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Discussion Starter #1
I´m being orking on my engine. is a 302 out from a 79-80 Ranger F150. Is not the best in terms of performance.

I must to send the ckrank to the machine shop and I want to know if I must to make some mods to reach some 7500 RPM w/o burn the crank. I´ve been thinking to enlarge the diameter of oil ducts and make a "channel"(sorry, I don{t know the exact word) on main journals. Also a good balancing work. It must be maded with balancer damper and flexplate and clutch or bare crank only?

thaks ofr your answers.

Regards,
Mariano

PS: what about nitrure treatment?
 

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The machine shop can machine the journals and teardrop the oil gallery holes. As long as the crank is straight and free of cracks you are fine. You will need the pistons, wristpins, rings, rods, bearings, flywheel and damper to balance the assembly. The person doing the balancing even factors in the oil in the rotating assembly.
 

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The term is "Cross drill and Champfer the oil holes". I would see if they would do a "race" Champfer which is going across the journal trying to get the most oil to the bearing surface. Now, with that being said, I am not sure if they cross drill SBF cranks. Not sure if it weakens them too much. I have my BBO cranks done that way and have no problems, but the SBF crank is alot smaller....
 

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If you're looking to reach 7500 rpm with a cast crank it must be absolutely straight to begin with. The machine shop can measure that for you and correct it if it's only off a little. Chamfering the oil holes is also important. Have the journals radiused when ground undersize, that will increase the strength. Lastly, I would seriously consider nitride treating and micro polishing. The nitride will increase the hardness of the bearing surface, and the polishing will reduce friction.
 

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Discussion Starter #5
Thanks alot for your answers. I must to rectify it, so I want to make that job at one time.

Cheers,
Mariano
 

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Mariano,

As someone who has built many of these type engines over the years, my best advice to you is to stick to the basics, but perfom them to perfection ;). To help oiling/longevity at high rpms, try the following, if you're using all stock rotating parts (crank/rods):

Have the crankshaft indexed (this ensures the throws are in the right relationship to each other), ground undersize with the proper oil clearance for your application (usually larger than OEM) and champher the oil passage openings. I also relieve any casting flash lines evident. The proper procedure is to magnaflux the crankshaft, blueprint it (check journal sizes, indexing, etc), then do your work (champher oil holes, remove flash), then send it to the grinder; lastly, once it and the reciprocating and rotating assemblies are ready, send the package to the balancing shop.

Modify the OEM rods by removing the forging flash, drilling the big ends for 11/32" rod bolts and modifying the small end for floating a tool steel pin (steel on steel).

Use grooved main bearings. Bearing materials should be of the highest quality available.

Keep the reciprocating assembly as light as possible. I used lightweight pistons, narrow piston rings, and thin-wall tool steel wrist pins in my engines. I also used a SFI certified harmonic balancer and flexplate/flywheel.

If you can run a solid lifter camshaft and use roller rockers, you can restrict oil flow to the lifter galleries. This is a somewhat complex process which took me a number of iterations to perfect. When completed, it did allow reliable 7-8K rpm operations using a blueprinted OEM-style Hi-volume oil pump. Oil pressures in the 50 psi range were all that was needed for reliable operations.

Of course, all machining operations should be completed to a routine racing standard, which is more stringent than most rebuilders use. You'll need a shop which has the proper equipment, expertise and is willing to cooperate with you in achieving your goal.

I built reliable engines of this type with OEM parts long before all the nice aftermarket stuff we have now was available, and you can too. It just takes some skill and time, and having a good shop on your team.

Good luck!
 
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