head work questions...
Senior User
Joined: Feb 2004
Posts: 184
Likes: 0
From: Va Beach
I maybe wrong but I don't think valves are gonna effect your compression. The only thing that will effect compression is your piston style and having actual bowl work done. Valve work will however effect your flow rates.
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
About the only way it could change your compression ratio would be if you have to have larger valve reliefs cut into the pistons...and then, it would be minimal. Increasing the bore or stroke raises the compression, as does reducing the size of the combustion chamber. But increasing the valve sizes and flow capabilties won't change the compression ratio.
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
Now you're opening a new can of worms...! The largest practical size is for those heads is 1.94/1.60. I have a set with those valves and it gets pretty close between them. Some people have reportedly stuffed 2.02/1.60 valves into them but they practically touch...they might even have had to take a little material off the circumference of the valve head to get them to fit. There's also not much area between the valve at that point and the seats can overlap. Sounds to me like a good place to start to burn the valves or for a crack to start in the head. I don't think the risk is worth the gain. I'd go with 1.94/1.60s.
