BLOCK CRACK FIX
On 400 SB Chevy blocks, the deck is the weak link – they have a tendency to crack between the water holes. I have found a successful fix for this.
I drill and tap the water holes for tapered pipe plugs. Once they are sealed and threaded into the block, the block is surfaced. Then we drill new water holes through the pipe plugs.
If you are shot blasting an engine block but want to protect the crankshaft housing bore surfaces, you can install some used upper main bearing shells in place, then secure them to the block with a threaded rod or machine screws with a nut up in the cam housing tunnel area.
D and D Auto Machine
CAM BEARING BORING TOOL
Camshafts will often times not fit into newly installed cam bearings. Since most factory cam bearings are bored in place, cam bore alignment is not an issue from the factory, but becomes an issue with finish machined bearings.
I take a die grinder to an old camshaft to make a boring tool by cutting two slots in the bearing journal. Now, I can slowly hand turn the tool – as it feeds into the block it leaves the new bearings the perfect size so a new cam can slide straight in easily.
Bill’s Custom Engines
RELUCTOR WHEEL INSTALLATION
Many late-model engines, like the LS series GM V8s use a press fit reluctor wheel as a crankshaft trigger. When the need arises to swap the crankshaft reluctor, some companies sell a tool for approximately $200.
Taking one off is as simple as knocking off a timing gear, but putting one on requires proper alignment. I heat up the reluctor wheel in an oven, then use a homemade flywheel fixture fitted with two rods to line it up in the right location on the crank as it cools.
Jeff’s Auto Machine Shop
REDUCED RADIAL WALL THICKNESS BY DESIGN
The use of steel in the upper compression ring has many advantages. Steel provides 35% more strength, weighs 30% less and increases the resistance to side wear, which is seen on the newer-model engines. Another feature from the increased steel strength is the resistance to breakage during improper ring installation.
The increased strength of steel over grey cast iron means that necessary tension can be achieved with less weight. This increased strength feature allows production of high quality rings with reduced radial walls. Increased strength, reduced radial wall and lighter weight all improve the performance of the compression ring. Newer engines have higher RPMs and lighter rings that are more stable in the groove. Improved sealing is achieved by the steel compression rings conforming to the cylinder better.
Original equipment piston ring grooves and ring designs take into consideration the ring back clearance. It is thought that minimal ring back clearance improves overall performance of the engine. The power stroke gases energize the compression ring increasing the pressure against the cylinder wall, decreasing blow-by and increasing power. The concern that increased ring back clearance will adversely affect engine performance has been dismissed by engine testing. In summary, modern engines are insensitive to increased ring back clearance.
The important features of piston rings are the correct axial width and optimal gap. The correct side clearance is typically in the .0015” – .0025” range. This is adequate side clearance to allow the compression gases to energize the ring to operate properly. Builders can replace cast iron top rings with steel top rings and get all the benefits discussed without fear of the new reduction in radial wall depth.
Engine Pro Technical Committee with special thanks to Hastings Manufacturing Company