| Compared to a conventional big-block cylinder case, the Bowtie examples have much more meat surrounding the lifter bores. This serves several purposes: You can safely sleeve lifer bores with this setup (necessary with keyway roller lifters or to repair worn lifter bores) or you can install oversize lifters (all Chevys use a rather small 0.840-inch diameter). Further, Bowtie blocks are machined in the valley in any area that is adjacent to the lifter. This is particularly important when it comes to clearance for roller lifter assemblies (hydraulic or solid). Because of this, engine builders don’t have to concern themselves with roller lifter tie bar clearance and other issues when assembling the block. |
Look closely at this image of the main oil gallery. On late-model big- blocks, the gallery is placed up high, next to the cam tunnel. On earlier big- blocks, the main oil gallery was between the oil pan rail and the main journal tunnel. In that case, the block was limited to the amount of stroke it would accept (clearancing the block for big strokes wasn’t possible at times since the builder would eventually “strike oil”). If a connecting rod departs in an early block, it usually takes out the oil gallery. Here, there’s a chance it won’t, since the gallery is so high in the casting. |
