Engine Balancing

[Bumpysbro]

Im building my engine this week just waiting for the parts to come in. im getting new pistons, maybe new rods and a new crank. when does balancing the internals have to be done? ive never done this before and always wondered when or why it has to be done. thanks
Jon

[Bochek]

well when i did my f2t i got a very accurate scale.... and weighed each assembled unit. (piston, rings, bearings, rod, cap, exct)

i then removed enough material from the end of the connecting rod to make them all match in weight. (theres usualy a large chunk of metal right at the bottom of the connecting rod, take it off there)

- Bochek

[jaydog5678]

Im building my engine this week just waiting for the parts to come in. im getting new pistons, maybe new rods and a new crank. when does balancing the internals have to be done? ive never done this before and always wondered when or why it has to be done. thanks
Jon

It depends alot on the parts. Some aftermarket companies claim that the weight differences btwn their parts are so close that no balancing is required. Aftermarket con rod companies (good one's) usually don't require this. Piston manufacturing companies are the same way. The crankshaft should be balanced with the flywheel, clutch assembly, and crank pulley all at one time. This is the correct way to balance the bottom end. Some machine shops can do this for you and some cannot. Most rebuilds will not require the entire rotating assembly to be rebalanced. It does depend more on what you want the engine to do. If you are building a super 300hp, 9k rpm monster, then balancing will be required. If it is a stock rebuild making stock hp, then balancing is not as critical. Balancing does help engine longevity and keeps bearings from wearing pre-maturely. An engine that is balanced will reduce bottom end vibration and noise in some cases.

[Bumpysbro]

ive read about internal and external balanced engines. which is ours? oh and does the flywheel position change the balance. the flywheel was removed by my brother without me knowing and did not mark how it went on. does it matter a great deal? thanks for the info jaydog, its just a stock rebuild nothing big. getting new internals, and rebuilding thats about it.
Jon

[jaydog5678]

Internaly balanced.

In your case then, no balancing is really required. The flywheel position does not change anything so you don't have to put it back on exactly the way it came off.

[Bumpysbro]

ahh awesome glad to hear that. oh and you have one nice looking car i have a white 95 rs. how long have it had it?

[jaydog5678]

Thanks B. The car was family purchased new in 94. I've technically owned it since 96.

[Bumpysbro]

thats cool, ive owned mine for almost 2 years now. just about done putting her back together. do you work on cars as a job or just a hobby? oh and always good seeing another white mx3 i dont see too many of those around

[jaydog5678]

Yeah, my full time job is working with Hondas and Acuras as well as Toyota, Lexus and of course Mazdas. Working on mine is just one expensive hobby. I see a few white mx-3's here and there. Not many Mx-3's seem to be left in a world of truks and suv's. The most popular color around here seems to be green.