Balancing a Flathead

[JAKEFORD]

Can anyone explain what is involved in balancing the flathead V8.

Is there any techniques that could be applied if assembling an engine at home or is specialized equipment involved.

Also if one was to carefully weigh each reciprocating component and equalize their weights before assembly. would the engine be "balanced" or at least and improvement be noted.

Thanks

[JWL]

Yes, special equipment is needed.

Whether or not making all components alike would improve the balance of a specific crankshaft is a question mark.

The rods need to be balanced such that all the small ends and all the big ends weights are identical. Not just the overall weight. However, if you have a scale set which measures in grams and can properly "balance" the pistons, pins, and each end of the rods you will be ahead of the game when you take all your stuff to the machine shop to be dynamically balanced. Should save you some money.

[my4dv8]

For the sake of accuracy , kitchen scales won't cut it. It's a specialised job knowing what to remove or add .if you feel you have accurate gram scales you could do the pistons and each end of the rods.
You will still need to take your parts to preferably a shop that specialises in balancing . It will mean crank , a clutch cover, flywheel etc to get it all balanced dynamically , ie rotating.

[Bored&Stroked]

Things like the pistons are relatively easy - if you have a good scale (that goes down to 1/10 of a gram) and also know WHERE to remove the weight.

The rods are a lot more difficult in that each end has to be weighed and the 'fulcrum' point of where you 'hang' the other end (the one not on the scale) has to be steady, exact and not cause any frictional binding (or the weights recorded on the scale of the other end will not be correct). Also, the correct way to remove weight on the big-end of a flathead rod really requires that it is done in a lathe - you can't just grind off the bottom ribs on the rod cap (like a lot of folks do) - as these caps do not have balance pads incorporated (which is how most modern rods are). In my opinion, unless you already have a precision scale, know what goes into the balancing process (the static side of it), you're probably not going to save any real money and may risk damaging your parts - or making the shop that completes the job actually take more time. I'd just pay a high-quality flathead building shop to do the work. With that said, I make sure every flathead I build is balanced - just makes for really smooth running engines.

Here is a link to a thread I created on the HAMB - on 'Page 6' you'll see some posts I made about balancing rods, the fixture I made, the challenges, etc..

http://www.jalopyjournal.com/forum/t....862832/page-6

[GOSFAST]

Originally Posted by JAKEFORD

Can anyone explain what is involved in balancing the flathead V8.

Is there any techniques that could be applied if assembling an engine at home or is specialized equipment involved.

Also if one was to carefully weigh each reciprocating component and equalize their weights before assembly. would the engine be "balanced" or at least and improvement be noted.

Thanks

Hi Jake, it isn't necessary to chase every last gram in a set of rods or pistons to get them exactly even, it will have no overall adverse affect in the end.

If your pieces are within a few grams of each other you will be fine. In other words if you have a 5 gram (nominal) difference between them it won't matter. I would not try to get the OEM rods "perfect" gram-wise, you may cause more issues going this route with these particular forgings!

The final amount of the assembled bobweight is important however when balancing the crank. This number is comprised from all the component weights. This number also tells the operator what the crank requires to get it dialed-in better.

Thanks, Gary in N.Y.

P.S. It would really be a huge benefit to know exactly what pieces you are using?? Makes it easier to nail an answer down more accurately. Below shows a rod being weighed on our scale. The scale is a "Shadow-graph", strictly for balancing these type pieces. We run 2 balancers during the work week, one is a newer style CWT, the other is an older Stewart-Warner, both are extremely accurate! The CWT is much faster to use.

[Andy]

Sponsored Links (Register now to hide all advertisements)

I believe and agree with everything posted above.
Here are my thoughts after having a bunch of parts ruined by unqualified engine balancers.
I would not rush to balance a flathead crank. Henry built quality stuff anf knew what he was doing. A stock flathead runs extreamy smooth. The pistons can be checked and evened up at home. Just get them the same.
I had hell with the rods. The first machine shop desided one rod was bad and replaced it. It was lighter than the other 7. They ended up cutting and recutting to get them to match and turned the whole set to scrap. The next one was near as bad and wanted to grind one to the point of scrap again. I finally got a set done somewhere else. There is not much meat on a flathead rod than can be removed easily or correctly.
Here is whay I have come to believe. As the rods were forged, there was differences in the weights. Ford sorted the rods as to weight so less material would be removed in balancing. Loose rods in a bin are balanced but not to each other. A set of rods should be kept together and if one has to be replaced, a rod of the same weight should be selected.
I think there were maybe two or more standard weights for Ford rods. I know I have found them to vary a lot but not rods that have stayed together.
So my conclusion. The engines don't turn 8K so a stock crank is OK in balance. Get the pistons the same weight. Make sure the rods weigh the some.
Other have 100's of times my experience but mine was expensive and I just wanted to share my conclusions. Thanks

[big job]

All I can say, when new they were extremely smooth so quiet we were always
replacing starter drives cause people though it wasn't running and pushed the button.
(I have to look at my oil pressure at a stop cause I can't hear or feel mine running).
Most issues were at some point the clutch, plate and disk replacement out of balance.
When we do an engine the whole flywheel clutch is balanced and marked for the
install. Then the old saying "anything that goes around has a moment " like going
in and out of phase. Phasing is touchy so much that late Neons has a balancer driven
by a chain- Detroit Diesel a balance shaft. I was given a ride other day in a mint 41 Chev just a 40 oh my. No thanks. At 40 in second all I hear is the fan V8. ther ya go