SBC Cam Questions
04-03-2006, 01:42 PM
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SBC Cam Questions
I知 considering upgrading the cam in my 383 stroker engine, and I知 stuck between two cams. The current cam is a Comp XM-262-H #12-236-3. This is a flat tappet cam. The ones I知 looking at are both hydraulic roller cams by Comp. XR-276HR-10 #12-423-8, and XM-276HR-12 #12-418-8. These cams seem to be virtually identical with the exception of lobe separation angle My questions are: How different would either cam make the engine run?
What advantage/disadvantage would I see with either cam?, And Which cam would be less prone to reversion? Currently the engine has stock style cast iron heads with port work, 9.5:1 compression, a cast iron high rise intake manifold, and stock style center rise exhaust manifolds. In his book, Dennis Moore recommends the XR-276HR-10 cam. Any comments would be most welcome.
Camshaft Specification Table
Part Number 12-423-8
Engine 1955-1998 Chevrolet262ci-400ci8cyl.
Grind Number CS XR276HR-10
Description
Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.502 0.51
Duration At 0.006 Tappet Lift 276 282
Valve Timing At 0.006
Open Close
Intake 32 64
Exhaust 75 27
These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.335 0.34
Lobe Separation 110
Recommended Valve Springs 986-16
----------------------------------------------------------
Part Number 12-418-8
Engine 1955-1998 Chevrolet262ci-400ci8cyl.
Grind Number CS XM 276HR-12
Description
Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.503 0.51
Duration At 0.006 Tappet Lift 276 282
Valve Timing At 0.006
Open Close
Intake 28 68
Exhaust 75 27
These Specs Are For The Cam Installed At 110 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.335 0.34
Lobe Separation 112
Recommended Valve Springs 986-16
What advantage/disadvantage would I see with either cam?, And Which cam would be less prone to reversion? Currently the engine has stock style cast iron heads with port work, 9.5:1 compression, a cast iron high rise intake manifold, and stock style center rise exhaust manifolds. In his book, Dennis Moore recommends the XR-276HR-10 cam. Any comments would be most welcome.
Camshaft Specification Table
Part Number 12-423-8
Engine 1955-1998 Chevrolet262ci-400ci8cyl.
Grind Number CS XR276HR-10
Description
Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.502 0.51
Duration At 0.006 Tappet Lift 276 282
Valve Timing At 0.006
Open Close
Intake 32 64
Exhaust 75 27
These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.335 0.34
Lobe Separation 110
Recommended Valve Springs 986-16
----------------------------------------------------------
Part Number 12-418-8
Engine 1955-1998 Chevrolet262ci-400ci8cyl.
Grind Number CS XM 276HR-12
Description
Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.503 0.51
Duration At 0.006 Tappet Lift 276 282
Valve Timing At 0.006
Open Close
Intake 28 68
Exhaust 75 27
These Specs Are For The Cam Installed At 110 Intake CL
Intake Exhaust
Duration At 0.05 224 230
Lobe Lift 0.335 0.34
Lobe Separation 112
Recommended Valve Springs 986-16
04-11-2006, 02:18 PM
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Location: Fairview, NC
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Re: SBC Cam Questions
I am running the XM270HR in my SBC 400. It has a nice lope to it and will idle at 750 rpm which is important with an Alpha 1 outdrive. I'm turning a 14 1/4 x 20 screw at 5400rpm which is good for 60 mph. This is in a 20 footer that weighs in over 4000lbs.
