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74" flywheels in a 1939 EL

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Cotten

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Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Sun Oct 17, 1999 3:01 pm

Yes, all BT wheels through '54 (no shovels)can be made to fit, with scraper alterations. They are heavier than your pre-war units though, so you will lose performance for a light solo machine, but gain some torque for a heavy ol' Lady payload. Ideally you should look for some flatty (U)wheels, as they are the same original diameter, but a healthy stroke. Note:I like my 61" lowers with 74" upper ends just fine. One is close to 70" anyway.

[This message has been edited by Cotten (edited 17 October 1999).]
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Cotten

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Post Mon Oct 18, 1999 3:14 am

It has been traditional to just use high (10:1) compression 74" pistons with the short stroke to come back to normal range. These are heavier and you will want to rebalance, of course. (I did open up a Pan once with a 61" crank and standard compression pistons; It ran,.. but I bet it was a dog.)
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booger

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Joined: Thu Oct 07, 1999 12:01 am

Location: Bear Swamp,NC CSA

Post Mon Oct 18, 1999 8:35 pm

Be fore warned that early cases can be pretty weak on the left hand side.
EL 's tend to run smoother than a 74" ...less vibration anyway ...that has been my experience ...I'd stick with the 61" wheels and run the big top ...it is a very usable combination ...you don't need a lot of compression with these machines unless you want to hot rod ..and i have big port heads ona 61" jugs and wheels ..in a '38 el ..and she's smooth Image
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filthy

Posts: 136

Joined: Thu Sep 30, 1999 12:01 am

Location: oxford, NC USA

Post Wed Oct 20, 1999 1:30 pm

It'll work.

Have a friend running an EL Pan with the big top end. He took a cut on the cylinder bases to get it right.

A nice, smooth engine that is stronger than many.

filthy
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panic

Post Thu Oct 21, 1999 1:41 am

Barrel heights for OHV twins (head gasket surface to base gasket surface):
1936-47 EL 5.405"
1941-47 FL 5.53
1948-52 EL 5.205
1948-83 FL 5.33
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filthy

Posts: 136

Joined: Thu Sep 30, 1999 12:01 am

Location: oxford, NC USA

Post Thu Oct 21, 1999 2:54 pm

Yeah. But you've also got to cut down the intake maniflod as the ports will also be closer. Couple of other odd, little things, but I don't remember. Roland told me it was an easy job.

Luck,

filthy
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Cotten

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Post Fri Oct 22, 1999 2:18 am

Now I'm confused! You shouldn't have to cut your cylinders at all! Even if you converted to 74" cylinders you will still have decent compression; Remember the additional displacement has increased the compression also.
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filthy

Posts: 136

Joined: Thu Sep 30, 1999 12:01 am

Location: oxford, NC USA

Post Sat Oct 23, 1999 1:39 am

uh-uh.

The larger cylinders have only increased cylinder voulmn. But due to the shorter stroke, the chamber volumn is increased also, leading to lower compression with a STOCK piston. Running the EL wheels under an FL top is the equivelent of de-stroking, and from what I've seen of this Pan, it ain't a bad idea.

Dunno what compression Roland runs, but it's some higher than stock. But he is also not running stock pistons.

How's that set of heads coming?

filthy
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filthy

Posts: 136

Joined: Thu Sep 30, 1999 12:01 am

Location: oxford, NC USA

Post Mon Oct 25, 1999 3:11 am

Hi,

Sounds like you've got a plan, Sounds good.

With the comp and pistons you propose, you shouldn't have any valve clearence problems unless you cam it so tall it might not run anyway.

Be careful you don't take too big a cut. I would think that the difference in the 61 / 74 stroke should be about right, but I only know what I've been told about it. Never personaly done it. Reccomend that you do the math.

Luck,

filthy
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Dusty-Dave

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Joined: Tue Oct 12, 1999 12:01 am

Location: Ojo Caliente,NM,USA

Post Mon Oct 25, 1999 5:17 am

Larry:
To check valve to piston clearance. Assemble the topend with used head gaskets the same thickness as you are going to use and some modeling clay (steal it fron your rug rats or the neighbors)on top of the piston in the valve areas. Adjust the valves to normal clearances unless you have hydralics witch have to be adjusted all the way to the bottom of their travel (I remove the springs and make a little shim so they adjust lke a solid fot the test). Rotate in the normal direction of travel 2 or 3 rounds. Remove the heads and mike the clay. I wouldn't suggest less than .040 on a Hardley.
dusty
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Cotten

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Location: Central Illinois, USA

Post Mon Oct 25, 1999 1:41 pm

You are doing it the hard, expensive way, but I'll defend to the death your right to cut up anything you want. (I often do.) Picking a proper piston is easier than cutting cylinders, cutting manifolds, etc., and it's not a one-way trip for your hardware. Your balancing will be a lot simpler also. Most EL's that have come through my shop in two decades have already been shot out to 3 7/16th plus, and some even had shovel tops!
Cotten
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geronimo

Posts: 11

Joined: Sat Oct 02, 1999 12:01 am

Post Tue Oct 26, 1999 2:25 am

Hello Larry;
I'm also in the mitts of an old knucklehead. when i popped it apart,it had 74" jugs that where cut down to 5.405". it had medium comp. shovelhead pistons. Both cylinder's where cracked and sleeved,an ugly sight, i bought an set of 61" cylinder's that where +.020" for $300., at an AMCA meet in Wauseon,OH. I bought my piston's and assoicated parts from Kick-Start motorcycle parts inc.
Good luck!

------------------
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geronimo

Posts: 11

Joined: Sat Oct 02, 1999 12:01 am

Post Wed Oct 27, 1999 1:34 am

Larry;
You'll have to send an check or money order for $5 to Kick-start motorcycle parts inc.
P.O. box 9347
Wyoming, Michigan 49509
Chuck that runs it doesn't want anything to do with the internet.
I suggest that you buy the book How to restore your Harley-Davidson, by Bruce Palmer
or sometimes called the bible from hell.
It does a very good job of identifying and explaning the how,what,and whys.
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dotman

Posts: 582

Joined: Fri Oct 01, 1999 12:01 am

Location: meridian, id. usa

Post Wed Oct 27, 1999 3:03 am

Chuck's a good guy and has a great cataloge.
And he usually has most everything in stock
so ya dont have to wait and if he doesnt he tells u up front.
And I agree with Geronimo about palmers book
good but straight from the hell of the restoRATion demons.
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panic

Post Wed Oct 27, 1999 11:55 am

Yes, the extra height is in the compression distance of the EL pistons. I would prefer a custom piston myself to shortening the barrels (if you insist - why not cut up a repro barrel instead? get one from KNS Cycle)
For Palmer's book, click here.

[This message has been edited by panic (edited 27 October 1999).]

[This message has been edited by panic (edited 28 October 1999).]
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dotman

Posts: 582

Joined: Fri Oct 01, 1999 12:01 am

Location: meridian, id. usa

Post Sun Oct 31, 1999 5:26 am

dont think you can elec. weld cast but ive used nickel brass to flame braze cast with good results. you might be able to get iron rod to flow right if you use the right flux and keep the flame moving around to equalize the heat,
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Cotten

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Joined: Thu Sep 30, 1999 12:01 am

Location: Central Illinois, USA

Post Sun Oct 31, 1999 3:24 pm

Weld repair on cast iron can take up a whole new thread! Please post a new topic question, and tell us what and where your hardware is cracked or broken.
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