smooth 65% balance factor and best sealer

My experiences with balancing with isolastic mounts.

This was using my own long rods and lightweight pistons which were not as light as the JS setup in my Commando racebike.

The least vibration felt with a standard iron barrel motor was at about 58% dry which would have been in the lower 50's wet.

When I went to an aluminum barrel the vibration in the bars increased so I raised the balance factor to around 62% dry which
made it better, then I went to 65% dry which made it worse again. I settled at 62% dry.

This has nothing to do with the balance factor needed in a solid mount frame which is determined by the frame dynamics. The only way I know to get that right is by trial and error. Jim

@john robert bould: I hope that my sarcasm was not lost in the following statement:

Dances with Shrapnel said:

And who is Phil Irving anyway?

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@comnoz: Thanks for the information - fits the math, fits the model and fits my understanding.

:lol:

This is Phil Irving :lol:

Dances , I know what you were saying, but for the record - Phil Irving was involved in designing the Vincent, and I believe also Velocettes. Later he worked for Repco developing the Repco Brabham engine which Jack Brabham used in Europe with great success. The motor was a n aluminium Chrysler V8 with a four valve per cylinder DOHC head. In later years he also developed a 4 valve head for the 6 cylinder Falcon. His book 'tuning for speed' is a must for anyone wanting to race a pre 65 motorcycle, and I've lost my copy. The book is correct and extensive in most of its technical detail It lists the cam timings of most of the early racers , describes how to balance a crank. It is an extrely useful read. Phil Irving was a rarity amongst motorcycle designers , he was a university degree qualified Automotive Engineer in the 1930s. He was an example of a sort of person who does not exist in Australia these days. That photo of him sitting on the VIncent makes me feel very sad.

The bike picture was a joint venture vincent/indian . not a welcome concept.

acotrel said:

Dances , I know what you were saying, but for the record - Phil Irving was involved in designing the Vincent, and I believe also Velocettes. Later he worked for Repco developing the Repco Brabham engine which Jack Brabham used in Europe with great success. The motor was a n aluminium Chrysler V8 with a four valve per cylinder DOHC head. In later years he also developed a 4 valve head for the 6 cylinder Falcon. His book 'tuning for speed' is a must for anyone wanting to race a pre 65 motorcycle, and I've lost my copy. The book is correct and extensive in most of its technical detail It lists the cam timings of most of the early racers , describes how to balance a crank. It is an extrely useful read. Phil Irving was a rarity amongst motorcycle designers , he was a university degree qualified Automotive Engineer in the 1930s. He was an example of a sort of person who does not exist in Australia these days. That photo of him sitting on the VIncent makes me feel very sad.

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The Indian Vincent was a good idea, however combining a top British motor with a poor American chassis was probably doomed to fail in the market place . It was sort of like fitting a Ducati Desmosedici motor into a Harley Vrod chassis. I believe that when Indian went bust, Vincent also collapsed as a result of their commitment to that project ? There have been a few examples of that sort of idiocy with the British. Like trying t o build Italian style motor scooters, also those stupid chopper style three cylinder triumphs with the exhausts all out one side. It was a matter trying to grab a bit of the market, but they didn't seem to realise that they were following, not leading.

acotrel said:

Dances , I know what you were saying, but for the record - Phil Irving was involved in designing the Vincent, and I believe also Velocettes. Later he worked for Repco developing the Repco Brabham engine which Jack Brabham used in Europe with great success. The motor was a n aluminium Chrysler V8 with a four valve per cylinder DOHC head. In later years he also developed a 4 valve head for the 6 cylinder Falcon. His book 'tuning for speed' is a must for anyone wanting to race a pre 65 motorcycle, and I've lost my copy. The book is correct and extensive in most of its technical detail It lists the cam timings of most of the early racers , describes how to balance a crank. It is an extrely useful read. Phil Irving was a rarity amongst motorcycle designers , he was a university degree qualified Automotive Engineer in the 1930s. He was an example of a sort of person who does not exist in Australia these days. That photo of him sitting on the VIncent makes me feel very sad.

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I share your pain as it seems there's a serious dearth of quality technical people worldwide.

As for Phil Irvings latest version (Sixth edition) of tuning for speed, http://www.Amazon.com lists four used copies; three of which are listed at $473.27 and one for $850 - yikes!!!!

acotrel said:

Dances , I know what you were saying, but for the record - Phil Irving was involved in designing the Vincent, and I believe also Velocettes. Later he worked for Repco developing the Repco Brabham engine which Jack Brabham used in Europe with great success. The motor was a n aluminium Chrysler V8 with a four valve per cylinder DOHC head. In later years he also developed a 4 valve head for the 6 cylinder Falcon. His book 'tuning for speed' is a must for anyone wanting to race a pre 65 motorcycle, and I've lost my copy. The book is correct and extensive in most of its technical detail It lists the cam timings of most of the early racers , describes how to balance a crank. It is an extrely useful read. Phil Irving was a rarity amongst motorcycle designers , he was a university degree qualified Automotive Engineer in the 1930s. He was an example of a sort of person who does not exist in Australia these days. That photo of him sitting on the VIncent makes me feel very sad.

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I dis-agree, Phil Irvings book is not only good for those wanting to race a pre 65 motorcycle as most of the principles still apply today. I have read and re-read his book many times over the years and it is still in with my main reference books. Jim

A now deceased friend of mine had a really bad claim to fame. He was at a race meeting at Phillip Island and loudly shit-canned Phil Irving. The jerk (oops!) didn't realise that Phil's widow was standing near-by and overheard him. Phil was interesting to talk to, I only had one conversation with him about 40 years ago, he was extremely switched on about bike stuff. I had his book last time I rebalanced my crankshaft, I don't know where it has gone, I searched for it a while back and couldn't find it. I don't want to pay nearly $500 for a new copy, however I believe it was updated in later versions.

@acotrel

For what it is worth, I found a downloadable fourth edition, third impression here:

http://tuningforspeed.com/files/Tuning_for_Speed.pdf

I suspect the lions share of the key information is there.


Below is a link to a seller of used books in the UK that lists the Sixth Edition for more sane prices:

http://www.abebooks.co.uk/book-search/title/tuning-for-speed/author/irving/sortby/3/page-1/

I have the 6th edition. I could probably be talked into scanning sections if you want. Jim

Hey JS, you've pointed out the added benefits of the reduced mass of the shorter pistons and the lower thrust angle from your long rods on the crank journals. This must reduce some whip on the crank and over all reduce vibrations too. Just wondering what would be the percentage that these factors contribute to the overall smoothness being reported here as balance factor?

I am fortunate to have the Sixth Edition of Tuning for Speed. I briefly compared the chapter titles and other than some fine nuances in the phrasing of the Chapters they are identical except the Sixth Edition includes chapters on "Supercharging and Specials" and "Sparking Plugs". So it looks like the online pdf version has the lions share of the pertinent information.

Thanks for the offer Jim. All good stuff.

Since Phil Irving was mentioned, here is a little bit on the Repco Brabham V8- I hope people won't mind the momentary diversion from balance factor.....

"He was never given much credit by Brabham for the brilliant design work he did on that engine. To put it in perspective, consider Henry Ford Jr.'s 1960s quest to win the world's most coveted Auto race trophy- the 24 hr Lemans.
It is to auto racing what the IOM TT is to us, the ultimate prize.
Ford first tried to make an outright purchase of Ferrari for a steal of a deal at the time, something like 15 million. Ferrari agreed, then changed his mind and reneged on the deal. So Ford spent many times this amount to wrestle the trophy from Ferrari, Porsche and the other established Leman winners. Some years Ford would enter 5 cars and none would finish, on fire, broken and failed. Eventually, after teaming with Carrol Shelby and spending many more millions on development, they got the job done in rather spectacular fashion.
Compare this to Irving's acheivment at Lemans. Vincent is long since bankrupt, Irving is back home designing tractor engines or what have you when Brabham asks Irving if he could design an V8 engine for an assault on the 24 hr race. Irving does so in his usual all out, hands on manner and the bloody thing wins the 24 hr Lemans first time out! Btw, the Repco V8 has the exact same inspection caps as my Vincent uses, minus the Vincent logo.

Very few people even know the story, hopefully a few more do now."

great Info, and refreshing. Testimony to PE ,an unassuming guy with a slide rule and pencil ..responcable for design's and inovations that made world records.

worntorn said:

Since Phil Irving was mentioned, here is a little bit on the Repco Brabham V8- Very few people even know the story, hopefully a few more do now."

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Well I didn't know that, thanks for posting it worntorn.

I used to work around the corner from the Repco factory where that motor was developed, and a friend used to work there . It was a pokey little joint in the Melbourne suburb of Footscray. I have another friend who bought a Repco Brabham V8 because he wanted to do 290 KPH at Phillip Island before he leaves this planet. They are a really exciting bit of gear, we still have about three of them in Victoria, and they often get shipped t o Europe for meetings such as the Goodwood Revival. I've been involved in running the historic car and bike meetings at Winton Raceway, and we always try to get those cars to come and race.

Yes, Irving had an amazing talent and was a very competent machinist as well. When the first Black Lightning was being created Irving could be found working till all hours in the Vincent Machine shop. He hand cut the first of the Black Lightning cam profiles, lightened the valve train parts, made new gears for the trans to create closer ratios and made a thousand other little changes to lighten the bike and pull more power from the engine.
Vincent had a lot of great ideas too, and those are also incorporated in the bikes. Vincent was also smart enough to know that Irving could do great things, that is why he hired him.

Glen

If the sludge trap runs half full plus oil in the journal cavities, [7 % of crank total reported] doesn't that put more mass opposite the piston mass than dry? Aren't extra bob weights put on opposite the piston mass to raise BF? How does the oil mass opposite pistons lower BF? What am I misunderstanding? Is the oil mass opposite the reciprocating mass?

hobot said:

If the sludge trap runs half full plus oil in the journal cavities, [7 % of crank total reported] doesn't that put more mass opposite the piston mass than dry? Aren't extra bob weights put on opposite the piston mass to raise BF? How does the oil mass opposite pistons lower BF? What am I misunderstanding? Is the oil mass opposite the reciprocating mass?

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The oil mass is added to the rotating weight and opposes the flywheel counterweight. Jim