I was mocking up my engine and noticed that the top edge of the valves and the edge of the valve reliefs were close. The depth is more than adequate, but I was just wondering how much room between the valve relief edge and the valve is necessary.

 

You will get some debate among engine builders. But the most common recomendations for an aluminum head/steel rod combo are 0.080" clearance on the intake valves and 0.100" or 0.110" for the exhaust.

Rich Krause

 

I am using offset dowels to move the heads closer to the lifter valley to overcome using an extra thick gasket. This makes the valve closer to the edge of the relief, not the depth of the relief.

I have plenty of clearance "depth wise". What I am questioning is the closeness of the valve edge to the edge of the valve relief. If looking at the piston from the front of the engine, the valve edge is really close to the "cliff" edge of the valve relief, not the bottom of the relief.

I really dont see how the piston and valve could hit because they dont travel any in this direction, but I was wanting some input.

 

Define "close". IMO, if it's less than .050 nto the edge, I might be concerned.

Rich?

 

I would say that it is a little closer than .050. I was using the clay method so it is hard to get a totally acurate measurement. I am guessing around .030"
This was with the .030" offsets. I may just use the .015" offsets. Thanks