• Dana

Connecting Rods

Updated: Jun 27, 2019

Just a quick update on progress. I'm working on the bottom end of the engine. It's a little slow going because of my work schedule but also I keep running into tools and parts I need. My main goal now is to finish the flywheels, balance them and true them. But in order to do that I need to get the connecting rods built up.

Job one is to get the big end races installed into the connecting rods. The rods I bought already had the small end in and honed. The brand new races I had were at 4 to 5 thousands to big for the rods. So I had to hone the connecting rods too size, and to do that I needed to order and wait for the right set of stones.

My handy dandy 'Rod Race Pusher'

The other tricky part was you can't just push the races into the female connecting rod. They're pretty thin and they'll bend if you're not careful. So I spent another full day making the tool to push them in. Once again I spend all day making a tool and 5 minutes using it. Here's my 'Rod Race Pusher' tool.

The tool has four parts, from left to right. The 'Base', the connecting rod sits on the this part. The 'Guide', this part fits inside the rod and is turned down to 0.001 less then the diameter of the race. The top 0.25 inch is turned down more to fit inside the race. This keeps the race square with the connecting rod as you push it in.

The 'Push Plate', this is flat on one side and has a 0.030 indent on the other. This sits flat on the race and does the pushing. I put a 0.030 indent on one side because the male race needs to have a 0.030 clearance on both sides. And finally the 'Pusher'. This is turned downed to the inside diameter of the race. This keeps everything square and flat as you are pushing the races in.

I'll upload a drawing for it later so I can remember how to use it again next time.

After I got the races installed, all I had to do was measure the diameter of the races and crankshafts and pick the right size bearings. But the races shrank after I pushed them in and now they need to be honed out again. This time I had the stones I needed and I was able to hone them to size with out much trouble. It still takes me forever though, I'm so worried about taking out top much material that I stop and measure way too often. Better slow and safe then fast and overshooting the mark.

Anyway, I got everything measured and fitted correctly and here's my new connecting rods.

My new, ready to go connecting rods

Now on to balancing the flywheels.

Build Notes:

Front Connecting Rod Rec Weight 163 grams

Rear Connecting Rod Rec Weight 165 grams

Front Connecting Rod Rot Weight 259 grams

Rear Connecting Rod Rot Weight 415 grams

Male Rod ID : 1.4990

Female (1) Rod ID: 1.4990

Female (2) Rod ID: 1.4990

Crankshaft: 1.0001

Bearings : 0.2490

Clearance : 0.0011