Inliners International Forums General Discussion Engines Should I balance my motor?

I built my 235 with a stock crank, rods, and harmonic balencer. I am going to be pulling it out to fix some oil leaks, and was wondering if I should take it apart and have the guts balanced? As mentioned in a different post, my flywheel does not have the "X", but the pressure plate does. I also used the old harmonic balancer. The motor ran great, but I always strive for improvement. Should I weigh all the rods, and pistons and get them all equal? Is it all worth it?

i guess if it is apart anyway, why not rough balance the rods and pistons. it can't hurt. crank, flywheel have to go to a shop. tom

I thought it was worth every penny I spent on balancing my 235. Really smoothed it out. I had stock crank, rods etc too. The only thing I ditched is the stock balancer because I hopped it up.

Dear Dan;

It's only needed if (that word again) you plan to operate it above 4,500 RPM on a regular basis.

Otherwise; save your money.

Good luck.

even at 2000 rpm, a 1 oz weight will produce a big amount of vibration, especially when located at the 4" mark from center of crank. my 2 cents , balance it. tom

Since you already done the rebuilt, it's up to you and your pocket book and time frame.

For a street engine, you could leave it alone without balancing.

I have a 261 rebuilt from scratch - mostly stock - starting this month.
It will never go above 3000rpm but DEFINETLY have the crank balanced - no question!
The cost for that procedure is rather small compared to all the other expenses when rebuilding from scratch.

I've just finished the first 300 miles since my rebuild on my 60-235. My engine builder went out of his way to convince me that I WOULD see/feel the benefit of a dynamic balance of all the rotating assembly. Without question, it's the best money I spent on the engine. Granted it's a must on a high revving engine, but I for one, could not believe the difference it made from idle and up through the power band. It is SMOOTH...

You're probably only going to rebuild once in a lifetime with normal driving, and getting it right is a cheap price to pay when each time you crank it up you feel the difference.

Dave

What kind of harmonic balancers are used for this motor? What do you guys have experiance with? One of my friends just bought a fluid balancer, what is that, and would it be good?

Hey, we are developing a modern harmonic balancer right now for the 235/261 and the gmc's. this should solve a lot of the balance problems inherent with these long cranks. email me if you want the details

I used a modified 2 groove machined 250cid H/B from Buffalo Enterprises. Had it balanced down to .3 gram. All said and done, it was a bit pricy but the end result is outstanding. Running the A/C compressor directly off the front groove on drivers side with the alt/water pump on the passengers side. Works like a charm. One belt only over the adaptor plate mounted early water pump. Can run one other accessary off the a/c compressor second groove. Smooth as goose grease!!!

Dave

BTW....drilling and tapping the crank is also a good idea while you've got it out. Makes H/B installation easier....no BFH involved.

Geez, seems like you had a lot of modifications (read: cost) for your balancer. My balancer experience sounds the same as yours. I think we might be on to an easier, better alternative to balance these wobbly cranks and save some money to boot. No kidding on the drilling and tapping the crank as an alternative the the bfh...

i was planing on drilling and tapping the crank for sure. Thanks for all the info guys!!

My builder has a great reputation and is well known for his outstanding engines. He and the machine shop he uses absolutely insist on balancing. Not only the crank assembly, but the rods and pistons as well. Why go thru all the work and time of building a motor and not spend a few extra bucks to make sure it will be smooth? I'm not a professional mechanic, but I've never agreed with the "good enough" attitude. If one is looking to save money and/or just wants something to drive across the field or haul rocks or something like that, then they should just toss in any old motor that runs.