For the 2nd time in a week I have broken my exhaust valve spring and bent the rod. Guessing my rod length is too long given my mods, but could use some input from the more experienced builders before I keep throwing money at the wrong solution.
Here is the motor setup in my Baja Warrior:
- Predator 212cc Hemi
- .356 lift cam
- .010 thin head gasket (no other head milling has been done)
- Stainless steel valves
- valve lash at 0.003
- chromoly push rods (stock length 5.54" long at .187" diameter)
- 26# springs with billet retainers
- stock rockers
- polished & ported head
- billet piston rod, gov removed, billet flywheel @ 32 degrees (I still need to install the 4 degree offset)
- Genuine Mikuni carb + header pipe
- peak RPM on last run was 6,100, highest RPM achieved under load is 6,440 RPM
Both times the valve spring broke while I was well under 6K RPM however. In fact yesterday I was just riding a woods trail with a few other guys when it happened.
Also, I know I should have 36# springs but the ones shipped to me are bigger diameter and so they don't seat properly in the head. I would have to ground out the head a bit and I don't have the tooling to do that. 26# springs are the biggest ones I can find that fit. At 6K RPM I figure I'm no where near valve float issues anyway.
EDIT: And FWIW, I have a friend that has built nearly the same motor but is running the .308 CAM, and yesterday he also broke the 26# valve spring on the exhaust port.
Here is the motor setup in my Baja Warrior:
- Predator 212cc Hemi
- .356 lift cam
- .010 thin head gasket (no other head milling has been done)
- Stainless steel valves
- valve lash at 0.003
- chromoly push rods (stock length 5.54" long at .187" diameter)
- 26# springs with billet retainers
- stock rockers
- polished & ported head
- billet piston rod, gov removed, billet flywheel @ 32 degrees (I still need to install the 4 degree offset)
- Genuine Mikuni carb + header pipe
- peak RPM on last run was 6,100, highest RPM achieved under load is 6,440 RPM
Both times the valve spring broke while I was well under 6K RPM however. In fact yesterday I was just riding a woods trail with a few other guys when it happened.
Also, I know I should have 36# springs but the ones shipped to me are bigger diameter and so they don't seat properly in the head. I would have to ground out the head a bit and I don't have the tooling to do that. 26# springs are the biggest ones I can find that fit. At 6K RPM I figure I'm no where near valve float issues anyway.
EDIT: And FWIW, I have a friend that has built nearly the same motor but is running the .308 CAM, and yesterday he also broke the 26# valve spring on the exhaust port.