Firstfives.org

Thought this might be of interest with regards to valve clearance (non -hydraulic tappets) but slightly off topic

Tyrells Classic workshop has a video on the valve resetting of a Fiat/Ferrari Dino V6

This youtube link - go to the 7.30 - 9.00 min for valve clearance description.



If I may
what Ian describes is the requirement for valve clearance and why 0.30mm (0.012in) is the prescribed value - which from what I understand is that when the valve is off cam - the follower is not touching the cam shaft ( which causes wear if it does touch) and 0.30 (0.012in) is so that there is still a clearance once everything has heated up ( and expanded) .

proper clearance leads to better performance, less noise + a smoother running engine.

Gary, great find!

I'm wondering if it would perhaps, be more exacting, to set tappet clearance with the camshaft sideways, beginning its contact with the tappet surface.

What I mean is, when the gentleman explains the gradual eccentricity slope is intended to "gently" engage with, and then press down the tappet, if by placing the camshaft at exactly that position and THEN tightening the adjusting thread, would it be a more precise adjustment?

Of course, rotating the cam around and ensuring that clearance is present would be paramount.

But....then again, I'd suppose just measuring factory clearance at the bottom of the eccentricity would net the same results...

Oh well, just thinking out-loud.

Mike

keehn wrote: Wed Jul 08, 2020 5:54 am I'm wondering if it would perhaps, be more exacting, to set tappet clearance with the camshaft sideways, beginning its contact with the tappet surface.

What I mean is, when the gentleman explains the gradual eccentricity slope is intended to "gently" engage with, and then press down the tappet, if by placing the camshaft at exactly that position and THEN tightening the adjusting thread, would it be a more precise adjustment?

The cam grinder specs the clearance using the base circle of the cam, and the adjustment is always made on the heel of the cam. Trying to find the exact position of the cam where the ramp starts would be a very futile effort and would result in no change from the lash set on the mid-point of the heel. There is also a range of lash to take into account. You can alter the effective duration of the cam and it's performance by using the limits of the range. More lash equates to less effective duration and more low end power, while tightening the lash produces better top end.


He needs one of these:

onovakind67 wrote: Thu Jul 09, 2020 8:36 am

keehn wrote: Wed Jul 08, 2020 5:54 am I'm wondering if it would perhaps, be more exacting, to set tappet clearance with the camshaft sideways, beginning its contact with the tappet surface.

What I mean is, when the gentleman explains the gradual eccentricity slope is intended to "gently" engage with, and then press down the tappet, if by placing the camshaft at exactly that position and THEN tightening the adjusting thread, would it be a more precise adjustment?

The cam grinder specs the clearance using the base circle of the cam, and the adjustment is always made on the heel of the cam. Trying to find the exact position of the cam where the ramp starts would be a very futile effort and would result in no change from the lash set on the mid-point of the heel. There is also a range of lash to take into account. You can alter the effective duration of the cam and it's performance by using the limits of the range. More lash equates to less effective duration and more low end power, while tightening the lash produces better top end.


He needs one of these:

Agreed. Harbor Freight sells those stethoscopes for dirt-cheap. I have an old one in my toolbox as well.

Mike