Board index Flathead Power-Technical Questions, Answers, and Suggestions Indians Need huge Chief piston

Need huge Chief piston

Moderators: Curt!, Pa

Post Wed Oct 24, 2001 1:10 pm

Posts: 3010
Location: Central Illinois, USA
Does anyone know of a source for extreme overbore Chief pistons, or unground blanks?

Post Wed Oct 24, 2001 3:54 pm

Posts: 1319
Location: State College, Pa.
You might want to try

Egge Machine Co.
(800) 634-2645
fax (213) 693-1638

Post Wed Oct 24, 2001 3:56 pm

Posts: 1050
Location: Greenbackville, Virginia, USA
Egge Machine has always been good to me.

Post Thu Oct 25, 2001 1:30 am
don User avatar

Posts: 571
Location: Spokane WA USA
Website; with online form

Post Thu Oct 25, 2001 3:25 am

Posts: 3010
Location: Central Illinois, USA
I bought the last of Egge's stock a year and a half ago. They ground a set each of .070"s and .080"s for me, which used up all of their Robbins mold blanks.

They are out of Bonnies also, and have no expectations of casting any more, unless you order a thousand or so.

But I clumbsily chipped the skirt on one of the .080"s upon final assembly of a balanced motor.....!

(I am fortunate to have a patient customer.)

So I have been beating the bushes for another blank that is big enough, as a Lynite blank from Mr. Myles couldn't be cut by Egge big enough.
I would think you could index a workpiece to within a thou or two, but Egge needs .008" to .012" of extra meat to cam-grind the thrust faces.

I have had an encouraging response already, and hope to have another pair of Robbins blanks soon.

Thanks to all for the replies!

PS Question: Has anyone had experience with such gross overbores on a Chief?

Post Thu Oct 25, 2001 6:14 am

Posts: 896
Location: Bixby,OK, USA
I'm curious to know how it works as I have a .050 and a .070 cyl that I would like to use.

Post Thu Oct 25, 2001 6:44 am

Posts: 1319
Location: State College, Pa.
I believe, last year at Oley, I ran across .100 overs and/or semi finnished at one of the booths. I'll have to snag them up for ya. Slight possibility there might be somethin in the upper building of the Brit shop. I know we got new factory Injun pistons there.


Post Thu Oct 25, 2001 1:03 pm

Posts: 3010
Location: Central Illinois, USA
Thanks for the offer Hoot, but I think a pair are already heading my way. (This computer-thang is good for something after all!)

And Boog! It works like any other gross overbore: You have to use torqueplates
and probably stuff a hole back up in the counterweigh portion of the flywheel for balance.

I ran a stroked pan at .050" low compression on the rear against a .080" standard compression front for a while. The motor did not seem to mind, as even the plugs burned the same.......!?!

Post Thu Oct 25, 2001 3:11 pm

Posts: 1319
Location: State College, Pa.
I remember reading in a HD manual that running .020 difference between cylinders is acceptable.


Post Sun Oct 28, 2001 4:43 am

Posts: 896
Location: Bixby,OK, USA
Thanks for the reply guys. I'll have to post the pictures of my torque plates for you Cotten. I think the top is 1.5 inch aluminum, and the bottom is a 1/2 grouond steel pattern plate. I'm in the process of building some pins to fit the holes in the top plate, and the holes in the heads, with the middle being a larger OD. I'm going to use them to hold the head to machine the combustion chamber for compensating for the 80" stroke. I think it will allow me to clamp them good and not damage the fins.
So if a guy wants to really ride his chief, how far over is safe? On the next one I have to build, (mine) I intend to go 84" with Kiwi's rods and I guess FHP cylinders. I have a bad habit of riding a bit hard. so I need to build in a little endurance. I sure would like to use those cylinders though.

Post Sun Oct 28, 2001 4:49 pm

Posts: 3010
Location: Central Illinois, USA
The top plate in the picture above is magnesium printer's plate. It keeps the weight down for my back's sake, since I cannot get this gross assembly into my honing tank, and must do in on the floor in a drip pan I have made to hold it by the top plate. The bottom plate is some kind of aluminum billet. I found that the top plate gives very little distortion of the bore or valveseats at 55 ft/lbs.
But the bottom plate does this even at normal overbores, and much less torque (28 to 32 ft/lbs):
You can see the shadows where the Sunnen stone sweeps over depressions caused by the fastener torque. This is NOTHING compared to the distortion of Harley cylinders! (H-D's big spigots must give the fastener stress something to push against, plus I torque them at 40 ft/lbs.)

Post Fri Nov 02, 2001 2:15 pm

Posts: 3010
Location: Central Illinois, USA
I'm still in trouble!
A VirtualIndian Lister graciously sent me a Robbins blank to get me out of
my bind over the skirt I chipped. But Egge told me they usually scrap six or
eight just to set their machines up!

Where else can I send a raw piston casting for machining?

Post Wed Nov 28, 2001 3:23 am

Posts: 188
Location: howell mi usa
Cotten, have you tried some of the auto perf. piston man. J.E, Ross, Wiseco, etc. on custom pistons. some of them will make custom pistons with a min. of 4. they're making alot of import 4 cyl. stuff and should have blanks close to the Indian Chief size or whatever. I have also started fusion sleeving Indian jugs now. So far so good, the stuff seems to work well.

Post Wed Nov 28, 2001 3:51 am

Posts: 3010
Location: Central Illinois, USA
Ross Performance Pistons is on the case! Updates to follow, if I am reminded..

Post Fri Nov 30, 2001 4:57 am

Posts: 6
Location: bel air md. usa
cotten ..... give the boys at Venolia a shout , they'll do onezy and toozys minimum last i knew of

[This message has been edited by meatball45e (edited 30 November 2001).]

Post Fri Nov 30, 2001 2:04 pm

Posts: 3010
Location: Central Illinois, USA
Too late, the Ross pistons are being made. (I might break another one anyway!)

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