Sanity Check: Exhaust Valve to Block Clearance OK

[240260280z]

I have 2.1mm clearance with head gasket in place but not torqued and hand pulling valve to seat (no spring). I assume ~ 1.6 to 1.8mm clearance when torqued. Is this enough clearance between the exhaust valve and the notched block?

Data:

Head = Maxima N47

Block = 240z P90

Cam lift = 7.7mm

Lift @ valve = 11.6mm (extrapolated @ 1.5X)

Mock up measured valve lift to collision (no spring & HG not torqued): 13.7mm

Just need to know so that I can wash the block and start rebuilding

Thanks!

[Walter Moore]

I looked and looked at your setup before I noticed that you have a Maxima head. Are you calculating this clearance, because I don't understand how you could measure this.

I assume that any clearance is better than none. As the valves and block heat up the valve and other parts may grow slightly taking up some of your clearance, but I would be hard pressed to believe that they would grow by enough to use up 1.6mm.

Isn't the intake valve bigger than the exhaust valve? How much clearance does it have?

[240260280z]

Thanks. I measured with calipers' depth gauge feature. I simply put the head on the block with gasket and 1 exhaust valve. I pulled the valve up by hand and measured the top of valve to top of guide depth. I then let the valve drop and hit the head where I notched and measured the same points. The difference is the max lift to crashing.

My concern is that the compression of the gasket will cut into the buffer space. I also used 1.5X as the lift multiplier from cam to valve (I measured both axis of valve lobe to get lift) but I saw several references that are less than 1.5X so that extra may help me a little if I over estimate. I am just not sure how much thermal expansion and valve over shoot will happen. I see 2mm as valve to piston clearance so I exceed that one.

You are right about valve size. The intake is bigger; but the exhaust is the problem. Its margin is outside of the cylinder.