Engine build Q

[thebrookster]

willows40 wrote:

Now I'm not a mechanic and apart from the basics don't know much about engines, but why are people saying about balancing the bottom end.
I know on a 'race' engine and the higher revs it's important, but why on a road car?
Is it really worth the extra money when the triumph engine is smooth as is, does it make it quicker, if so how much. Will it last longer? Etc. what are the benefits?

Cheers Andy

As I mentioned in a previous post, it the engine is going to remain relatively standard, and it was running fine before then there is no reason to balance the bottom end. As you correctly say, the engine is already pretty smooth to start of with, and as a road engine this is acceptable.

However, to counteract this, all these engines are getting older, and therefore any approach that will reduce the amount of stress put on the engine can be seen as good. Start increasing the power output as well and this becomes more important. So yeah, mostly about increasing longevity of the engine, and partially about negating additional stresses modifications may make, or at least that is how I look at it!

Cheers,

Phil

[junkuser]

I am in Ted's camp regarding doing repairs oneself.

After working in a fairly large motor mechanics shop as a teenager and seeing what went on, reenforced by also seeing a new Ford being returned to a relation after its first service at Sydney's main Ford dealer with no oil in the sump (not even the plug) with the expected results, I decided not to let anyone touch any car I may ever own.
Figured if I caused a problem, that was my fault, but can be very frustrating trying to get a fault rectified by someone else if they have caused the problem.

I get no satisfaction from doing standard mechanical repairs, replacing failed parts with bits of the same design, and have always had skin problems with oils, but I still believe I made the correct decision.  
(Attempting to improve the design of parts and making them is a different matter. Can be very satisfying.)

Have never regretted this decision having seen so many more problems caused by people in business who purport to be competent over the years since then.

[willows40]

1526

As a result nowadays to be honest I would have great difficulty trusting anyone to do it for me, though I am very happy to work with someone who is knowledgeable as I have with Gordon (Townley) with

Andy I agree that balancing is not necessarily a prime requirement especially with the six cylinder engine with its inherent balance.  However when highly respected people in the Triumph world with considerable experience of rebuilding engines recommend it because they consider Factory balancing to be a bit marginal who am I to doubt them.
If I was building a bog standard unstressed everyday engine would I do it - probably not.  However if I was building an engine where I would be pushing its performance even a little I [u wrote:

would [/u] do it.  And with the Mk1 PI engine I would do it as a matter of course simply to rule out a possible source of future failure - finding a long back cross drilled crank is bl**dy hard work  :-/

MUT

Hi Ted
I'm not criticising any body for doing it, just want to know the benefits and what difference it makes in a road car.
Does having it done really make enough difference for what it costs or are you better spending the money on something else

Cheers Andy

[piman]

Hello Andy,

it probably is difficult to quantify, especially in my case as I hadn't run the engine before it was balanced. I did it so as to get the best engine I could while it was apart, and it's not that expensive. The six is inherently in balance but the better it's balance is the smoother it should be. While very marginal a well balanced engine will give more power than an equivalent specified 'standard balanced engine' potentially?

I don't know current prices but if you are contemplating it the thing to do is to find out. If you are having a full bore/crank grind done it's probably not a significant cost on top of that I would guess?

Alec

[TedTaylor]

As Alec says it is hard to quantify and would really come down to planned usage of the engine and hoped for longevity.  

As I said, bog standard engine with no stress above normal usage I would probably not consider the effort and cost justified.
However if there was anything special about the engine (such as Mk1 PI) or it was planned to do anything which can put the engine under stress and push it to its rev limit then while the engine is apart it might as well be done.

And knowing Dave I bet he will hooligan his motor at any opportunity (whistle)

MUT

[JimEB]

Is there any other way to drive a Big Six other than in a distinctly spirited fashion?

;D

[Davemate]

1526 wrote:

knowing Dave I bet he will hooligan his motor at any opportunity (whistle)

MUT

😳😃😊😉

[Nick Moore]

An apocryphal tale: a friend had his 2500TC engine rebuilt, and had the rotating assemblies and pistons/rods balanced. It had always been a smooth engine anyway, but afterwards it felt like a turbine. Without overdrive it sat at about 4000rpm on the open road, completely vibration-free. It could as easily have been an electric motor driving the car.

He fitted an overdrive soon afterwards, which just means it's even faster.