188 replies to this topic

[rodomo]

They are noisy.................................besides that?.............................they're O.K IMHO

[EunUCh]

And they do this to camshafts

[EunUCh]

Blower had crossed my mind,but because these things vibrate like all fuk it would

seem that they have some sort of inherant balance problem that needs sorting out first.

Is there anyone on this forum that has a starfire powered Torana in which the

engine is still from factory and if they are game could they tell us if they vibrated from

factory.

[tor308]

i dont know alot about them my self but i have noticed they dont run a harmonic balancer from factory not to sure why maybe cost?

also i have read that you are not meant to use the alloy cam gear on the starfire either again not sure why just read it in the JP gears instructions.

[EunUCh]

Yep,I read that about the alloy gears as well,but I also read not to use alloy gear without balancer.But

I dont remember where I read it.

Fitted balancer and drove water pump/alt.from original s/fire pulley on front of balancer hub when it had fibre gear,made no difference to vibration problem,same deal with alloy gear.

They seem to have some other balance problem that needs attention,the way I see it is why should a s/fire have

such a bad vibration problem when there were other 1.9's out there that didnt seem to have it.

They are not a very popular chioce of engine but with the stuffing around we have done over the last 10 years they do seem

to respond to certain mods,its just the vibration problem that knocks a bit out of them.

[EunUCh]

Yeah Bomber, got a pick of cranks but the ones we have used were balanced again

before we fitted them and the little shits of things still shake.

They definatly have a problem.Maybe just forget the whole exercise and write it off 

as a nightmare.

[EunUCh]

Havn't had any cracked blocks,they shake almost everything thing else off that is hanging off

the block.I wont list the stuff and things that come loose or break.

It is starting to beat me,there is only a couple of other things to check out but it involves

some brain fuk type mathematics which I am not in the mood for right now.

Speaking of the flat crank,that is an area that we have not looked at properly yet,so here goes.

I have been trying to find out as much as possible about crank balancing,seems all I can find

is on v8's and singles.So if we look at a single cylinder engine the general rule for most balancing

acts seems to be  based around the 50% balance factor,which basically deals with a % of  reciprocating weight and 100% of rotating weight(bigend of conrod & bearings),(lets not get in to moment of mass) and ignores "hybrid" weight,lets not go there either.

So if we do some numbers on our theoretical single and end up with a number,theoreticaly thats the amount

of counter weight we need on the crank somwhere to balance things out pretty good.

Lo and behold they use the 50% factor when balancing v8's as well.

So now we look at a 4 cylinder flat crank,1&4 and 2&3 weights are 180 out of phase,all good,

if the designers got the numbers spot on in counter weight phasing and got

all the weights the same that crank should just need the journals etc. machining and

you could fit that crank in a balance machine and it would be perfectly balanced.

I have had a couple rebalanced and they came back with about a 3/8 size hole 1/16 deep in one place

that it makes one wonder why you would pay for such an act.

Now we have a perfectly balanced crankshaft,it spins nice,it is smooth,all good on the balance machine. 

Now this is what i am trying to get my head around,if we then take our beutifully balanced crank shaft and

bolt some rods etc to it,is our crankshaft still balanced?,keep in mind the balance factor!...

[Uncle Chop Chop]

Is there anyone on this forum that has a starfire powered Torana in which the
engine is still from factory and if they are game could they tell us if they vibrated from
factory.

I sort of remember driving several (then) new VC/VH Commodores with the 4 banger. Please remember that this was 30 years ago and I never owned one personally. But from memory they weren't real smooth.

[rodomo]

The old B series BMC engines

I had a 1956 Morris Minor with the 803 engine that broke a crank at idle.

Both of my daughters had Commodores with starfires and neither of them were super smooth, quiet engines. One VC and the other VH.

[hanra]

^^ that might have been an A series?

Edited by hanra, 13 April 2013 - 08:40 AM.

[EunUCh]

Ok,so now we know that they were not real flash from the factory,thats good to know because it virtually eliminates 

what we have done as causing the problem although we may have amplified it a bit.

The shaking is probably there all the time but is most noticeable  in "bands" at different rpm points,the point where

it is "nice" is at 3000 but ironically that was 100k in overdrive when the cam decided to get intimate with some

bits lower down the food chain.

I see what you mean oldjohnno,and even though multi cylinder engines will behave differently than a single what I was trying to illustrate and

try to understand is that if we take a single pot engine apart and remove the conrod from the crank and then sit the crank on knife edges

will that crank  fall to the heaviest point and stay there? If it does then we would have to say that the crankshaft or rather the counter weight or some other part is the imbalance.

If we then "balance" out the difference so that the crank when on knife edges does not fall to a heavy point could we say that it is then "balanced"?

I would say yes,but, if we now go and connect a bob weight of a calculated weight to mimik the big end and a portion of reciprocating weight

will that crank and the weight behave as it should when it is rotating?.i would say no but thats just my opinion.

I could be getting way out of touch with reality and basic understanding here but should not the bit that spins be "out of balance"

untill the reciprocating and rotating bits are attached to bring it back to "some balance".I dont know,maybe i need a holiday or something.

[UCgazman]

This reminds me of when we bought the UC years ago, we got it cheap because the starfire wouldn't run properly. I looked over the motor and found both manifolds had shaken loose...

[EunUCh]

^^ Yes I understand that it is always a compromise and that there is no such thing as a perfectly balanced engine,some of them even take rings into consideration.It is impossible not only due to mechanical factors but also because of the ever changing forces of induction,exhaust,combustion pressures,resonance etc.but the starfire must have a compromise factor way outside the window of tolerable compromise and thats what gave them a really bad name.

 

Personally I think the horrible little things do have potential to be a resonable little engine that if sorted would perform quite well for what they are.

I did read something about these engines being used in Gemini rally or something but you cant always beleive what the net says,and if they did use them they must have "fixed" the problem to a good degree or else in race conditions it is unlikley they would last too long.

 

Looks like I dont get out doing some numbers and possibly even some band saw work.

 

Will post some pics when I have finished ripping out hair

 

 

 

 

 

 

[EunUCh]

^^ Iam getting some ideas now.....see how we go.

I was leaning toward underbalance as well but will do some proofing as to get an idea