09-10-2022, 11:27 AM
Hi
When I rebuilt my 2 bearing engine many years ago, I found that I had rods (with caps) of 318, 361, 363 and 372 grams. One of the many joys of the occasional repairer who has to learn things the regular repairers will probably be familiar with. I assumed that the 318 was a light pattern and there was no way of adding about 47 grams to bring it in to line with the average of the other three. I put the 318 aside and luckily managed to source a 370.
By assembling the engine with 370 and 372 on Nos 1 and 2, and 363 and 361 on Nos 3 and 4 I figured that balance would be acceptable. It feels OK for a road engine that rarely goes above 4000 RPM.
The density of cast iron is about 7, so 15 grams is about 2 cc. Quite a lot to grind off, but not impossible if it is done over a wide area. A 5/16 inch 40 thou thick steel washer is only about 1 gram, so you might struggle.
Maybe slimming down the sides of the white metal would help ?
When I rebuilt my 2 bearing engine many years ago, I found that I had rods (with caps) of 318, 361, 363 and 372 grams. One of the many joys of the occasional repairer who has to learn things the regular repairers will probably be familiar with. I assumed that the 318 was a light pattern and there was no way of adding about 47 grams to bring it in to line with the average of the other three. I put the 318 aside and luckily managed to source a 370.
By assembling the engine with 370 and 372 on Nos 1 and 2, and 363 and 361 on Nos 3 and 4 I figured that balance would be acceptable. It feels OK for a road engine that rarely goes above 4000 RPM.
The density of cast iron is about 7, so 15 grams is about 2 cc. Quite a lot to grind off, but not impossible if it is done over a wide area. A 5/16 inch 40 thou thick steel washer is only about 1 gram, so you might struggle.
Maybe slimming down the sides of the white metal would help ?