Bore notching

73Wagon · Post by **73Wagon** » 29 Jul 2013 23:57

I putting together an L18. The head currently has 42mm intake valves and 33mm exhaust valves. I am planning to have the head ported and machined for 35mm exhaust valves. Im also planning to run a shadbolt M445 cam, .510" lift at the valve. The bore will hopefully remain stock at 85mm. How to modify Datsun ohc engine book mentions that bore notching may be required for 83 - 85mm bores using higher lift cams. How to modify Datsun 510 engine and chassis says that your safe with an L18 (L16 would have clearance issues). Does anyone have experience running large valves in an L18 or L20B with a 445 or 780? Did you have to notch the bores? Thanks guys. Soon I'll mock the head on the block and have a look.