i know this has been answered a hundred times before, but my computer is gay and won't load the search page.


anyway....I'm trying to remember what the stock valve size is. Also I'm looking to have some porting done this winter and I want to upgrade the valve size. I remember reading something about 2.00 and 1.56 valves will fit in the stock valve seat, is this true, or do I need to have a new valve seat cut?

 

2.0 is the largest size to fit a stock seat and have a descent lap pattern.

 

I'm running 2.0 I and 1.56 E in a mildly ported set of LT1 heads with stock seats.

 

Stock seats? As in you don't have to cut a bigger hole for the valve? What is the point of getting a bigger valve if the hole is still the same? Or am I missing something?

 

If you install larger valves, they won't do you much good unless the ports are machined to accommodate them. JMHO

 

When the heads are ported the bowls are opened up for the 2.0 valves.

 

Yeah, but the bowl will not matter if the hole is still the same size. To me there is no point in getting a bigger valve if the hole the air is going through is going to be the same size. Bigger valve with same sized hole does not mean more air flow.

 

The bowl includes the ID of the valve seat.

 

oh... my bad

 

At issue is, the bigger the valve, the bigger the hole, and the closer the OD of the valve seat will be to the OD of the seat insert itself. The less material left, heat transfer becomes an issue along with durability of the pressed in seat.

 

The 2.0 valve works just fine in the stock castings and so does the bowl hogg(bowl porting)

 

The aftermarket valves are also designed to flow better as the shape of the valve leading to the valve stem has been improved for flow.