I had a local machine shop put together my setup for me a while back. Now, When I blew the motor and noticed that I had spun a bearing on 1,2,4 and broke the rod completely off cylinder3 causing it to go out the front of the block. I have a few reasons in mind why this happened. I noticed that the "tangs" on the rods is on the intake side of the motor. I'm in the stage now of putting my new setup together and I'm asking advice on which side do the ?tangs" go and everyone is saying the front of the motor which is the (exhaust side). Can this cause me to spin a bearing or even put premature wear in the motor leading to failure? The setup saw 15 pounds daily, blueprinted at the time of assembly. I also noticed when I took the oil pump off and opened it that it had scoring in it as if it was starving for oil...

 

I'm not sure what rods you are using so I can't comment on which direction they go. However most rods have an oiling hole in the top that is designed to squirt the underside of the piston and lubricate the wristpin. If put in backwards the oil will fight to flow due to the movement of the engine. Direction does matter.

If you were putting a stock piston/rod assembly in then the pistons really only go in one way. If put in backwards they should hit the valves, but not always. The reliefs are bigger on the intake side than the exhaust.

I would call the manufacturer about the direction the rods and pistons go in. They could be pressed in wrong, which sucks because you ruin the wristpins pushing them back out.

 

Also is the oil pump starving of oil or did it get dirt in it. Many people don't properly clean the oil passages in the crank and block after hot tanking it. It sorta sounds like you got a lot of dirt in things and ruined the motor. I bet your head and cams are all kind of fucked up.

 

At the time of that motor being built I had CP pistons and Pauter rods. When I took the rods and pistons out. I noticed that the ''tangs'' are on the intake side. When I did a search on the site I noticed that everyone was saying the ''tangs'' go on the exhaust side. This sucks if it was really pressed on wrong.

The oil pump and everything was installed by the machine shop so I couldn't tell you if it was dirt or anything that had to do with it scoring up after a while, but I had 4000 miles on the motor when it went....