6 replies to this topic

[Sam_Gpz600r]

Hi all, been rebuilding a road use 1293 with kent 266 cam (with fixed duplex timing gear) and got to checking the timing of the cam. Spec of the cam states 106 degrees but the dot to dot lines the cam up to 112 degrees. This is 6 dedrees retarded if I am correct?

 

So what i am really looking for is some advice on setting up the advance on the cam, what should i set it to?

 

-Some people set it just dot to dot and ignore it. (I'm not keen on this as 6 degrees retarded sounds way out!?)

-Others say advance the cam around 4 degrees, ( I could do this by moving the cam gear around one tooth on the chain and it should be 103 degrees therefor 3 degrees advance)

-And the rest say line it 1 degree advance to allow for chain stretch.( this means a 5 degree key )

 

So what is the consensus on cam timing, which do i go for?

 

 

 

[Cooperman]

The Kent 266 (wonderful cam by the way) is timed in at a nominal 106 degrees. If you are also fitting a new timing chain, set the timing to 104 degs ATDC which allows for the initial chain stretch.

You can either use a vernier sprocket or off-set woodruff key.

Make sure you do the measuring very accurately. Do it 3 times and take an average, both before correcting and afterwards as a final check.

[59 Speed]

I have the luxury of having an adjustable cam pulley on mine and I set my Kent 286 (that should be 106 degrees) to 104 degrees after top dead centre (after Coopermans recommendations).

You might need to check with Kent cams though as when I emailed them to check where to take the reading from - fully open on the inlet valve or inlet pushrod, they stated at the valve.

Also I presume you have a DTI, if you're not doing it already make sure you find the TDC of the piston by finding the average of the dwell of the crank (if that makes sense). I had to use some brake pipe through the spark plug hole as shown below:
 image.jpg   78.5K   12 downloads

Finding full lift on no.1 valve:
 image.jpg   55.25K   9 downloads

Edited by Smackfiend, 26 September 2014 - 09:59 PM.

[Sam_Gpz600r]

That's great thanks guys, looks like it's time for a new woodruff key. I am doing it with the head off and using a dti making sure I am getting an average either side of tdc and full lift. It's the chain that was on there but I think it's probably best to go for 1 degree advance as you said cooperman.

So that would be at 105 degrees meaning I need a 7 degree woodruff key to compensate for the dot to do 112 degree. Seems like a large key. Or of I advance the cam sprocket by 1 tooth (9 degrees) then get a 2 degree key to retard it back to 105. I know it seems like a bit of a complicated way around but I think I would prefer a smaller offset key.

[59 Speed]

I am certainly no cam timing expert and I'm just following others advice, but they have said the difference between timing it on the push rod and timing it at the valve cap could be upto 4 degrees difference.

I contacted Kent cams and they stated that my cam (286) should be set at full lift at the top of the valve.

[Sam_Gpz600r]

Ahhh ok, that's good to know. So it's best to time the cam in with the head on and using the vaves?

 

Im getting a bit confused now, I thought I had it all sorted :/

[Gremlin]

No best to do it on the push rod, less chance if error because theres no rockers in the equation that have tolerances, slightly advanced camshaft timing would result in more bottom end torque and less top end power, the 2 degrees advance that you would get if you moved it a tooth would be ideal