Balancing

[paul_f]

On another forum someone is trying to sell an engine with this spec

as41 case clearanced and welded in void where it breaks.
cb 78.4 4340 crank
cb unitech rods,
mahle forged b&p,
cb cnc ported heads  42/37,
 fk8 cam,
cb straight cut gears,
1.4 rockers,
bosch 009
cr is 7.85;1 so should be a lazy engine really ideal for a bus

When he was asked if it was balanced he said this

Balancing is pointless on components that are already balanced as without plugging oilways and inserting exact amount of oil that will be there when in operation and making your friction plate stop in same place every time it will never be perfect and all components are pretty good from factory .So no it has not been balanced. Mahle pistons etc and rods are already balanced to within a gram from factory, the rods and pistons are matched to give exact lengths though

What do other people think of his opinion?

[leec]

I think you already know the answer, sounds like it's just been assembled and not built. Would avoid unless your buying it as parts to rebuild yourself.

Lee

[paul_f]

It isn't for me - I don’t like low CR engines

I just had not heard this viewpoint before- but I know how much balancing my “balanced” kennedy clutch needed

[dyno don]

MY 2 cents worth...  The basic components look good but to take advantage of the package it would need more compression with at least 8:5/8:7 and better at 9:1 or more, although it will be just fine as is just not as efficient with that k8 and larger flowing heads although you could keep the torque values up with perhaps a 1 1/2 exhaust. The statment about matching ??...   There are many engine builders that dont balance  as they assume all the parts purchased are of a good quality and dont want extra down time if they have others waiting for repairs or rebuilds.  An engine will usually have no adverse effect  with not being balanced other than not being as smooth to operate and drive. I have seen many discrepancies over the many years from various parts sources but unless your building something that is going to be stressed(high rpm or heavy loads) then balancing from the 'box' will usually do well. I "prefer" to have all MY components balanced but have done several projects without as well with good results. Balancing will ensure a smoother running and overall performing engine but most anything with normal stress loads as in a stock application usually will never see the advantages of balancing unless the components are beyond the norm. Hope this sheds some more light onto your decision.

[kaferdave]

Somewhere, I have an old print photo of an engine I tore down...one side was 90.5's and the other side was 92's....The main bearing numbers had actually imprinted themselves on the main saddle in the case.
That was extreme, to be sure, but I would personally spend the extra $$ to get all rotating parts balanced, (and the pistons, as well....one gram ain't much, until you multiply it by 6,500-7,000 rpm)

[dyno don]

   Thats funny and reminds of when I use to ride in my friends( Souped up) 68 in 1970 with a holley 3oo bug spray that his friend built and he use to wonder why it heated up more on one side as opposed to the other until we eventually tore down and found in fact one side with the 90.5's and 92's on the other. Hope life is treating you well these days..?  Dyno

[richie]

On another forum someone is trying to sell an engine with this spec

as41 case clearanced and welded in void where it breaks.
cb 78.4 4340 crank
cb unitech rods,
mahle forged b&p,
cb cnc ported heads  42/37,
 fk8 cam,
cb straight cut gears,
1.4 rockers,
bosch 009
cr is 7.85;1 so should be a lazy engine really ideal for a bus

When he was asked if it was balanced he said this

Balancing is pointless on components that are already balanced as without plugging oilways and inserting exact amount of oil that will be there when in operation and making your friction plate stop in same place every time it will never be perfect and all components are pretty good from factory .So no it has not been balanced. Mahle pistons etc and rods are already balanced to within a gram from factory, the rods and pistons are matched to give exact lengths though

What do other people think of his opinion?

I have seen mahles as much as 10grams out from lightest to heaviest,and I have never had a set of rods that didnt need some material taken off to make them within a gram,as you pointed out kennedy pressure plates always eem to need doing.


That sounds like a pitch fom a truely dishonest sales person or someone who is not educated to the need to balance everything together

cheers richie 

[dyno don]

  Ritchie...  X2   

[paul_f]

Cheers for that, interesting to here the difference in the weight of the mahles!

A friend used some of the chinese 1600 b&p for a stock rebuild and they weighed within 1g of each other which I was surprised with.

I wasn't going to buy it, I just wondered what other people have found when having similar parts balanced.

My kennedy clutch not only needed several drillings made to it but it was also loose in the flywheel recess. The balancers did something to it to make it fit tightly as it should -  I think he said he swaged it

[kaferdave]

   Thats funny and reminds of when I use to ride in my friends( Souped up) 68 in 1970 with a holley 3oo bug spray that his friend built and he use to wonder why it heated up more on one side as opposed to the other until we eventually tore down and found in fact one side with the 90.5's and 92's on the other. Hope life is treating you well these days..?  Dyno

Hiya Dyno, Life is really good, Salmon fishing is off the hook right now, I may have to buy another freezer, headed for Bonneville next week to scratch one more thing off the Kaferdave Bucket List

[andy198712]

having weighed both the unitechs and Mahle pistons.... 1 gram is rubbish.... i forget the exact numbers off the top of my head but about 6 grams springs to mind? just in the set i have.

sounds a bit slapped together and with the low comp i would have though it would run hot with that setup no?

how much is it?

[paul_f]

£3000

[Jon]

Interesting point about the oil, does anyone have some thoughts on that?

[dyno don]

 Oil becomes a constant integral under pressure and doesnt inhibit or effect roating mass so I say" Poo Poo" on that topic.