I plan on changing the rod bearings in my 352 I think they are knocking and I figure it wouldn't hurt to change them. to replace them without having the crank machined do you use oversized or undersized bearings? Thanks Eric

 

Actually, you'd use the same size. The bearings should be marked on the back side with std, 010, 020 or something like that. Inspect the bearing and see if it is worn. Before you remove the bearings, buy some plasti-gauge and check the clearance. make sure you clean the area, place a piece of the plasti-gauge in, retorque the cap and measure the plasti-gauge. Do this again with the new bearings and if they are within the specs, you haven't found the problem.

While you have the oil pan off, use a flashlight to look up into the cyl and look for scaring. move the piston to the bottom and look for scaring on the skirt of the piston as well, check to see if you can move the piston, it shouldn't rock much and shouldn't twist at all (do this before and after you change the bearings).

Proper clearance is the most important thing about bearings, install is straight forward, just line up the tab on the edge and make sure the top one doesn't move after you set it up. the green plasti-gauge is the one you want.

 

I found the problem the #3 cylinder rod bearing was overlaped like there was only half a bearing in there. They are really thin. The crank don't look to bad it is not scratched but is dull does it have to be machined? Thanks Eric

 

If you don't want to remove the crank, you can polish it with string and ultra fine wet/dry sand paper. wrap the sand paper around the crank and wrap the string around that, pull string back and forth to polish the crank. again use ULTRA FINE sand paper.
Install the bearing, use plasti-gauge to check in several different spots, I ruined a crank by not checking the rods enough and assumed they were machined properly on the sides. It's tough to check all areas of bearing clearance, but at least check a few different places. Move the crank to one side, other side and center, and move the plasti-gauge to different spots, this should give you a good idea of the roundness of the crank.

A good mic would be better, you might be able to rent or borrow one.

 

The green plastigauge won't measure the clearance where the rod was knocking. The other one I measured is allawable according to the shop manual. Eric

 

Has anyone used a rebuild kit from PAW? I was thinking about using the rebuild kit they have. I decided since I have to pull the crank and have it machined I am going to rebuild it as soon as I save enough money. I am going to get the block hot tanked, magnafluxed and have them check the cylinders, have new cam bearings pressed in and probably have it align honed. Hopefully I can reuse the pistons an rods if I can I will have new pins put in. If there is anything I missed please let me know. I will let you know how it goes when I am done. Thanks Eric

 

I tore the engine down today and one four pistons the top compression ring was broke in half. There is no scratches, or nicks in the bores. The cam is missing chunks out of the lobes. I am going to have it hot tanked and new cam bearings installed. Eric

 

Sounds like you don't need a kit, just rings, bearings, and a new cam and lifters. I'd pass on PAW because I got bad part from them in the past. Their machining process sucks and I don't like skimping on something as important as proper machining. They are high volume and minimal/poor quality. Just have your crank reground if needed, check piston skirt clearance and see if you can reuse the old pistons. You might consider a performance cam, the price is about the same and they can perk up the engine quite a bit. If you're doing any towing or low-mid range work, Crower and Crane make some good cams for that engine. Don't forget hardened exhaust valve seats if you don't have them already. A new HV oil pump is a good $40 investment as well.