Got mine at rock auto for arround 300$

 

Pulled the crank. Bearings closer to the front of the engine were more worn than the others. Is this just because of the knocking? Or does it indicate something else like a balancer?

 

When you say "Bearings closer to the front of the engine" are you talking about the mains, rods or all of them ? Sounds like you need to investigate all of the machined tolarances as well as oil clearances in this engine before reassembling it again, something has caused this and you need to get to the bottom of it before putting anymore new parts in it. I would also take the cam back out and check those bearings as well.

 

Mains and rods had more copper showing near the front.

 

Was the crank checked for runout ? A lot of the time rod bearing failure can be traced back to the main bearing that was feeding oil to it. Anything that comes off the main bearing or throught the main bearing is fed right down to the rod bearing.

 

No I didn't check runout the first time, but will this time around. Should I re-measure all the parts, or just plastigauge them?

 

Did you have the crank, rods and pistons balanced? With the balancer and flywheel?

 

Nope. It didn't vibrate much though

 

Plastigauge is not going to be of any help here. I would try to borrow or buy a bore gauge & mics that read in .0001". You also need a dial gauge with a magnetic base to check the crank for runout. Because of the trouble you have had I would leave no stone unturned now. Torque up the main caps with no bearings, check size, out of round & taper, do the same with all the rods. If the bores all check out to be within .0003" then move on to the crank. Chamfer all the oil holes. Mic every journal to be sure it is within specs. Record all the journal sizes. Put all the bearings in and torque to specs. Set your bore gauge up. Refer to your journal sizes, check bearing clearance, check for vertical taper in the bearing.
I would get it balanced if you have changed pistons. The factory balance job is not going to cut it. A crank that is out of balance will tear the main bearings out in time putting you right back to where you started.
You make your own luck in engine building. Some people get lucky just throwing a bottom end together but with the price of parts and the aggravation of having to do things over for the price of a few measuring tools that can be picked up used on ebay for half of the price new it will pay off in the long run.

 

The only thing I don't have is a bore gauge. By that do you mean one of those springloaded T shaped things?

 

This is a bore gauge. Snap gauges can be used but a bore gauge is more accurate. The small mics are ball mics that are used to check the thickness of a bearing insert. Most of the time they are all the same but sometimes you will find one that is a little different and can be used to take up or remove some clearance. When you are dealing in .0001" every little bit can help.

 

why not just regrind the Crank?? normal bearings for this are no more expensive than normal. the 1-2-3 thou incremental ones I can understand but not the standard -10 (and more) thou types used in a typical regrind situation.

 

I'm trading my crank for one reground with matching bearings for $180. Is bearing selection a big deal? Or are the stock bearings fine? 375 hp give or take in a 74 F250 4wd

 

Thats a pretty good deal, but what would it cost to regrind your crank and buy a set of bearings for 30-40 dollars? I'd ask the machine shop about the bearings. All about the groove, full versus half-cant remember which way it goes for race vs standard- I even think you can get 3/4 to split your bets. Just remember (and I think this is still true) all the engine bearings in the world for these type of things are made in only 2-3 factories. They just repackage them. There is a factory in Tasmania Australia, (ACL), one in Israel (king) and maybe one in the states. Everybody else gets them from one of these suppliers.

 

I read somewhere exesive belt tension could cause front main to wear prematuraly on the long run. just my .02