Hello Experts,
I hope this is the right place to ask this question. I've got a stock zz4 350 with the Accel DFI Gen VII. Being stock, it has a "carb" camshaft. What is the difference between this and an "EFI" camshaft? Why is one better for EFI? Would I see appreciable perrformance or efficiency gain?
Thanks in Advance!
your carb cam timing is slightly different than the similar engine with the ideal EFI cam, but it won,t be a huge change as the cams LSA (LOBE SEPARATION ANGLE, DURATION and LIFT would be changed on an efi engine mostly to make the sensors for the efi read their data more clearly
keep in mind the cam was selected mostly for durability and reasonable power not to maximize performance.
heres your zz4 specs
10185071 Hydraulic Roller Tappet (ZZ4 Camshaft)
This hydraulic roller tappet is used on the 5.7-liter H.O. 350 ZZ3 & 4 engines. The duration at lash point in degrees (intake/exhaust) is 275/280; duration at .050†tappet lift (intake/exhaust) is 208/221; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 474/501. Valve lash is zero/zero and lobe centerline is 112 degrees.
http://www.gmperformanceparts.com/E...=ZZ4350&engine=ZZ4+350&sku=12499712&engCat=sb
G.M. says youll get 40 more hp swapping to the HOT CAM
12480002 Hot Cam Kit (LT4)
This off-highway camshaft kit has the major valve train component to convert production LT1 engine for showroom stock racing, or hop up your small block Chevrolet V8 that was originally equipped with a roller tappet camshaft. The 1.6 roller rockers, light weight valve spring caps, special designed valve springs and hot camshaft offers a significant gain in horsepower at a reasonable price. This kit includes the following items: one camshaft P/N 24502586, 16 roller rocker arms kit P/N 12370839, 16 valve springs P/N 12551483, 16 valve caps P/N 10212808, 16 valve keys P/N 24503856, 16 valve spring shims P/N 10212809.
Technical Notes: This kit does not include roller tappets. If your engine already has roller lifters, you can use them with this kit, but always check for wear and replace if needed before installing this kit. If you are building an engine from a bare block, you can use the roller lifter kit P/N 12371042.
Special Note For ZZ4 Owners: This kit is worth 40HP more when installed in a ZZ4 which will boost the horsepower from 355 to 395, but the ZZ4 comes with the most of the LT4 HOT Cam Kit components already installed. The camshaft and lifters are all that are needed to complete the LT4 Hot Cam conversion on the ZZ4. The ZZ3 and prior versions of the ZZ4 will require the complete kit for the upgrade.
PROVIDED youve got a 3.73:1 rear gear and a manual transmission or a 3000rpm stall converter you can do better, but the drive train must match the much more aggressive cams operational rpm band, with its longer duration and youll need better springs with greater clearance to work correctly
viewtopic.php?f=52&t=82
viewtopic.php?f=52&t=181
example
I hope this is the right place to ask this question. I've got a stock zz4 350 with the Accel DFI Gen VII. Being stock, it has a "carb" camshaft. What is the difference between this and an "EFI" camshaft? Why is one better for EFI? Would I see appreciable perrformance or efficiency gain?
Thanks in Advance!
your carb cam timing is slightly different than the similar engine with the ideal EFI cam, but it won,t be a huge change as the cams LSA (LOBE SEPARATION ANGLE, DURATION and LIFT would be changed on an efi engine mostly to make the sensors for the efi read their data more clearly
keep in mind the cam was selected mostly for durability and reasonable power not to maximize performance.
heres your zz4 specs
10185071 Hydraulic Roller Tappet (ZZ4 Camshaft)
This hydraulic roller tappet is used on the 5.7-liter H.O. 350 ZZ3 & 4 engines. The duration at lash point in degrees (intake/exhaust) is 275/280; duration at .050†tappet lift (intake/exhaust) is 208/221; and maximum lift with 1.5:1 rocker ratio (intake/exhaust) is 474/501. Valve lash is zero/zero and lobe centerline is 112 degrees.
http://www.gmperformanceparts.com/E...=ZZ4350&engine=ZZ4+350&sku=12499712&engCat=sb
G.M. says youll get 40 more hp swapping to the HOT CAM
12480002 Hot Cam Kit (LT4)
This off-highway camshaft kit has the major valve train component to convert production LT1 engine for showroom stock racing, or hop up your small block Chevrolet V8 that was originally equipped with a roller tappet camshaft. The 1.6 roller rockers, light weight valve spring caps, special designed valve springs and hot camshaft offers a significant gain in horsepower at a reasonable price. This kit includes the following items: one camshaft P/N 24502586, 16 roller rocker arms kit P/N 12370839, 16 valve springs P/N 12551483, 16 valve caps P/N 10212808, 16 valve keys P/N 24503856, 16 valve spring shims P/N 10212809.
Technical Notes: This kit does not include roller tappets. If your engine already has roller lifters, you can use them with this kit, but always check for wear and replace if needed before installing this kit. If you are building an engine from a bare block, you can use the roller lifter kit P/N 12371042.
Special Note For ZZ4 Owners: This kit is worth 40HP more when installed in a ZZ4 which will boost the horsepower from 355 to 395, but the ZZ4 comes with the most of the LT4 HOT Cam Kit components already installed. The camshaft and lifters are all that are needed to complete the LT4 Hot Cam conversion on the ZZ4. The ZZ3 and prior versions of the ZZ4 will require the complete kit for the upgrade.
PROVIDED youve got a 3.73:1 rear gear and a manual transmission or a 3000rpm stall converter you can do better, but the drive train must match the much more aggressive cams operational rpm band, with its longer duration and youll need better springs with greater clearance to work correctly
viewtopic.php?f=52&t=82
viewtopic.php?f=52&t=181
example
