Stock or light flywheel?

[NigelDenham]

Hi, second thread of the night! I’ve just pulled my engine to deal with a leaky bell housing. The culprit is the gearbox input seal not the crank…..anyway, according to the build file by Kingfisher Kustoms my motor apparently has a chromoly counterbalanced crank and lightweight chromoly flywheel. Std cam, it had a sorry looking single Weber 44idf, and was running like a pig When I got it. I have fitted a rebuilt solex 34 pict-3, so now pretty much a stock motor. I don’t like the idea of a light flywheel on a bus, and you do have to be careful of stalling sometimes, so have looked at a VW (brazil) stock flywheel from VW heritage. However they list the weight as 7.15kg, and the light one I have is listed as 6kg….. doesn’t seem much difference to me.
Any thoughts or personal experience anyone?

 

[sparkywig]

Off the top of my head stock flywheels are around 17lb in old money, with lightened ones around 12lb.
That's an extra 2 1/2 bags of sugar spinning on the end of the crank.
Apparently stock flywheels are better in a bus, but I've run lightened flywheels on stroker engines for the last 12 years or so with no ill effect.
Lightened flywheels allow the engine to gain and lose revs quicker, but can idle rougher and are easier to stall than a stock weight flywheel.

 

[NigelDenham]

I’m assuming the VW brasil one would be cast rather than forged steel?

 

[sparkywig]

I think they are, that's what I've weighed in the past.

 

[NigelDenham]

Off the top of my head stock flywheels are around 17lb in old money, with lightened ones around 12lb.
That's an extra 2 1/2 bags of sugar spinning on the end of the crank.
Apparently stock flywheels are better in a bus, but I've run lightened flywheels on stroker engines for the last 12 years or so with no ill effect.
Lightened flywheels allow the engine to gain and lose revs quicker, but can idle rougher and are easier to stall than a stock weight

Just done the conversion, the vw Brasil one is 16lb 1 oz whilst the lightened one I have is just under 13 1/2 lb
i wondered if the old German flywheels were heavier?

 

[static]

Just done the conversion, the vw Brasil one is 16lb 1 oz whilst the lightened one I have is just under 13 1/2 lb

Didn’t know that.
Thanks for the enlightenment.

 

[K@rlos]

On a street driven engine, especially a stock bus engine with little torque a heavy flywheel will make for a nicer, and smoother drive. I’ve driven many buses with performance engines and a the heavier is always a superior drive. The 2276 in my bus has a full weight flywheel with heavy Gene Berg equaliser pulley and that still screams like a banshee

Lightened flywheels are the most beneficial on track & rally cars as it allows the engine gain and loose rpm quickly when on and off the throttle alot from coming in & out of corners etc. Many drag cars actually run a faster time with a heavy flywheel as it gives more momentum/inertia and a harder launch, my friends turbo notchback improved the 60ft time considerably by going to a heavy flywheel.

 

[NigelDenham]

On a street driven engine, especially a stock bus engine with little torque a heavy flywheel will make for a nicer, and smoother drive. I’ve driven many buses with performance engines and a the heavier is always a superior drive. The 2276 in my bus has a full weight flywheel with heavy Gene Berg equaliser pulley and that still screams like a banshee

Lightened flywheels are the most beneficial on track & rally cars as it allows the engine gain and loose rpm quickly when on and off the throttle alot from coming in & out of corners etc. Many drag cars actually run a faster time with a heavy flywheel as it gives more momentum/inertia and a harder launch, my friends turbo notchback improved the 60ft time considerably by going to a heavy flywheel.

thanks for the input. I think it confirms my view. I can’t see the point on an otherwise stock engine, it’s not like they produce more power. I think the company who built it do buggy’s and probably just put them in all their motors. I did look at those Equaliser pulleys as an alternative to swapping out my flywheel. Isn’t the idea that you then have weight at both ends of the crank instead of one?

 

[static]

Me thinks that if the teams of German engineers thought that a lightened flywheel was a good idea for our buses then they would have specified them.

One thing that they did specify is a specific distributor: a 211 905 205Q, when married to a 34PICT3, is the correct answer. While almost all Bosch dizzys will work, the 211 905 205Q has the low-end grunt that our buses need. (As explained by mechanics much smarter than me).

Once I installed one in my ‘71, my bus ran substantially better.

 

[K@rlos]

thanks for the input. I think it confirms my view. I can’t see the point on an otherwise stock engine, it’s not like they produce more power. I think the company who built it do buggy’s and probably just put them in all their motors. I did look at those Equaliser pulleys as an alternative to swapping out my flywheel. Isn’t the idea that you then have weight at both ends of the crank instead of one?

An equaliser pulley is only really worth getting on an engine that sees high rpm as they are designed to absorb the harmonics produced at such engine speeds. For a stock motor I’d personally get a heavy flywheel and a good stock pulley.

 

[NigelDenham]

Me thinks that if the teams of German engineers thought that a lightened flywheel was a good idea for our buses then they would have specified them.

One thing that they did specify is a specific distributor: a 211 905 205Q, when married to a 34PICT3, is the correct answer. While almost all Bosch dizzys will work, the 211 905 205Q has the low-end grunt that our buses need. (As explained by mechanics much smarter than me).

Once I installed one in my ‘71, my bus ran substantially better.

I’ve got a 905 205L for mine, supposed to be one of the recommended dizzys for a bus. Can’t say I’ve noticed much difference to the pertronix I have in use, but it is running points.

 

[NigelDenham]

An equaliser pulley is only really worth getting on an engine that sees high rpm as they are designed to absorb the harmonics produced at such engine speeds. For a stock motor I’d personally get a heavy flywheel and a good stock pulley.

Thanks for the help. Only issue is the crank/flywheel fitted is 8 dowel, so best practise I suppose would be to have any replacement drilled. I wonder though if I could fit the 4 dowel flywheel with maybe shortened dowels supporting the “empty” holes?

 

[K@rlos]

Stateside tuning sell full weight German flywheels drilled for 8 dowel and would modify a 4 dowel for you

 

[NigelDenham]

Stateside tuning sell full weight German flywheels drilled for 8 dowel and would modify a 4 dowel for you

Thank you so much, just checked out their site. Great help