Cam:Piston to Valve Clearance and compression with cam choice
03-23-2019, 08:47 PM
#1
Cam:Piston to Valve Clearance and compression with cam choice
I will forgo all the things going into my cam choice, I know everyone gets sick of that, but will say that I have just about decided on my cam but need a little more info JIC.
Would a 226/240 632/632 116 +4 cam have any Valve to Piston Clearance or Compression issues when used with unported LS7 heads that have been milled 0.010 to raise compression a bit?
I've seen people running MUCH higher lift but just need a some reassurance. I also do not have the engine dynamics knowledge to know if this cam choice with milled heads would cause way too high a DCR.
TIA,
RB
Would a 226/240 632/632 116 +4 cam have any Valve to Piston Clearance or Compression issues when used with unported LS7 heads that have been milled 0.010 to raise compression a bit?
I've seen people running MUCH higher lift but just need a some reassurance. I also do not have the engine dynamics knowledge to know if this cam choice with milled heads would cause way too high a DCR.
TIA,
RB
Last edited by ronsws6; 03-23-2019 at 10:47 PM.
03-24-2019, 02:56 AM
#3
Team Owner
The right springs and lightweight valves, you should have zero PTV issues with only a .010 mill and .632 lift. Heavy solid stem exhaust valve and the wrong springs, and/or aftermarket rockers...anything is possible. Plenty running much more lift, with .030 or .040 mill without issue though.
Last edited by MTPZ06; 03-24-2019 at 02:58 AM. Reason: Spelling
03-24-2019, 08:01 AM
#5
Plenty of room there.
03-24-2019, 09:59 AM
#6
Team Owner
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St. Jude Donor '05
Do you have a copy of the cam card you can post? Those #s dont say everything
03-24-2019, 10:54 AM
#7
Unfortunately no. I haven't ordered it yet. Pat G spec'd me a a similar cam at 216/236 with the same lift, but I decided to add a little more exhaust duration and mill the heads after getting the selection and I didn't want to have to bother him again. I will consult with cam motion before I order but just wanted a little reassurance from others as well. You know "Measure Twice, Cut Once" kind of thing.
Last edited by ronsws6; 03-24-2019 at 10:55 AM.
03-24-2019, 10:59 AM
#8
The right springs and lightweight valves, you should have zero PTV issues with only a .010 mill and .632 lift. Heavy solid stem exhaust valve and the wrong springs, and/or aftermarket rockers...anything is possible. Plenty running much more lift, with .030 or .040 mill without issue though.
03-24-2019, 02:48 PM
#10
I will forgo all the things going into my cam choice, I know everyone gets sick of that, but will say that I have just about decided on my cam but need a little more info JIC.
Would a 226/240 632/632 116 +4 cam have any Valve to Piston Clearance or Compression issues when used with unported LS7 heads that have been milled 0.010 to raise compression a bit?
I've seen people running MUCH higher lift but just need a some reassurance. I also do not have the engine dynamics knowledge to know if this cam choice with milled heads would cause way too high a DCR.
TIA,
RB
Would a 226/240 632/632 116 +4 cam have any Valve to Piston Clearance or Compression issues when used with unported LS7 heads that have been milled 0.010 to raise compression a bit?
I've seen people running MUCH higher lift but just need a some reassurance. I also do not have the engine dynamics knowledge to know if this cam choice with milled heads would cause way too high a DCR.
TIA,
RB
03-24-2019, 03:41 PM
#11
Which is one of the reasons I'm asking. I don't know if by adding 4 more degrees to the exhaust duration, if it will cause a problem. 632 lift with the 226/236 116+4 was fine before but by adding 4 degrees more exhaust duration I'd like to know if that lift will cause a problem.
03-25-2019, 12:38 PM
#14
Burning Brakes
PTV issues normally don't come into play until ATDC when the Intake valve is opening and chasing the piston back down into the hole.
OP, more than likely, you will not have any ptv clearance issues.
03-25-2019, 01:04 PM
#15
While true, you do not want the valve to be fully open at that point, TDC is not where the valve is going to be closest to the piston to interfere... So why bring it up?
PTV issues normally don't come into play until ATDC when the Intake valve is opening and chasing the piston back down into the hole.
OP, more than likely, you will not have any ptv clearance issues.
PTV issues normally don't come into play until ATDC when the Intake valve is opening and chasing the piston back down into the hole.
OP, more than likely, you will not have any ptv clearance issues.
Your argumentative response is a great reminder for me, to why I don't contribute on this forum anymore. Thanks!
03-25-2019, 04:07 PM
#16
Thats unfortunate....you have lots of good info to put out, I usually learn something new when you jump into threads!
03-25-2019, 08:46 PM
#17
Racer
Intake duration is a much more important factor than lift when it comes to piston to valve contact. And that 226* intake is not an issue AT ALL.
My 229*/242* duration, .661"/.661" lift cam with .040" head gaskets worked with my LS3 heads with no issues.
I'm certain the cam you're looking at with slightly milled LS7 heads is good to go!
Best of luck with your project!!
KW
My 229*/242* duration, .661"/.661" lift cam with .040" head gaskets worked with my LS3 heads with no issues.
I'm certain the cam you're looking at with slightly milled LS7 heads is good to go!
Best of luck with your project!!
KW
Last edited by KW Baraka; 03-25-2019 at 08:49 PM.
03-25-2019, 10:31 PM
#18
Melting Slicks
Zero issues!
I ran close to an 0.800" lift cam (258°/273° w112° LSA) with milled OEM LS7 heads and still had 0.100"+ clearance with stock pistons and 0.040" head gaskets!
I ran close to an 0.800" lift cam (258°/273° w112° LSA) with milled OEM LS7 heads and still had 0.100"+ clearance with stock pistons and 0.040" head gaskets!