VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Engine Balance Question

Are 216 and 235 engines internally balanced or balanced by the flywheel?
The point of the question is, if a flywheel from a 216 engine is used on a 235 engine, would it necessarily put the 235 engine out of balance?


Bill

They are not balanced by the flywheel

Hi Bill,

Please follow up your research by using the SEARCH process on our chat site. There is a lot to investigate. Here is some discussion in an old post for you to reflect on: vccachat.org/ubbthreads.php/ubb/showflat/Number/374723/Searchpage/2/Main/58028/Words/%2Bharmonic+%2Bbalance/Search/true/re-1941-chev-special-deluxe-engine-vibration.html#Post374723

Good luck, Mike

P.S. Sorry the link seems to not want to insert itself correctly. Will try to repost it later!!!

Though the flywheel may not be the primary balancing part it can have an influence if it is out of rotational balance. Most have small holes drilled to balance them.

Wat he is reffering to is was the flywheel purposely unbalanced to correct the un natrual balance of an engine.

The only example of this with a Chevrolet engine is the 1970 and up small block 400 engine. Both the flywheel (flex plate had large weights welded on) and harmonic balancer were made grossly out of balance to correct the imbalance of the crankshaft.

Early engines were balanced by weighing and selecting equal weight parts such as the connecting rods and pistons. Starting with the 1955 265 the engine was spun and balanced after assembly and crankshaft counter weights drilled to correct balance.

Bill

Ran the flywheel from my 216 of a '54 235 powerglide while my 216 was being rebuilt (10,000 miles). Did not have any problems. Had to time the 235 by ear as the "ball" on the 216 flywheel is in a slightly different position.

Thank you to all who have provided input to clarify my concern. For the record, quite often I'll try to search past threads for information, but quite honestly I don't seem to do so well in finding what I'm looking for. That coupled with the fact I know someone out there has the answer to my exact question, often leads me to just asking the question.
Thank you again for the input.

Bill

I'm with you bill ! 100%

Bill,

This article explains how engines are balanced:

https://www.enginebuildermag.com/2014/03/weighing-balancing-work/

As the article describes piston and rod weights are equalized by weighing them all then machining the heavier ones to match the weight of the lightest one. Also described in the article is how crankshafts balancing can involve drilling the counterweights to lighten them or welding or adding "heavy metal" to increase counterweight weight.

Doing this:

"Starting with the 1955 265 the engine was spun and balanced after assembly and crankshaft counter weights drilled to correct balance." described above by Gene would require either:

1. Doing the balancing work with the rotating assembly (rings, pistons, piston pins, piston pins retainers, bearing inserts and connecting rods) INSTALLED IN THE BLOCK as Gene describes would require that the rotating assembly be removed from the block after balancing to remove the debris created by machining related to the balancing and then reinstalling the rotating assembly.

or

2. Installing the rotating assembly in the block to spin it then removing the rotating assembly to balance it then reinstalling the rotating assembly,

It's hard to imagine either of those procedures being used when the simpler and quicker procedure described in the article is available.

What am I missing?

My personal experience with engine balancing comes from rebuilding the 360 cubic inch Chrysler LA engine in my 1971 Dodge van and from building from scratch a 350 cubic inch small block Chevy engine for my 1932 Ford roadster street rod. Both of those engines run without any perceptible vibration at any RPM. They both have the smoothness of electric motors. From that I conclude that a precision balance is worth the cost. Like cylinder honing with a torque plate it adds a little cost but makes a big difference in engine performance and longevity which matters as much in an antique vehicle engine that is not in a trailer queen as in a race engine.

Ray W

Ray, thank you for the link, very informative article.
Hopefully, I will not have any major balancing problems.
Thanks again,
Bill

"Ray, thank you for the link, very informative article."

You're very welcome Bill. Some of what I read on these forums by the "experts", like the story about balancing rotating assemblies in the block, makes me shake my head in disbelief. Another interesting topic is the concept of honing cylinder bores with a torque plate attached and the main cap bolts tight to create a perfectly round bore when the engine is assembled. Here's an article describing that:

http://www.gallowayengines.com.au/torque-plate-honing

That concept has been around for at least 35 years that I know of and probably a lot longer than that but many engine machine shops look at you like a deer in the lights when you ask them about it. Even on a street driven engine the benefit becomes really obvious when the engine accumulates a lot of miles but doesn't show any excessive oil consumption. The obvious reason is that the round piston rings didn't have to do the work of final shaping of bores made angular by head bolt distortion.

I think the few of us who are actually interested in this kind of stuff need our own forum. Antique vehicles that aren't trailer queens but are actually driven can benefit from the information that is constantly in the automotive trade and enthusiast publications. The topics are endless.

Ray W

Hey Ray,
Check out www.rlengines.com for some good info on engine balancing regarding internal and external balancing and centripetal force. Good reading for those that want to get deep into the technical aspect of it. Also lots of other deep reading on the internet while the Chat Site is more of a site for Chevy owners to share general knowledge of keeping their cars looking and driving in good condition.

Good morning Steve. Thank you for sending that link. It was an interesting read.

I’ve been interested in car related topics since I was a teenager in the 1950s and 60s. Back then our economy included a lot of manufacturing and men in the neighborhood had those manufacturing skills and were doing all kinds of car related stuff on restorations, street rods and even race cars. In fact there was a fabrication shop right across the street from my elementary school where Indy “roadsters” were built to run at the “brickyard”. So everything on a car or truck is interesting to me and I’ll try anything, learning new skills in the process. Most recently one of my neighbors who is a vintage race car fan took me to a vintage race event. There I was struck by the beauty of “engine turned” metal panels on those vintage race cars and set out to learn that metal texturing technique. It has no application on my restored ’36 Chevy pickup but the engine turned metal parts on my ’32 Ford roadster street rod are interesting “eye candy”.

Fast forward to the late 20th century or the 21st century and that’s all changed. The guys I meet in both restoration and street rod activities I’ve sampled are about as interested in the inner workings of their vehicles as they are in the inner workings of their kitchen stoves and refrigerators. Their fun is in taking a short “tour” (restoration speak) or "cruise" (street rod speak) to a restaurant. So those of us who like to tinker, learn new skills and fabricate have a hard time finding each other.

The one exception to that is the men and women who campaign land speed record vehicles on the dry lakes of the Southern California Mojave Desert and on the Bonneville salt flats in Utah. The movie The World's Fastest Indian is about that sport. Those creations are labors of love that are hand built in home garages and shops. Their owner/builder/drivers leave no stone unturned in looking for that last horsepower or that last (class legal) aerodynamic improvement to raise a class record by a MPH or two or even a fraction of a MPH. I have been disappointed in owning my ’36 Chevy pickup since 1965 and in being a VCCA member for over 40 years, finally quitting in 2009, to not be able to find that personal involvement and focus in any restorers I met.

A few days ago a guy who is an AACA member saw me and my wife with our ’36 PU at a local park munching on a picnic lunch and invited me to one of their meetings next week. Maybe there’ll be an old school do it yourselfer or two there. If anyone on this forum is interested in swapping information on old school home creations I'm all in.

Ray W

Thanks again to all who contributed information to my question. I'm especially pleased to see how it went further than a "yes or no" answer and generated additional in-depth resources. This is especially helpful to those of us who are mechanically and computer challenged.

Bill

The article on balancing is interesting as it pertains to the procedures that are used in the shop. Some of the stated theory however is wrong. Specifically, balancing a single cylinder engine by adding a counter weight to the crankshaft to counter the reciprocating forces will not work. It would merely create the equivalent imbalance on the axis ninety degrees to the piston movement.

So at least you should check these weights. Recently I found an engine for my 29. The fellow who had it was going to hot rod a 29 coupe. The story he got was that it had been rebuilt. When I looked at it there was A LOT of rust in the water jacket in the block. Turned out when I got the head off that it had all new pistons, rods and mains professionally rebabbited. After taking it apart I took it to a local shop I use. He touched up the cylinders, polished the crank, and checked for balance. Even though the rods were the same, the pistons and pins the same - between the high and low weights there was 45 grams. Almost 2 ounces. Now as you know these engines had their HP rated at 2900 rpms. Not very fast, but... He was able to swap things around with a change of piston to rod combination and get it down to 14 grams. Since it had never been started it was not going to make any difference where the pistons end up but the rods should have been fitted to each journal. There was really not any place he could have taken off any metal so it is what it is. I had him do the flywheel and pressure plate as well. He took 10 lbs off that combination.

Gene,
I thought the 454 Chevy big block was also externally balanced.

Mike

I think you are correct.

I will always reember the small block 400. When I was in the parts department a mechanic ordered a flex plate for a 350 with automatic trans. I gave him the flex plate and he came back in a short and said the engine vibrated so back it would hardly run. Then I asked him if he was sure it was a 350. He came back and said, no it is a 400. The correct 400 flex plate with the huge weights solved the problem.

Chevrolet's description as to how the engine is balanced in the all new 265 enine in 1955.

New technological and prosessing has been adopted to balance the engne. The crankshaft is partially balanced on a newly developed machine which has electronically controlled indicators. Final balance is acheieved after the engine is assembled. BEFORE THE OIL PAN IS INSTALLED, THE ENGINE IS PLACED ON ANOTHER NEWLY DEVELOPED MACHINE WHICH MOTORS THE ENGINE. THIS MACHINE INDICATES ANY OF THE OUT OF BALANCE OF THE COMPLETE ENGINE , STOPS THE ROTATION AT THE INDICATED OUT OF BALANCE, AND DRILLS THE FRONT AND REAR CRANKSHAFT COUNTERWEIGHTS THE AMOUNT REQUIRED.
THROUGH THIS NEW EQUIPMENT, NOT ONLY THE CRANKSHAFT, BUT ALL THE MOVING PARTS OF THE ENGINE AND CLUTCH ARE THUS BALANCED.

Not local machine shop would be equipped to do this.

Gene that is good info and makes perfect sense. For a similar reason on the heavy trucks wheels were balanced on the truck. This allows balancing of all the rotating components together at one time.

"This allows balancing of all the rotating components together at one time."

Steve,

What Gene describes omits some critical elements of balancing. First, true "balancing" begins with equalizing the weights of the unassembled pistons and rods by weighing them all then machining the heavy ones to the weight of the lightest. Then "bobweights" are attached to the crankshaft journals and it is spun in a fixture that detects vibrations from imbalance and pinpoints where counterbalance needs to be altered by adding or removing weight. Bear in mind that sometimes "balancing" requires adding weight to the crankshaft counterweights.

If the weight equalizing steps are omitted then the machine has to "average" the rod and piston inconsistencies. Also, any differences in bearing and/or piston/ring friction spinning the rotating and reciprocating assemblies in an assembled block will be misread by the balancing machine as imbalance and will affect the process according to what I've read about engine balancing.

I guess it could be said that some balancing improvement is better than none.

I've rebuilt a couple of engines that I first drove for a long time with the factory balance. Part of my rebuilds was a precision balance and the feel of the engines was totally different. When revved up a precisely balanced engine feels like an electric motor it is so smooth.

Ray W

Ray I agree that there are things that can be done to make the balancing process more accurate but the factory process that Gene describes is a production process and sometimes that means building to an "acceptable " level and not always the most accurate possible. Keep in mind the cost involved also influences the final process decision. The shop I referenced in an earlier post builds their race engines and others if desired to "blueprint" specs. Their machining detail process is actually more accurate than the factory process but the additional expense is not something I am willing to pay for the limited benefit it would give me for a low RPM seldom driven antique car. As long as I can get from point A to B in a normal manner I will be satisfied. If I were planning on entering the Great Race it would be a different story.

"Their machining detail process is actually more accurate than the factory process but the additional expense is not something I am willing to pay for the limited benefit it would give me for a low RPM seldom driven antique car."

Steve,

I totally agree with you. In assembling engines I try to pick the "low hanging fruit". For me that includes stuff like removing casting flaws and sharp angles that cause turbulent flow in cylinder head port "bowls", carefully adjusting bearing clearances and ring gaps, having new bores honed with a torque plate and (yes I admit it) having the rotating assembly balanced. Beyond that the point of diminishing returns is reached quickly.

On my restored '36 Chevy pickup all the money I did not spend at wood, body, paint, engine, transmission, differential, electric and upholstery shops because my wife and I are do-it-yourselfers easily covered the cost of precision engine machining.

To each his/her own, huh?

Ray W

I totally agree Ray.