mcollinstn

Yeah, that's the thing.
There are some blocks that are machined a little differently than others. While there are some definite "trends" in years/etc that you can use as a rule of thumb, marine blocks can come from different batches and different warehouses, so I don't like to tell anybody a particular year is safe.

If you know what you are looking for:
Good body containment from base circle to max lift.
Good dogbone engagement from base circle to max lift (and not bottoming out the notch).
The "waist" of the lifter remaining accessible to the pressure port from base circle to max lift.

Then you can determine if your stock lifters will work or not. It's not difficult to tell, you just have to put the cam in the block and drop a lifter in and play with it to see.

There ARE blocks where the oil hole gets covered up, and there ARE blocks where the lifter can get scary close to dropping below the dogbone plate with reduced base-circle cams.

If lowbuck has many hours on his existing lifters, he will want to replace them anyhow. Extended lifters are more expensive but he will have to check his block/cam/lifter setup to determine if the standard lifters appear to be safe.

If they ARE, then stock GM lifters are priced reasonably and work well up to around 5500 rpm.


MC