Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties VL stroker project Balance factor

VL stroker project Balance factor

Moderators: Curt!, Pa

Post Sat Nov 13, 2010 7:24 am

Posts: 27
Greetings group: Well the VL stroker project is coming along good. Using late (7.440 rods H beam type) Ul piston cut off a little on the bottom with 4 3/4 " T&O flywheels the deck is "O" to the top of jug ,it will be .030 with gasket. doing the bottom end now and was wondering if the 60% balance factor I used to use on my Shovel drag bike would be good on this flathead . Was considering KNS regrind on cams or make my own lobes. more later----Turk

Post Sat Nov 13, 2010 7:41 am

Posts: 3123
Location: Central Illinois, USA
Turk!

My memory fades, but I believe Mr. Slocombe cited the original factor to be quite low: 43%
Reason for the radical difference from later models is the frame design.

A longer stroke will favor a slightly higher factor of course.

....Cotten

Post Sat Nov 13, 2010 8:09 am
panic

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Last edited by panic on Fri Nov 19, 2010 8:31 am, edited 1 time in total.

Post Sat Nov 13, 2010 8:29 am
panic

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Last edited by panic on Fri Nov 19, 2010 8:32 am, edited 1 time in total.

Post Sat Nov 13, 2010 9:20 am

Posts: 27
Panic: I dont have a U cylinder to measure but I suspect it is different than the v which is 6.140 in my case. It came out perfect assembled. would the KNS cams .375-296 be sutable? I want it to get it when nailed from cruising and run good top end. Turk

Post Sat Nov 13, 2010 10:33 am

Posts: 27
Difference may be between Za & Sa rod length

Post Sat Nov 13, 2010 10:55 am
panic

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Last edited by panic on Fri Nov 19, 2010 8:32 am, edited 2 times in total.

Post Sat Nov 13, 2010 2:40 pm

Posts: 27
Panic: I was thinking since the exhaust valve is too big and the port is very good I would leave exhaust cam stock and go with just changeing the intake cam. Will probably use a Kirker 2 into 1 exhaust pipe, 2 1/8 ' super D S&S carb or an M 74-b with 1 5/16 venturi. Thanks for your help---Turk

Post Sat Nov 13, 2010 4:57 pm
panic

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Last edited by panic on Fri Nov 19, 2010 8:33 am, edited 1 time in total.

Post Wed Nov 17, 2010 9:54 pm

Posts: 27
Greetings group: So we will all know,I talked to the owner of the " WORLDS FASTEST FLATHEAD" Paul Friebus,no long disertation or theorys just use 60%, I allways used that on my drag bikes,Chet Wilson race engines balances all harleys at 60%, T&O uses 60% on all there motors. There a sign on a mountain in the himilayas that says 60% and one on a mountain in the andes that says the same. Also S&S recomends 60 % . So I have used that factor. Just got done trueing the Flywheels to within 5 tenths,will set end space and assemble cases tomorrow. I made a cam lobe out of an old piece of 1/2 plate I had laying around .450 lift will degree it and find out what Iv'e got for duration. Just an old fart having fun--more-later---Turk

Post Thu Nov 18, 2010 6:30 am

Posts: 3123
Location: Central Illinois, USA
TURK wrote:
Greetings group: So we will all know,I talked to the owner of the " WORLDS FASTEST FLATHEAD" Paul Friebus,no long disertation or theorys just use 60%, I allways used that on my drag bikes,Chet Wilson race engines balances all harleys at 60%, T&O uses 60% on all there motors. There a sign on a mountain in the himilayas that says 60% and one on a mountain in the andes that says the same. Also S&S recomends 60 % . So I have used that factor. Just got done trueing the Flywheels to within 5 tenths,will set end space and assemble cases tomorrow. I made a cam lobe out of an old piece of 1/2 plate I had laying around .450 lift will degree it and find out what Iv'e got for duration. Just an old fart having fun--more-later---Turk


Its is sad that so much of the genius of the early Twentieth Century has been lost to blind dogma.

....Cotten

Post Thu Nov 18, 2010 9:01 am

Posts: 27
Cotton: What ever do you mean? :D Want to hear somthing interesting? Just found out my old high port dual carb heads and jugs off my old drag bike will fit the VL cases,pushrod angles are better than on shovel,these heads flow 200 cfm at 10" ,with rocker arms the stock VL cams will make .536 lift and may be a little more duration. WaaaH !! another option :wink: Ps We went 9.08 et at 153 mph in quarter on alky with these heads

Post Thu Nov 18, 2010 11:24 am

Posts: 3123
Location: Central Illinois, USA
Turk!

A motor that is balanced appropriately for one frame design is inappropriate for another.

Ever wonder why your machine feels funny if the top motormount comes loose?

For all these revered experts to declare any factor to be universal for all applications is sad. Very sad.

....Cotten

Post Thu Nov 18, 2010 1:15 pm
panic

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Last edited by panic on Fri Nov 19, 2010 8:33 am, edited 1 time in total.

Post Thu Nov 18, 2010 7:59 pm

Posts: 3123
Location: Central Illinois, USA
panic wrote:
I'm still waiting for an answer as to why the rod weight is divided into reciprocating and rotating weight at the center of gravity (for those not familiar with my habits: please, don't explain how an engine is balanced).


Panic!

Most agreeable methods ignore the rod's center of gravity, and just accept each end's mass for what it is .
(As long as they both add up to the total rod weight, of course.)

Why would you care where the rod's center of gravity was?
Am I agreeing with you?

...Cotten

Post Thu Nov 18, 2010 10:56 pm
panic

Wasting my time.
Last edited by panic on Fri Nov 19, 2010 8:30 am, edited 1 time in total.

Post Fri Nov 19, 2010 7:14 am

Posts: 3123
Location: Central Illinois, USA
Panic!

I weigh my rods that way too, because it ignores the rod's center of gravity!
It drops out of the equation when level; I even use a spirit level with adjustable pucks to set the rod up:
balncLVL.jpg
balncLVL.jpg (62.42 KiB) Viewed 9946 times

Goofy methods of balancing the beam on a knife-edge to mark the center of gravity to then proportionally calculate the weights of each end just did not reproduce themselves, when I tried them.

....Cotten

Post Fri Nov 19, 2010 1:00 pm

Posts: 151
Location: Carver, MN

Cotton: What ever do you mean? Want to hear somthing interesting? Just found out my old high port dual carb heads and jugs off my old drag bike will fit the VL cases,pushrod angles are better than on shovel,these heads flow 200 cfm at 10" ,with rocker arms the stock VL cams will make .536 lift and may be a little more duration. WaaaH !! another option Ps We went 9.08 et at 153 mph in quarter on alky with these heads


I am going to go out on a limb here and venture a guess that you must be the world famous Turk Dale, celebrated drag racer of yesteryear. Are you sure it wouldn't be a better use of those heads to restore your drag bike so that future generations can see what drag racing was all about back in the glory days?

Post Fri Nov 19, 2010 6:27 pm

Posts: 27
Lee: I sold the "IRON MISTRESS" to a guy in Texas in about 1990 ? I kept the dual carb heads,had a lot of hours in them. I bought a flow bench just to do those heads. After this VL project is running I'm thinking about a 5.250 x 3.5 flathead on spray,that should take care of the advantage of OHV. I'm almost 75 now, got to keep busy and thinking, Thanks for remembering---Turk

Post Wed Nov 24, 2010 3:46 pm
jib

Posts: 575
Location: devon,england
Cotten wrote:
Turk!

My memory fades, but I believe Mr. Slocombe cited the original factor to be quite low: 43%
Reason for the radical difference from later models is the frame design.

A longer stroke will favor a slightly higher factor of course.

....Cotten


hi turk and cotten

steve has changed the recommended balance factor to 46% which he has got from an old data book

regards jib
Dude, check out that jibhead, he's crazy. Hasn't been sober for 40 years

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