I'm finally getting my HP273 back together. I bought this engine for $225 a while back and have been getting it into shape. The engine was rebuilt around 1980 or so and run very little. The crank, pistons, cylinders, etc were all in nice shape, but there was a fair amount of carbon and sludge inside so the engine was completely torn down and the block jet washed. I'm reusing the pistons, rings, the upper bearing main bearings and the rod bearings. I had an extra set of .010" undersize mains so I stole the upper main shells and used them as lowers so I have fully grooved mains. I polished the tops of the pistons in hopes of making more power and collecting less carbon. A thermal coating would have been better, but this is a budget build. The cam was a wimpy Crower hydraulic that's getting replaced. The factory style domed pistons are forged. I have a feeling the engine wasn't used much as it likely pinged due to the high compression ratio and short duration cam. The exhaust guides were worn so they were replaced with bronze and both intake and exhaust guides were machined for positive seals. I also sprung for hard exhaust seats. It's too bad these 273 heads have such a lousy exhaust short turn, but that's the breaks.

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Joshua

Are you going back to the stock mechanical valvetrain or just getting a hydro setup?

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82 D150-225/727
02 Dakota-3.9/5 speed
87 GMC C7000-8.2 Detroit Diesel/5+2

The engine had a juice cam with the shorter pushrods and the stock adjustable rockers. The valve gear is in great shape so I'm going to reuse it. I have the correct length pushrods for a mechanical cam, but haven't decided if I'm going to use the 230° @ .050" lift mechanical cam or the 230°/236° @ .050" hydraulic I have. I have 3 solid lifter cams and two hydraulics, but only the two I mentioned are candidates for this engine. Hopefully the one I choose will clear the stock valve reliefs. If not I'll have to spend another $70 at Oregon Cam Grinding and get something that will work. The 273 needs a wider LDA than a 318 or 360 for optimum torque which also helps with valve to piston clearance. The juice cam is ground on 110° lobe centers and the mechanical is 108° so I'm leaning toward the hydraulic.

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Joshua