinion.

Buy the biggest diameter degree wheel you can fit into where you are using it. The bigger the diameter, the further between each degree mark and the easier it is to see accurately. Most of the big cam makers sell them, if you are desperate, pick up a really big protractor from a drawing supply shop, it will do the same job. (Doesn't look as racy though).

The cam grinder should also be able to give you a spec for lift @ TDC. All you need to do once you have found true TDC is set up a dial gauge to measure cam lift, wind the engine over to TDC and read off the lift. If the spec you were given was, say, .080" inlet lift @ TDC and it reads .075" you need to advance the cam, if it reads .085" you need to retard it.

I don't know if I just made that sound really complicated but it's not, once you start to do it, it should make sense.

One other thing, on the FJ20 when you're measuring the lift, make sure the dial gauge is spot on at 90 degrees to the bucket follower or it will read a different lift to what the cam is actually moving it.

[Datman]

Proengines..... thanks heaps for the advice. I am planning on buying a degree wheel, as I am sure it wont be the last time the engine has to come apart.

I had read about the engine stop also, and I like the method you suggest for making one...sounds a lot cheaper

I am currently working on getting the Cam Specs, I discovered Wade Cams made them, so I have emailed them with the numbers which are stamped on the camshafts to get the specs...... hopefully that will save me taking them to the camdoctor.

Thanks again for the advice, I am pretty sure I can do this my self now.


Mark