Help! 360 balancing info has my brain hurting

jimbob78cj

Purchased a 360 to replace my wore out 304 in my CJ when I was an unlearned newb. Purchased as a short block (which appears to have been rebuilt; cross hatch in cylinder walls) with a box of parts. I'm trying to put it all together and trying to find the right parts that are missing from the box. The main problem is I have no balancer or flywheel. I have no info on what this engine came out of, year of manufacture or anything. I have read a lot about these externally balanced engines and that the right flywheel and balancer is important but most forums are conflicting in info (go figure). In searching for a flywheel and balancer, I really just need stock replacements as I don't intend on high rpm racing but primarily low rpm rock crawling, but all I can find is high $$ race quality speciality parts. Budget is a factor also. Some even offer different parts with different balancing based on the year of the engine. What are my options? Something like: 1. Look for codes/numbers that spec my engine so I can find exact match parts? But I understand these may still not be balanced right and should be taken to a machine shop to be checked for proper balance? Or are spec matched parts good enough for a low rpm application without additional balancing? 2. If newly bought parts need to be match balanced anyway, can I save some coin and just take the flywheel and balancer off my wore out 304 along with the 360 crank to a machine shop and have all match balanced? 3. Sell 360 and parts and use the money to start a Chevy 350 swap? I've had this engine for a few years and all the lack of balancer and flywheel has kept it on the stand all bagged up. I'd like to get it going if possible. Thanks for all info and help, -jim

jeepsr4ever

Check ebay for 360 balancer (non professional products...no 80101) and flywheel or flexplate.

tufcj

360s are all the same from 1972-end of production (1991?, the crank is different 71 and prior). AMCs are externally balanced, you MUST use a 360 balancer and 360 flywheel/flexplate.

As long as you're using factory pistons and rods, then stock replacement pieces will work, and balance will be acceptable. If you have aftermarket pistons, then the weight may be different from the factory piston and you should have the whole assembly balanced. Balancing will also affect the longevity of the engine, particularly the main and rod bearings. A balanced assembly spins smoother, so it will last longer. If you have it balanced, the machine shop will need the crank, flywheel, balancer, rods/pistons, and at least one set of rings and rod bearings. They make all the piston/rod assemblies match the lightest one, then they take the weight of a piston/rod/ring/bearing assembly and put "bob weights" on each rod journal and spin the crank with the flywheel/balancer attached to simulate a running engine. They then add or remove weight from the flywheel and balancer so the whole assembly spins smoothly.

The 304 balancer and flywheel/flexplate would take considerable modification to balance to a 360, because the 360 pistons are bigger, and therefore heavier.

For a factory damper: www.damperdoctor.com
Flywheel: http://www.omix-ada.com/jeep-parts/replacement/transmission-parts/manual/jeep-clutch-flywheel-parts/jeep-flywheel/flywheel-72-86-jeep-cj-models.html

I think MC here at Bulltear is an Omix-Ada distributor. You might PM him and see if you can get a better price.

Bob
tufcj