Roothawg (9/15/2010)
Just curious what you would build if you were starting from scratch and what mods you would do to the Yblock?Your basic rebuild where you bore for new pistons and turning the crankshaft restores the critical clearances back to spec. Align honing the mains and machining the decks are also recommended. The block modifications themselves for what your wanting to do is going to be around the oiling system. If pressurizing the rocker arms, then putting a small hole in the block behind the cam thrust plate and grinding a matching channel in the cam thrust plate to direct oil to the timing chain would be recommended. Port work on the heads always helps but don’t overcam as you want to keep low end torque strong for towing.
The other oil mods reside around an adequate amount of oil to the topend of the engine. One option is to insure that the center groove on the camshaft is wide and deep enough to do this. But make sure you’re using a ‘hard’ set of cam bearings. Using a ‘soft’ set simply allows the camshaft to wear into the cam bearing material and shut off the oil supply to the top simply by pinching off the oil supply at the center cam journal groove. The way around this is to just put a groove connecting the three holes in the block behind the center cam bearing which circumvents the oil having to travel in the groove of the camshaft. Doing this may require the use of a restrictor at the top of the head as this particular mod does increase the amount of oil going to the top end significantly.
Here is a collection of links going into some of the various oiling mods.
Center cam bearing
Grooving the center cam hole in the block
Pressurized rocker shafts
Pressurized rocker shaft more
Pressurized timing chain oiling
Rocker arm overflow tubes Cons
Rocker arm overflow tubes Pros
Rocker arm overflow tube More Pros
Timing chain oil trough
Adding lifter valley holes for camshaft oiling
Drilling additional holes for oiling and/or venting
Valley holes for aiding crankcase evacutation

Lorena, Texas (South of Waco)