Pros/cons of sinking valves to clear bigger cam
04-26-2008, 06:29 AM
#1
Pros/cons of sinking valves to clear bigger cam Like it says. I wonder if the compression bump will more than offset the loss of flow? Do you also lose efficiency of burn from altering CC size from the factory design. I hear so much both ways
04-26-2008, 10:27 AM
#3
TECH Senior Member
He is saying sinking the valves for more PTV clearance.
Cons:
1-You are altering the geometry, so centering the geometry becomes necessary
2- Loosing flow
Pros: it clears a cam that normaly would not, but not by much. In order to satisfy the market many vendors ignore proper PTV safe limits. most will just say "yeah it clears" but the trick question is " By how much
"
Cons:
1-You are altering the geometry, so centering the geometry becomes necessary
2- Loosing flow
Pros: it clears a cam that normaly would not, but not by much. In order to satisfy the market many vendors ignore proper PTV safe limits. most will just say "yeah it clears" but the trick question is " By how much
"
04-26-2008, 12:14 PM
#4
He is saying sinking the valves for more PTV clearance.
Cons:
1-You are altering the geometry, so centering the geometry becomes necessary
2- Loosing flow
Pros: it clears a cam that normaly would not, but not by much. In order to satisfy the market many vendors ignore proper PTV safe limits. most will just say "yeah it clears" but the trick question is " By how much "
Cons:
1-You are altering the geometry, so centering the geometry becomes necessary
2- Loosing flow
Pros: it clears a cam that normaly would not, but not by much. In order to satisfy the market many vendors ignore proper PTV safe limits. most will just say "yeah it clears" but the trick question is " By how much
"Dont do it....it will kill your low and midlift flow unless you carefully blend the chamber out from the new established VJ height, then blend the bowls and short turn. Not something for the average cylinder head shop to tackle, never mind private individual (unless they have alot of hands on experience in that area).
Flycut and be done with it....no issues with geometry or flow and you get the room you need to safely run the larger cam.
I especially liked Mark's (Pred Z) last line about vendors ignoring how much P to V you actually should have....its been an issue with quite a few of them. "Clearing" and having enough room to save your bacon in an over-rev or missed shifts are two completely different numbers, although in an effort to make cam sales, the latter of those two figures often gets overlooked.
Tony
