Verify Valve Timing

Valve timing and lash measurements need access to the cam lobes. You will need to remove cam covers.

Of the two checks, I would rate valve clearance more important.

 

...because the timing is probably o.k. if the car runs. Worst case would be down on power.

You can verify general timing by putting 1-4 at TDC mark and verify the cam caps marks on the 4 camshafts. You will be within a few degrees of perfect doing this. Therefore you will only need to take the cam covers off. However, if you need to change a valve shim your options are using the valve depressor tool thingy (or make one) that I personally hate or just take the cams out which is more invasive but IMO faster and more accurate; since personally I would use a degree wheel to time and pull shafts to change shims. Basically...that is invasive.

 

You can pressurise the number one cylinder with low pressure (20 psi should be sufficient) at TDC on compression. Using a degree wheel you can verify opening points of the exhaust valve or the closing point of the intake valve on a degree wheel by carefully rolling the engine forward or backward and noting the point where air loss is indicated. Its a bit crude, but should be adequate for checking that the cams havnt jumped considerably. Repeat for number 5 to check the other bank. You cant check the other open/close points because both valves are in overlap and open at the same time.

 

Doh!!!! 2NA is correct. There is no physical way to check clearance without physically measuring it. And there is no real way to get your cams to exact valve timing, or to an altered valve timing, without a degree wheel and dial indicator.

 

Yes, to answer your exact question, but those non-invasive ways aren't the right way and would cost you more time/effort/money as well as be more error prone. I suspect *everyone* would frown on them.

But yeah, if you just *had* to check the valve timing and clearance non-invasively you could use a borescope through the spark plug hole in one cylinder combined with some sort of TDC device in that spark plug hole with the car jacked up and in 5th gear while someone hand-turned a rear-wheel forward.

Eek!

 

How long does it usually take for a Ferrari mechanic to check the valve clearance on a 308 GTB 2v V8 engine? Thanks.