Bolt-style cams - what's the trick to rotation when timing them?
 

I think the title says it all...

The past few engines I have assembled had the early nut style cams. Timing them was easy. setup the dial gauge, loosen the nut, pull the pin, use the cam socket to rotate the cam to the desired lift at overlap and then reassemble.

I am setting timing on the newer bolt-style cams. Now there is nothing to grab the cam with to rotate it to the desired spec.

Are there any tricks for fine rotation and adjustment? I can grab the sprocket with the late style cam tool but the cam tends to rotate with it. maybe a long bolt that will bottom on the cam fixing bolt hole would work. I suppose I can grab the lobes through one of the rocker mounting access holes in the cam tower but my hand have enough time fitting in there and oil coated cam lobes do not have much friction to spin with.

There has to be a simpler way. Thanks for the help.

I seat the bolt with a 3/8 impact then I can turn it either way and pin it. Its always worked for me.
Bruce

Say what?!

There is a tool for grabbing the cam by the pin holes. I suspect it's available on Pelican or you might be able to borrow one. It has a large hole in it so a socket can go on the bolt.

-Andy

The tool that Andy mentions is typically for counterholding the cam sprocket when the sprocket is pinned, in order to loosen the cam bolt. When the bolt is out and the cam sprocket is not pinned to the timing chain outer sprocket, what Jamie is saying is that the tool will indeed rotate the sprocket and sometimes (all the time in my limited experience) the cam will rotate with it. This is a problem because you want the cam and sprocket to remain independent so you can tweak the timing.

My solution was similar to what Bruce said- bottom a bolt in the cam snout that is tight enough to not loosen if you want to rotate the cam, via the bottomed bolt, counterclockwise. However I was a candy a$$ when I did my work and didn't want to bugger up the cam threads. So my bolt would not stay tight enough to prevent loosening when i'd counterhold the bolt. So I simply kept trying to get the cam to not move with the sprocket by jiggling the sprocket. Should have tried to block one of the lobes like Jamie mentioned.

I use a drift punch that is slightly smaller than the lock pin, and rock it in the hole, pressing the backside sprocket tooth in the direction that I need the cam to rotate. This allows a small movement when you're close to your overlap value. I just pick the hole that is closest to alignment that allows the lock pin in, and press it so the pin fits. Check the overlap and repeat as necessary.

If your worried about damaging the threads by bottoming out a bolt,. Couldn’t you put a nut on the bolt, screw it in an inch or so and lock the nut against the cam. You wouldn’t be loading the threads any more that when you use it to hold the washer that holds the sprocket on

Just a thought…

Jamie, try turning the engine with lock pin installed to desired setting, then remove the pin and turn the engine back to Z1, then reinstall the pin.
Warren

snug the bolt, not very tight and run the cam timing up to where you want it, take the bolt out, take the pin out, and turn the crank forward or backward to TDC. install the pin, snug the bolt and recheck to see if it's right on.

Thanks there are some good suggestions. I did have a problem with the cam turning back against the valve spring tension when I tried to pull the pin and rotate the sprocket.

Jamie