Valve spring/pushrod concerns
12-12-2011, 12:51 PM
#1
Valve spring/pushrod concerns Ok, now my forged 383 is put together I have two concerns about potential "weak links" in the valvetrain and want some opinions on this before the motor is run. Some background on the motor, it is a all forged 383, 11.3:1 comp, Lunati voodoo 60122, comp cams pro magnum 1.6 RR, LS7 lifters, stock pushrods, combination motorsports stage 2 cnc ported heads
1. Are stock pushrods holding me back? Do I need to upgrade to chromoly hardened pushrods? When do stock ones become marginal? (will spin it to 6700-6800 RPM)
2. The part number to the valve springs is unknown...they are Comp Cams springs, but Combination motorsports has been out of business for years, so can't cross reference with them (seller didn't know). I assume most aftermarket Comp cams springs should be able to handle up to .600 valve lift right? With the 1.6 rockers this cam puts me at .570/.586 lift....should I trust early 2000's comp cams springs with that much lift or just upgrade to lunati recommended spring kit 74818K5LUN (or the lunati pacaloy beehives 74818LUN)?
1. Are stock pushrods holding me back? Do I need to upgrade to chromoly hardened pushrods? When do stock ones become marginal? (will spin it to 6700-6800 RPM)
2. The part number to the valve springs is unknown...they are Comp Cams springs, but Combination motorsports has been out of business for years, so can't cross reference with them (seller didn't know). I assume most aftermarket Comp cams springs should be able to handle up to .600 valve lift right? With the 1.6 rockers this cam puts me at .570/.586 lift....should I trust early 2000's comp cams springs with that much lift or just upgrade to lunati recommended spring kit 74818K5LUN (or the lunati pacaloy beehives 74818LUN)?
12-12-2011, 01:23 PM
#2
i would definately get new pushrods. The springs is a tough call since we dont know pretty much anything about em other than brand name. I would go ahead and switch em out too once you get a chance. That way you know exactly whats on your build, and you avoid potential problems in the future
just my .02
just my .02
12-12-2011, 10:26 PM
#3
I would get .080 thick wall chrome moly PR. Trick Flo is one choice
check PR length and order size. On a engine rebuildmMachined/decked block & heads, head gasket thickness, cam lift, RR all effect PR length. 7.200" is stock but often a shorter one is needed
If heads are used and "x?" miles on springs might want to pull them and check spring pressure and see if it meets specs on cam card
check PR length and order size. On a engine rebuildmMachined/decked block & heads, head gasket thickness, cam lift, RR all effect PR length. 7.200" is stock but often a shorter one is needed
If heads are used and "x?" miles on springs might want to pull them and check spring pressure and see if it meets specs on cam card
