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The "Cocktail engine" starting to take form

Moderator: David Vizard

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The Iron Icon
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The "Cocktail engine" starting to take form

Post by The Iron Icon » Sun Sep 01, 2019 12:01 pm

Well guys, starting to get parts together for the build. Needless to say I have an interesting mix of rockers. Low ratio for Ex and high for In. Advertised ratios are from 1.5 to 1.72. Real ratios are alot different from that. They range from 1.566 to 1.78. Now for the good question anyone want to donate 2 springs? Got 14 beehives from a set part # comp 26918.
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Re: The "Cocktail engine" starting to take form

Post by David Vizard » Fri Sep 06, 2019 4:33 pm

OK need some input here.

We have an assortment of rods that is 4 at 5.4 long and 4 at 5.09 long.

Any idea's as to how these should be placed in the engine to get the best balance??

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Re: The "Cocktail engine" starting to take form

Post by MadBill » Fri Sep 06, 2019 11:10 pm

I'd alternate long/short in the F.O. sequence, because...well, just because.

I guess the budget wouldn't run to spinning up the short block with various combos and evaluating relative roughness?
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Re: The "Cocktail engine" starting to take form

Post by Stan Weiss » Sat Sep 07, 2019 12:57 pm

I would put the 4 at 5.4 long in one bank and the 4 at 5.09 long in the other bank.

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Re: The "Cocktail engine" starting to take form

Post by MadBill » Sat Sep 07, 2019 5:46 pm

On second thought, I'd alternate long/short on each crank throw.
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Re: The "Cocktail engine" starting to take form

Post by MadBill » Sat Sep 07, 2019 5:49 pm

Or, if balancing is in the budget, pairs of shorts and longs per journal, with bobweights matched accordingly.
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Re: The "Cocktail engine" starting to take form

Post by David Vizard » Wed Nov 13, 2019 10:22 am

Bill,

Balancing is still one of those unknowns for us. What we have to consider is how to balance it with odd rod lengths. I think if the rods have the same end to end weight we will balance as per normal.
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Re: The "Cocktail engine" starting to take form

Post by BCjohnny » Sat Nov 23, 2019 3:48 pm

Depending on the manifold and what your interpretation is of what's going on inside it relative to rpm, you'd want the longer rods on the end four cylinders, or middle four cylinders.

If you think there is plenty of manifold inertial ramming you'd maybe want the longer rods on the end four cylinders ......

If you think the manifold velocity is more stalled you'd maybe want the shorter rods on the end four cylinders ......

So paired on journals long, short, short, long ...... or vice versa.

But I'm probably completely wrong ...... just my tuppence worth, lol ......
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Re: The "Cocktail engine" starting to take form

Post by David Vizard » Wed Dec 04, 2019 12:11 pm

BCjohnny wrote:
Sat Nov 23, 2019 3:48 pm
Depending on the manifold and what your interpretation is of what's going on inside it relative to rpm, you'd want the longer rods on the end four cylinders, or middle four cylinders.

If you think there is plenty of manifold inertial ramming you'd maybe want the longer rods on the end four cylinders ......

If you think the manifold velocity is more stalled you'd maybe want the shorter rods on the end four cylinders ......

So paired on journals long, short, short, long ...... or vice versa.

But I'm probably completely wrong ...... just my tuppence worth, lol ......
Hey BC Johnny,

That suggestion was worth a whole lot more than just two pence.

thanks for the input!
DV
David Vizard Small Group Performance Seminars - held about every 2 months. My shop or yours. Contact for seminar deails - davidvizardseminar@gmail.com for details.

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