11 replies to this topic

[Bravo_Zulu]

Hey guys

I'm in the process of timing in my Kent 266, I have lined it up dot to dot then used a DTI to fine tune, the end result came 103 degrees ATDC, Kent list the max lift for the cam at 106 degrees... so is 103 close enough or will i need to use a off set woodruff to bring it in to 106?

[bmcecosse]

Dot to dot is fine - it's not a racing engine !

[jaydee]

I'd keep it as it is, cause 103° is better than 106° due to chain stretch/wear, espescially in a simplex chain setup.

[Bravo_Zulu]

Cheers guys, one can never be to careful with these matters.

[Ethel]

Mr Vizard has a good argument - since the siamese ports behave differently there's no precise sweet spot, what's worse for 2 cylinders will be better for the others (within reason), hence why there are scatter pattern cams.

[jaydee]

Mr Vizard has a good argument - since the siamese ports behave differently there's no precise sweet spot, what's worse for 2 cylinders will be better for the others (within reason), hence why there are scatter pattern cams.

Thats very true

[Cooperman]

With a new timing chain 103 degs will be just about ideal as the chain will stretch about 2 degrees after approximately 5000 miles, less if it's revved as a 286 needs to be, and then ity will be virtually perfect. The reason for checking and re-setting is now necessary due to the inaccuracies in after-market sprockets and cams. I've seen a dot-to-dot figure of 9 degrees retarded from nominal with all new cam and sprockets and that certainly would not be good enough, even for a road engine.

[bmcecosse]

I am assuming properly made original engine parts - not junk from China !!

[mini13]

yep, I too ave seen dot to dot cams a mile out...

th reason is a reground cam isnt nececasilay ground in the same place as the original profile was.

[Bravo_Zulu]

With a new timing chain 103 degs will be just about ideal as the chain will stretch about 2 degrees after approximately 5000 miles, less if it's revved as a 286 needs to be, and then ity will be virtually perfect. The reason for checking and re-setting is now necessary due to the inaccuracies in after-market sprockets and cams. I've seen a dot-to-dot figure of 9 degrees retarded from nominal with all new cam and sprockets and that certainly would not be good enough, even for a road engine.

Ahh great stuff, seems like i have been lucky then.

[Cooperman]

For the small amount of effort involved and the number of different components each with a manufacturing tolerance it's always worth while checking. Then, if dot-to-dot proves accurate you've lost nothing, but if the timing is more than 2 degress or so out it's easy to make it absolutley correct. It's called thoroughness.

[dklawson]

I am assuming properly made original engine parts - not junk from China !!

You know what they say about assuming.

As Cooperman said, it doesn't hurt to check the cam angle when it is set dot-to-dot. It will reveal if you need to make changes.