Help with this cam doctor report / specs
03-22-2005 | 09:40 PM
#1
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From: New Baltimore , M.I.
Help with this cam doctor report / specs
I got this report to find what the cam was. Well looks like rocket science, I belive I still have to figure out lift with my 1.5 ratio rockers. If you know how to read this, how is this cam for a hot sbc w/dry exhaust??
03-23-2005 | 02:38 AM
#2
Charter Member # 55
Joined: Oct 2000
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From: Omaha/LOTO
Re: Help with this cam doctor report / specs
They only measured 2 lobes. Intake #1 and exhaust #1.
Intake 1 is on top & exhaust is on the bottom.
Intake duration is 222.6, exhaust duration is 233.6. these would be the advertised durations at .050.
Not sure how they get their valve lift #'s??????
It look to me like intake lift would be .30929 x 1.5 = .464
and exhuast would be .32322 x 1.5 = .484
Don't quote me for 100% certainty though.
Intake 1 is on top & exhaust is on the bottom.
Intake duration is 222.6, exhaust duration is 233.6. these would be the advertised durations at .050.
Not sure how they get their valve lift #'s??????
It look to me like intake lift would be .30929 x 1.5 = .464
and exhuast would be .32322 x 1.5 = .484
Don't quote me for 100% certainty though.
03-23-2005 | 06:38 AM
#3
MarineKinetics
Joined: Oct 2002
Posts: 942
Likes: 4
From: Rochester, NY
Re: Help with this cam doctor report / specs
kmiller,
Rounding to the nearest, the cam card would read:
284*/290* @ .006”
223*/234* @ .050”
131*/141* @ .200”
112* LSA
108* ICL
IVO 28* BTDC
IVC 77* ABDC
EVO 79* BBDC
EVC 31* ATDC
59* Overlap
4* Advance
.309” I lift lobe/ .323” E lift lobe
.475”/ .485” valve, with 1.5 ratio which are inverted on the chart
Base circle run-out is well within tolerance
Peak opening and closing lifter acceleration is equal suggesting a symmetrical lobe.
Peak nose acceleration is the negative value as the lifter moves over the nose. This value is important for spring rate.
Lift at TDC is the amount both valves are open @ TDC, indicating the advance/retard position. Crossover is the point where the intake and exhaust valve are open equally, in this case about 4* BTDC
The lobe area is obtained by measuring the lift at each degree of rotation and adding them all together.
Bob
Rounding to the nearest, the cam card would read:
284*/290* @ .006”
223*/234* @ .050”
131*/141* @ .200”
112* LSA
108* ICL
IVO 28* BTDC
IVC 77* ABDC
EVO 79* BBDC
EVC 31* ATDC
59* Overlap
4* Advance
.309” I lift lobe/ .323” E lift lobe
.475”/ .485” valve, with 1.5 ratio which are inverted on the chart
Base circle run-out is well within tolerance
Peak opening and closing lifter acceleration is equal suggesting a symmetrical lobe.
Peak nose acceleration is the negative value as the lifter moves over the nose. This value is important for spring rate.
Lift at TDC is the amount both valves are open @ TDC, indicating the advance/retard position. Crossover is the point where the intake and exhaust valve are open equally, in this case about 4* BTDC
The lobe area is obtained by measuring the lift at each degree of rotation and adding them all together.
Bob
03-23-2005 | 07:18 AM
#4
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From: New Baltimore , M.I.
Re: Help with this cam doctor report / specs
Thanks Bob. I take it your an engine builder, I wish more people would be as help full as you. Alright now that bob made it clear how does that cam look for this engine.
I currently have 350sbc World Products Sportman II heads 72cc, crane roller rockers ( the gold 1.5 ratio ), .060 over flat top 4 valve notch pistons, performer rpm intake, Gill Manifolds Running as true dry exhaust (no fakes), not sure as of yet what my old cam size was ( getting checked ), I am not looking to spend the money for a full roller cam in this motor. This is in a 26' scarab cv @ 3,200lbs. I want to take full advantage of the dry pipes and still have an easy to start and idle boat????
I currently have 350sbc World Products Sportman II heads 72cc, crane roller rockers ( the gold 1.5 ratio ), .060 over flat top 4 valve notch pistons, performer rpm intake, Gill Manifolds Running as true dry exhaust (no fakes), not sure as of yet what my old cam size was ( getting checked ), I am not looking to spend the money for a full roller cam in this motor. This is in a 26' scarab cv @ 3,200lbs. I want to take full advantage of the dry pipes and still have an easy to start and idle boat????
