Pulling Forum - In a Quandry!

In a Quandry!

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Forum Name: Pulling Forum
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=66983
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Topic: In a Quandry!

Posted By: dgerth
Subject: In a Quandry!
Date Posted: 15 Mar 2013 at 10:23pm

Gentlemen,

Trying to build a Gleaner 226 motor with the 201 pistons. I have new overbore pistons with liners. The problem is the deck height is .550 instead of .350 so the comp ratio will only be about 8.25 to 1 instead of in the 12 to 1 range that I'm striving for. My supplier

says that these are the correct pistons but they don't measure out. Are pistons no longer available to build a hi-comp application such as this? Everything measures out, crank, rods,

etc are stock all appears to be correct except for the piston height. Anyone had this problem before?

tks,

Replies:

Posted By: DrAllis
Date Posted: 16 Mar 2013 at 6:17am

This has been my contention for about 20 years.....the after-market pistons don't have enough compression as compared to OEM stock 4 inch bore (and use more gas to boot). There may be another supplier out there who has what you want, but yours must be only about 6 to 1 comp ratio on a 4 inch stroke crankshaft? I know a guy who used to lengthen connecting rods by cutting and welding them back together up near the piston pin end.

Posted By: CAL(KS)
Date Posted: 16 Mar 2013 at 6:25am

to clarify, your saying you have .550 from top of piston to top of block instead of the desired .350? deck height is from centerline of crank to top of block not from top of piston. we need the compression height of your pistons to compare. i dont have any numbers for you but someone will

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Me -C,U,UC,WC,WD45,190XT,TL-12,145T,HD6G,HD16,HD20

Dad- WD, D17D, D19D, RT100A, 7020, 7080,7580, 2-8550's, 2-S77, HD15

Posted By: mlpankey
Date Posted: 16 Mar 2013 at 6:51am

Yeap i have always said that wc wd pistons on a 4.5 crank is a 175 series 226 . You can pick up some by decking the block oring the sleeves and not use a head gasket but it will not make up 4 points.

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people if they don't already know it you can't tell them. quote yogi berra

Posted By: THE-MAN
Date Posted: 16 Mar 2013 at 7:15pm

Oooor you could offset gring your crank to buda rods and go up to the 240 + inch area, have more compression, and more stroke, and not have to mess with o ringing anything, run a stock gasket and have an equally durable engine. If you need to tweak your c.r. offset your pin bushing or cut a bit off your piston. There is plenty there.

Posted By: dgerth
Date Posted: 16 Mar 2013 at 8:12pm

Thank you gentlemen,

Now., comes the big one, where does one get the correct 201 pistons to build one of these engines? The set that I have now will not get the job done. Anyone have input on this ?

tks again,

Posted By: WCCLASON
Date Posted: 16 Mar 2013 at 10:32pm

Its funny this subject came up. I have built two motors to this spec. you are trying to get to.

To be to the point. The first time i was lucky enough to find a set of 4 1/8 power craters that will give you serious compresion! The top edge of the power crater pistons i run are 2 or 3/32nds from the top or the deck. So the chamber is pretty much the area of the crater in the piston.
This is the engine i am still playing with and trying to get dialed in. The other i tryed to order wc Piston like you said to get the high comp. i wanted. I got them and they were wrong! they were the .500 from the deck like you said. I called the piston distributer and argued with him saying they were wrong....He sent me a new set of pistons that come to find out were the same. So i got 2 sets for the price of one. And those are now in one of my motors and actually runs really well.

Sorry.....Back to subject.....Like the other said. I think unless you can find a used set of WD or WC pistons i dont know were you could get them. Might be possable that WC pistons will give you higher comp because the were rated for lower comp. which means the wrist pin was located lower in the piston from factory.

Another option but is more work, Find a used set of 4 1/8 M&W pistons for a WD/WC and have them milled the way you want them to . If i remember right they stick out of the block about a 1/4 or maybe more with just a WD45 crank. Then you could mill them to the depth you want. Within reason. Not to get the top of your piston to thin.

Ok hope that helps..... Just my 2 Cents and what i know/Learned

Posted By: wi50
Date Posted: 18 Mar 2013 at 1:58pm

I have some old take out pistons from a WD, I don't have the part number on them right now but they are 4" flat top with a 2.5 or 2.505 compression height. Figureing a few CC of volume for the spark plug pocket and a stock head gasket, that would make 11.1 : 1 compression ratio when used with a stock 4.5" stroke crank and stock 7.5" connecting rods.

In it's original application this was a 6.7 : 1 compression ratio. I do not know the specs on any new aftermarket pistons.

Block deck height is 12.625"

Rod is 7.5" center to center

Crank stroke is 4.5" so use 2.25" for figureing your deck clearance

I wanted a pretty cheap and easy engine for one so I traded some junk for a used a set of M&W pistons from a WD-WC. They are right about a 2.94 compression height with a 70CC dish. This put them .065" above the block deck. I bought a new set of sleves and rings. Trimmed the pistons for a bit of a pop out so I could get a good quench to the head and I cut valve reliefs in and trimmed the piston bowls for a total of 92CC. I shot for an 11.25 : 1 compression ratio. Degreed a stock cam for the engine to 105* intake centerline. Did a bunch of head, carb, manifold and ignition work for it.

If I were going to do it again, and not spend a lot of money to build a smaller cheap engine I'd probably bore a set of Allis 4 1/8 sleves over to accept John Deere 3010-4010 gas tractor pistons, offset grind the Allis crank for use with Buda 262 connectiong rods and trim the pistons and bowls out for desired compression ratio.... this would give a guy a 266-269 CID engine with out pouring a pile of time, money and custom parts in. I do need to measure some of the John Deere pistons again to make sure, I just measured some one day at the salvage yard and thought they were a good cantidate for something like this.

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"see what happens when you have no practical experience doing something...... you end up playing with calculators and looking stupid on the internet"

Posted By: WCCLASON
Date Posted: 18 Mar 2013 at 2:24pm

Good point marty. Rules are also a big key. Are club will only let us go 10% over stock cubes, or somthing it was like 249 and no bigger. So that is why i only build small CI motors, but after going to Sigourney i think its time to build a mean motor....Or start an new project....I have a friend with a nice 77 oliver i could start with....Alot of F20 F30 tractors my family has i could build but heard that cranks wont hold. Or just build a bigger motor for my WC.