piston/valve clearances
 

I am in the later stages of a rebuild of my 3.0 SC engine. I am checking the piston to valve clearances. I had all new valves, seats reground, and heads resurfaced. Because of the resurfacing, I made sure the deck height was on the high side. On bank 1-3, my clearances are tight. Exhaust is about .75 mm and intake is just over 1 (~1.125) mm. Clearances on bank 4-6 are similar. I fear I have to rip everything back down and install thicker gaskets, or will I be okay with these clearances? I don't race my car (ever) if that makes a difference. Any help is greatly appreciated.
-Mike

I have also installed 964 cams, if that makes any difference with the clearance.
Thanks.

Way too close, this engine will self-destruction (likely) when it's warmed up.

You need 1.5mm on the intake and 2.0mm on the exhaust.

-Wayne

How did you measure it? Plastiguage? Valve adjust screw method?

Before you tear down, let's make sure the measurements are correct?

I used the adjustment screw method and followed the procedure in Wayne's rebuild book. I removed the tightening nut and tightened it to the point of resistance (contact with the valve). I then marked a spot on the rocker arm and the adjustment screw, to ensure I would come back to the same spot each time. I took frequent measurements and got a minimum clearance of 3/4 of a turn on exhaust and 1 1/8 of a turn on intake. I took these to be .750 mm and 1.125 mm, respectively. Did I do this correctly? I would REALLY like to avoid tearing this thing back down to add a thicker base gasket.
Thanks.

the left bank of cylinders had the tolerances listed above. The right bank had clearances of 1.25 for intake and 1.125 for exhaust. Will I be okay with these on this side so that I only have to tear down one half of the engine?

Mike,

See Wayne's post. You must have: "You need 1.5mm on the intake and 2.0mm on the exhaust." It is only prudent.

You can also machine groves into the pistons...

You didn't mention turning the crankshaft. Are you sure the rocker was fully on the back of the lobe when you set the screw?

I will double check to make sure they were on the low point of the camshaft. I set the clearance to zero at 0 deg, TDC (not at valve overlap).

Not trying to make you do more work, but hopefully it will be something easy rather than more machine work...

Well, I double checked them. I am still getting the same thing. I ripped the engine back down to the case. I am just going to install thicker copper base gaskets to get the clearances I need. I guess it was just unavoidable. Thank you for your help.

Good luck. Good thing you checked!