Building Chevy 4.3 liter V6 - 1994 with balance shaft
(→MACHINING AND PORTING) |
(→MACHINE THE HEADS - PORTING) |
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'''HEADS - MACHINE''' | '''HEADS - MACHINE''' | ||
| − | I have removed all the studs and prepared for screw in studs. I'll go with 3/8" studs. The choice of rockers will also be decisive. Aiming at a nice steel roller rocker such as CompCams Magnum Pro Roller Rocker 1,6:1. The geometry defined I'll have the bosses machined for proper height of the studs then the centers bored according to proper alignment from the lifter bores to the valve stems | + | I have removed all the studs and prepared for screw in studs. I'll go with 3/8" studs. The choice of rockers will also be decisive. Aiming at a nice steel roller rocker such as CompCams Magnum Pro Roller Rocker 1,6:1. The geometry defined I'll have the bosses machined for proper height of the studs then the centers bored according to proper alignment from the lifter bores to the valve stems. Most probably I will NOT need guide plates as the rocker arms have stem guides. |
'''CAUTION:''' | '''CAUTION:''' | ||
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The diameter of 9.4 mm is a perfect center bore for a 7/16"-14 thread. | The diameter of 9.4 mm is a perfect center bore for a 7/16"-14 thread. | ||
| − | Last week (OCT 2016) I had the stud bosses machined by 1 mm (0.04") and made a test assembly with some old TRW screw in studs and a new COMPCams 1.6 ratio rocker arm. | + | Last week (OCT 2016) I had the stud bosses machined by 1 mm (0.04") and 7/16-14 threads cut. Then we made a test assembly with some old TRW screw in studs and a new COMPCams 1.6 ratio rocker arm. |
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What we found was that the valve geometry is too far to the exhaust side and I need to lower the axle of the rocker arm. We modified 1 of the studs (on a lathe cut a smaller radius onto the shoulder above the hex to lower the assy by some 3.5 mm total. This just put it about right and withouth the 3/8" rocker arm nut it just barely clears the valve covers. | What we found was that the valve geometry is too far to the exhaust side and I need to lower the axle of the rocker arm. We modified 1 of the studs (on a lathe cut a smaller radius onto the shoulder above the hex to lower the assy by some 3.5 mm total. This just put it about right and withouth the 3/8" rocker arm nut it just barely clears the valve covers. | ||
With this information we'll most probably cut the bosses down an additional 4 mm (0.16") for a total of 5 mm (0.20") to get enough clearance to adjust the valvetrain geometry on all valves. Maybe even a mm more. | With this information we'll most probably cut the bosses down an additional 4 mm (0.16") for a total of 5 mm (0.20") to get enough clearance to adjust the valvetrain geometry on all valves. Maybe even a mm more. | ||
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| + | I will order a set of 16 studs from Summit and go with the ARP 134-7101 7/16"-14 base thread and 3/8"-24 adjuster thread with a protruding lenght of 1.750". With the bosses cut this will end up nearly exactly where the OEM studs stood. | ||
Machine the valve spring pockets and the valve guide bosses for clearance to accomodate the new lift and oil seals. | Machine the valve spring pockets and the valve guide bosses for clearance to accomodate the new lift and oil seals. | ||
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