Piston to valve clearance

[SinCity G8]

Does anyone know what the clearance is on the L76. TIA

Rob

[Crazy Paul]

No I don't know for certain on a stock L76.
A semi-educated guess would be
Intake something more than 0.190"
Exhaust something more than 0.210"

[Patrick G]

According to Richard with West Coast Cylinder Heads, the free valve drop on an L92/L76 head is:
.133" intake clearance
.160" exhaust

Add a stock .054" gasket thickness for your total clearance minus .006" amount that the piston is out of the hole.

[SinCity G8]

Thank you guys for the info. I am guessing haveing .010 to .020 taken off the heads will be ok then.

[Crazy Paul]

Thank you guys for the info. I am guessing haveing .010 to .020 taken off the heads will be ok then.

Yes.
0.180+ clearance now on the intake valve.
A lot of builders say 0.080 is the closest you want to go.
So you have 0.100" of meat to play with.

0.026 to 0.030 off the heads with stock gaskets normally gives you a static comp bump from 10.4 to 10.9

[MGM GT]

Yes.
0.180+ clearance now on the intake valve.
A lot of builders say 0.080 is the closest you want to go.
So you have 0.100" of meat to play with.

0.026 to 0.030 off the heads with stock gaskets normally gives you a static comp bump from 10.4 to 10.9

Indeed, taking off .030 is perfectly fine.

[Patrick G]

Thank you guys for the info. I am guessing haveing .010 to .020 taken off the heads will be ok then.

That's OK if you're running the stock cam. But for guys with bigger cams, there's really no room for milling without making P to V clearance too tight.

For example, a 230/234 .600/.602 114LSA +2 advance cam has .079" of clearance on the intake side. If this cam was advanced to +4, the P to V would then be .067". For what it's worth, you lose around .006" of P to V for every additional degree of duration. With the large intake valves, this limits us to how big we can go or how early we open the intake valve. Be careful milling with larger than stock cams.

[MGM GT]

That's OK if you're running the stock cam. But for guys with bigger cams, there's really no room for milling without making P to V clearance too tight.

For example, a 230/234 .600/.602 114LSA +2 advance cam has .079" of clearance on the intake side. If this cam was advanced to +4, the P to V would then be .067". For what it's worth, you lose around .006" of P to V for every additional degree of duration. With the large intake valves, this limits us to how big we can go or how early we open the intake valve. Be careful milling with larger than stock cams.

That said... I have my heads milled .030 and running a 236/242 .618 114 and it works fine. Honestly I want to go bigger... haha

[Patrick G]

That said... I have my heads milled .030 and running a 236/242 .618 114 and it works fine. Honestly I want to go bigger... hahaIf your pistons are not fly cut, then you're running around .052" clearance at 114 intake centerline, .040" at 112 intake centerline and .028" P to V at 110 ICL. Just thought you should know how tight you're running it. Don't over-rev that motor. You might wind up with little smilies on top of your pistons. :(

[MGM GT]

If your pistons are not fly cut, then you're running around .052" clearance at 114 intake centerline, .040" at 112 intake centerline and .028" P to V at 110 ICL. Just thought you should know how tight you're running it. Don't over-rev that motor. You might wind up with little smilies on top of your pistons. :(

No flycutting, redline is 72-7300... a few others have about the same setup, no problems to date with about 100,000 miles combined.

[Patrick G]

No flycutting, redline is 72-7300... a few others have about the same setup, no problems to date with about 100,000 miles combined.Just because you've had no problems does not mean that your P to V is wider than stated. Consider yourself (and the others) lucky. You can run P to V tighter than the textbook .080", but it leaves very little margin for error.

[MGM GT]

Just because you've had no problems does not mean that your P to V is wider than stated. Consider yourself (and the others) lucky. You can run P to V tighter than the textbook .080", but it leaves very little margin for error.

True true... its the stock engine though, if it fails it gives me a reason to go with that blown 408!

[Patrick G]

True true... its the stock engine though, if it fails it gives me a reason to go with that blown 408!Now you're talking!! :)