Assembling my 3400

[92cavquest]

I'm been putting together my 3400 this weekend and I've run into a problem. I put in the main bearings, installed the crank, pu in the other half of the bearings and then put on the main caps. Torqued them to spec and now the crank won't turn. I took them all off and put them in one at a time (turning the crank after each) and it seems no matter which two I put on it causes it to bind.

Anyone have any ideas?

Also, what timing chain, dampner, and tensioner does everyone recommend?

[34blazer]

have you measured the journals?

[whatever]

Sounds like you have the wrong bearings. maybe bearings for a ground {turned}crank?

Mark.

[92cavquest]

I have not measured the journals. The crank was out of a very low mileage engine and the old main bearings were in very good condition. I ordered stock sized bearings and installed them. I'll run the part number on the box tomorrow and see what I get. Probably should pick up some plastigauge too.

[92cavquest]

Here's the info on the box:

7242ma .25mm
"A SERIES"

Napa Number
ms-2037a-.25mm

[Alxsmt]

i have no idea other than what has been said. when you assemble an engine always check the clearance on EVERYTHING. its always a good idea, you never know if a machine messed up somehow or a got a misbox

[TiredGXP]

Here's the info on the box:

7242ma .25mm
"A SERIES"

Napa Number
ms-2037a-.25mm

The .25mm noted probably means that the bearings are .25mm (.010") undersize - that would explain why a stock journal crank won't spin.

cheers

[92cavquest]

You're correct. I just looked it up. I'm gonna get the right ones today. Dmn those guys at the parts store. I told them I needed stock replacements.

[tractorman]

Lesson learned: never trust a parts guy. If at all possible, it's best to verify that you've got the right stuff before leaving the store. I've been handed the wrong part more times than I care to recall.

At least you caught the problem before assembling the engine. Several years ago my brother put together a chevy 350. It has a .020" under crank... but he put in standard bearings. It didn't hold together long.

[ForcedFirebird]

It didn't hold together long.

Man, the lessons learned the hard way over the years...

[92cavquest]

Alright, new question. I'm ready to install the pistons and rods. I didn't disassemble this engine myself (had some help) and the guy that took it apart isn't in the country right now. On the connecting rods, do the bearing tangs go on opposite sides of the rod or on the same side?

Common sense tells me opposite sides of the rods.

[92cavquest]

Can anyone please confirm this? I'd like to be in the garage finishing my bottom end and watching the superbowl.

[ForcedFirebird]

The notch in the pistons have to face the front of the engine.

[92cavquest]

I'm asking if the bearing tangs on the connecting rods go on the same side of the rod or are they on different sides of the rod. I can get a picture if need be.

[ForcedFirebird]

I'm asking if the bearing tangs on the connecting rods go on the same side of the rod or are they on different sides of the rod. I can get a picture if need be.

Oh, sorry misunderstood.

Opposite sides, they are "anti-rotation" tabs to keep the bearings from spinning.