MikeSammy

So this is the problem I am runnign into. I was rebuilding my 350. I rerung the pistons and put all new bearings in. The crank was ground .010 so I had .010 bearings. The crank turns freely with no piston on it. The crank will turn with the pistons hand tighnted to it, but when I torque the bolts the crank will no longer turn. I pushed so hard to turn the crank the engine stand almost flipped over. I only torqued to bolts to 35 even though they are supposed to torqued to 45 since they are 9/16 nuts on them. When loose the crank turns easily. I did oil the cylinder walls, bearings, pistons, and crank.

Davidgou

iTrader: (2)

It's always better IMHO to measure all clearances with plastigage. There may be something wrong with the clearances, ex. wrong size bearings? It's not supposed to be that hard at all.

zraffz

Sounds like something is wrong with the rod bearings.

Not to mention a rotating assembly without heads on it and no accessories should turn very easily... all you are moving is the rotating mass, you shouldn't be fighting much friction.

Apeiron

What was ground .010? The mains, or the pins?

MikeSammy

all parts for the engine, besides cam, were ground .010. I have a set of standard bearings for the pistons, should I try these

Sparkytfl

What are you using to lube the bearings? I used this stuff http://www.summitracing.com/parts/SLP-55-400/?rtype=10 and it was so sticky the engine got very hard to turn.

MikeSammy

I use regular engine oil. For the cam I had used this oil that was sticky and now I can't turn the cam either. So for the pistons I just stuck with regualr engine oil

AlkyIROC

No, you should measure the parts first to check to see what the specs are. Then use the appropriate bearings with plastigauge to check clearances. When installing the rods and pistons, do one at a time and check rotational torque after torquing the rod bolts. Each piston should add a few more pounds of torque. Something like 10 pounds per piston. One or all rod bearings may be too tight. Checking each rod as it's installed can let you know if one is too tight.

Are the rods installed on the crank properly? The chamfered side of the rod goes to the side of the crank journal as does the rod bearing. The pistons/rods need to go into the cylinder properly. It's easy to mix them up, install a piston/rod upside down, wrong side etc.

scamaro355

so what were your bearing clearances on the rods bearings?

MikeSammy

I had read in a book that on the pistons with the 4 reliefs the little notch on the side must go toward teh front of the engine where the timing gear are. Should I put it the other way.

Apeiron

That's right, but you have to make sure you have the right bank pistons on the right side and the left bank pistons on the left side. When properly installed the rod bearing tangs will be pointing "down".

MikeSammy

Well not all the rod bearing tangs point down, but I had put the pistons back the way I took them out. I heard that you must put the pistons back in their respecive bores.

scamaro355

yeah as long as the pistons arent new in an old bore... alot of time the bore will go slightly egg shaped over time

Apeiron

You've done something wrong. The rod bearing tangs must all point down.

Grumbles

Sorry to chime in and hijack but what the hell is a rod bearing tang?

Apeiron

The little bump in the edge of each bearing half that fit into the notches in the cap to keep the bearings from spinning.

MikeSammy

I guess who ever owned the engine before me put them in wrong. Tomorow I will remove all the pistons and check for any problems.

cuisinartvette

Bet a rod cap isnt on straight. THey can appear to be but if they are off just the slightest bit the bearing can bind up, can also do it if the rod is torqed down and the rod isnt straight in the bore (there will be a little side to side play) Force it and youll damage something. Double check an assembled rod to check the sizing of it..put the beaing in measure again, measure the crank then subtract the clearance to see what you have. Check measure and check again
Do one rod ata time then rotate the motor

mlynch001

If they mixed up the pistons and had them in backwards, they may have mixed up the rod caps. Are the caps and rods numbered? I would check the big ends of the rods to make sure they are not out of round or mixed up. GM did not number the rods and caps, you have to do that when you tear down. Rod caps go on with the bearing tang in the rod and cap on the same side of the rod.

Install one rod at a time. Torque the cap and see if the rod will slide freely from side to side. If it will not slide then you have a problem with that rod. Do one side at a time, and check each one as you go.

MikeSammy

if I have tghe engine on an engine s tand and it is upside down, looking at the engine standing from the front, then the bearing tangs should be on the left for the left side and and the right for the right right, am i correct.

Apeiron

They'll be facing "up" with the engine upside down, or you could think of it as them facing "out" towards the outside of the block, as well.