Ford motor help

I have a 1963 f100 unibody with a 1971 mercury cougar cobra jet 429 in the truck...well its out of the truck for a trans rebuild and new main bearings...puting a new oil pump on it as well. I would be a fool not to do that. The engine, the farther I dig into it the weirder it gets, a retainer clip, on the top of the rocker broke some how and im lucky it didnt go down through the motor and mash anything up. the fly wheel that was bolted onto it was for a 351-400 and that was a balanced fly wheel that has a crack though it. the harmonic balancer is un balanced and the crank in the engine it has the holes drilled into the counter weights but no plugs welded in I honestly dont know if its balanced. So my question would be: is the engine internaly balanced or Externaly balanced?

Thanks Bryan

 

The 1968-1973 production run of 429's were all internal balance engines.

 

Wouldn't the crank have plugs welded into the counter weights tho? all their is are holes drilled where plugs would go...

 

I have seen engines just drilled out for balance, removing material.

 

I have seen alot more Ford internally balanced motors with holes in the cranks then with plugs welded in. Remember, on an assembly line, it is alot cheaper and quicker to drill holes to balance a crank then it is to weld on extra material. So a bit of extra material in the casting mold to get removed later is well worth it.

 

On the balancing, it depends on whether they needed to add or subtract weight. Drilled holes to lighten an area, drilled and filled with heavy metal to add weight. Nothing unusual on either.

As for the flywheel, not sure what is going on there since the crank diameter where the flywheels mount are different, 3.142" for the 460 and 3.750" for the 351M-400

 

looking at the crank the front counter weight and the back counter weight both have a hole drilled in them to balance it, the flywheel was balanced also and the harmonic balancer is I beleave neutral the motor i beleave was redone in 1999 well before i had the truck the year is stamped in the bearings.. bearings read 12-99.

 

Holes drilled a 90 deg. to the crank are usally to lighten. Heavy metal holes are drilled lenght ways to the crank so they won't fly out with centrifugal force.