The Dirt Forum for More Information
Topic: connecting rod direction
Total posts: 9
posted March 15, 2001 10:27 PM
Eng. newbe I have aftermarket rods 4140s
with the small nubs on one side of the big
end.do these need to face front or back
of a sbc. Rick
Total posts: 219
posted March 16, 2001 02:40 AM
rdirt, I will answer the question for you. But first I will say that if you aren't sure on the proper installation of a set of rods I would recommend getting someone that knows and understands the proper way of assembeling
a motor to show you how to do this......I don't say this to make light of yourself. ANY motor is a investment and you as a racer need to get full and complete use of this investment........PLEASE, FIND SOMEONE TO SHOW AND HELP YOU THE FIRST COUPLE TIMES YOU BOLT A MOTOR TOGETHER.
I will say that rods can only go in a motor one way to fit properly. Start off by making each piston for each hole.......I do this with a black marker myself, just write the bore number on the top of the piston. The next thing is to hang the rods on the pistons. The pistons should be standing on-top the bore and hold the rod like it should be in the motor. The tangs for the bearings go toward the bottom of the crank, always staying on the bottom during rotation. Take that marker and put a line on the rod face the goes to the outside, also do this on the piston........this way when you flip the set around to put them together you don't spin one a half turn........The next step is to insert the bearings.....these have a top and bottom half.......look at the stamping and read them........make sure you get the top half in the rod and the bottom half in the cap........this is VERY important......RACING bearings are chamfered for the .125 radius in the crank........if you do this wrong the chamfered part of the bearing will be wrong side out when installed..........
When you are all done the #1 and #2 rods that sit on the same journal of the crank will have the chamfered parts of the bearing facing the outside of the journal ......the center of the journal won't have the chamfered part..............
In closing I will put this is order as easy as I can and as simple as I can.
1. mark all pistons for which bore, write the number on the top of each piston.
2. hold the piston above the hole that it belongs in and hold the rod under the piston with the tabs for the bearing facing down.
mark the piston and rod on the same side, as to not confuse yourself later.
3. install bearings into rods, making sure top in rods, bottoms in caps.
4. double check your work by holding each piston above the bore......ALL CHAMFERED SIDES WILL FACE THE FRONT ON THE DRIVERS SIDE, WHEN INSTALLED CORRECTLY.......ALL CHAMFERED SIDES WILL FACE THE REAR OF THE MOTOR ON THE PASSENGER SIDE.........
All this assumes we are talking about your standard V-8 chevy, with a racing bearing and floating wrist-pin..........because if they were press fit we wouldn't be talking about this.........LOL
If this has confused you too much let me know I will try a different approch