Tuning 'Abarth' camshaft

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Tuning 'Abarth' camshaft

I’ve got to install a 35/75 cam as well in the near future, so I’d appreciate input on this as well. I’ve only ever R&R’d a cam before - never done the degreeing of one.
 
Ey up guys,

I've got an 'abarth' spec 35/75 camshaft for my 650 engine, when installing it, all the timing Mark's lined up perfectly, but would I need to get myself a degree wheel and accurately time it with that?

Al.

Hi Al, It is accepted that the initial timing is ok if all your timing marks line up with a nice tight chain, but for exact timing a run on a rolling road and a tweak of advance will give results. To use a degree wheel for total exact timing you would need to elongate the holes in the camshaft sprocket (aka vernier) so that the cam can be set with a dial gauge to measure camshaft and valve lift. I would council that you find bolts above the standard rating to hold everything tight. The attached pic shows a vernier gear set using special bolts to hold the camshaft sprocket tight. The gears were all timed using a degree wheel and dial gauge.
Ian.
 

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As Ian mentions, to get the ultimate from your engine, your cam-timing should be set up with a 'degree-wheel'---there are a number of 'U-tube' films showing how to do this. However, for most "road-only use", a new timing chain and sprockets set fitted to the 'factory marks' will be perfectly sufficient. Yes, on a dyno you will see a difference in the power output, but on the road the difference might be difficult to discern. I would suggest that unless you are an experienced engine builder, for a "first time that I have buit one of these engines" effort (and for some people it will be THE first engine that they have ever built), keep it simple and go by the 'factory' marks--a 'dot' ON the tooth of one sprocket and a dot BETWEEN the teeth on the other. The cam sprocket will only fit in one position on the camshaft and the woodruf-key on the crank sprocket ensures that is in the correct position.
Fit the crank sprocket on first, then find where the cam-sprocket will align with the cam-shaft, then put the chain over the crank sprocket and then onto the cam-sprocket and then place the cam-sprocket onto the cam-shaft. It might not look like it will, but I assure you, the cam-sprocket holes will only align with the threaded holes on the camshaft drive flange in one position. Don't forget to use a new pair of tab-washers to lock the cam-sprocket screw-heads.
 
Install a 35/75 cam as well . Did any one get the checking clearance with their camshaft ? Mine didn't come with the cam card I am accustomed to.
 
The information that I have regarding a 35/75/75/35 camis:--inlets 8thou and exhaust 10thou COLD
 
What it is telling you is that the tappet clearance for both the inlet (aspirazione) and the exhaust (scario) is 0.25mm(10thou---or 9.8thou to be perdantic). The'h7.2' is the maximum lift of the cam lobe and the '290' is the number of degrees that the valve is open--290 for both the inlet and exhaust (35+ 75 +180) Ihonestlydon'tknow what the '010' is denoting.
It would seem that the valve clearances are slightly different on your 35/75/75/35 cam to mine.
 
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