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Charlie175 
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 Topic: 4" vs. 4.125" pistons
Posted: 26 Dec 2011 at 3:57pm |
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How much performance do the 4.125" give a 226 in a D17? I pulled piston number 1 out to check out the bore and it is 4". Most over haul kits are 4.125". I was just going to put in new rings since it ran good before with only a slight hint of blue smoke at times.
$52 for rings vs. $100 per bore for sleeves/pistons.
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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Gerald J.
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Posted: 26 Dec 2011 at 4:11pm |
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Check the bores for barrel wear, then decide.
Gerald J.
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GregLawlerMinn
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Posted: 26 Dec 2011 at 6:24pm |
Charlie You won't see too much difference in performance with an overbore kit. I prefer to use the standard size kit as they have thicker sleeves. It is a gamble just re-ringing an old engine esp one that is 50 +/- years old and most likely has many hours on it. You need to be sure that your bores are true (top to bottom), are round, and the piston/sleeve clearance is good. You should also be sure the O-rings on the sleeves are good, esp if the tractor has been setting for awhile. You should also check the crank bearing clearances and the camshaft bushings; and don't forget to check out the head/valves (worn valve guides can cause blue smoke). If you are going to use the tractor, an engine kit with new sleeves/pistons/rings and bearings and some machine work is a good investment. I am currently rebuilding a CA engine that an earlier owner redid the engine. After tear down, it was obvious that the engine work was a "just to get by" job. They installed new rings, ground the crank shaft 0.020, re-shimmed the bearings, and polished the valve seats. When I tore it down I discovered open cracks between the cylinders and the deck was sunk so much that it would need 0.050 removed to square it up and the cam bushings were really worn. The cylinder head had thru cracks into the water jacket that leaked under pressure; and the valves/springs/guides were shot. Thus far I have replaced the block (and had it re-decked for the new sleeves and new cam bushings), replaced the head and had it rebuilt with new springs/valves/exhaust seats/guides, and had the crankshaft reground as one rod journal had too much clearance for the bearing (greater than 0.005; did not even squeeze the plasti-gage). Am looking forward to working the tractor next summer, it will be a noticeable increase in power than last summer.
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What this country needs is more unemployed politicians-and lawyers.
Currently have: 1 D14 and a D15S2.
With new owners: 2Bs,9CAs,1WD,2 D12s,5D14s,3D15S2s, 2D17SIVs,D17D,1D19D;1 Unstyled WC
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B26240
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Posted: 26 Dec 2011 at 6:35pm |
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Someone on this forum said 4.125 bore gives 241 cu. in. with 41/2 in. stroke
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DrAllis
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Posted: 26 Dec 2011 at 6:39pm |
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A std D17 4 inch bore has 7.25 to 1 compression ratio and will make equal HP to some/many of these 4.125" bore kits that only have 6.5 to 1 compression ratio and will use more gasoline per hr.
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Charlie175
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Posted: 26 Dec 2011 at 7:01pm |
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If needing replacement I was hoping to go with the 170 8.25 to 1 pistons.
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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HagerAC
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Posted: 26 Dec 2011 at 9:08pm |
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I priced several overhaul kits today, and found that the oversize kit was the cheapest of them all. Thinking thats the way I will go.
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30+ A-Cs ranging from a 1928 20-35, to a 1984 8070FWA, Gleaner R52
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mlpankey
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Posted: 26 Dec 2011 at 9:15pm |
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no replacement for displacement. 4 1/8 bore yields 241 cubic inches and of coarse the bigger the boy the more he wants to eat.
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XT in pa
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Posted: 26 Dec 2011 at 9:30pm |
my 17 that i rebuilt last winter has the 4 1/8 kit in it made 63 hp on dyno i think thats good but also used 80 gal of gas to plant 60 acres of corn with a 4rn 600.
Shawn
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190XT,D17and 7045
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m16ty
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Posted: 26 Dec 2011 at 9:33pm |
 mlpankey wrote:
no replacement for displacement. 4 1/8 bore yields 241 cubic inches and of coarse the bigger the boy the more he wants to eat. |
I agree. I see no reason why you wouldn't go with the 4.125" if you were rebuilding. Sure the sleeves are thinner on the overbore kits but the 4" sleeves are way thicker than needed and cracking sleeves have never been a problem anyway. I've got a WD45 with 4.125" M&W pistons and it will out-do a 175 if you can keep it hooked to the ground.
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DrAllis
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Posted: 26 Dec 2011 at 10:08pm |
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M&W pistons are actually better (more compression ..7.5 to 1) than any of todays 4.125" over-bore kits. The best power and economy will come from OEM 4 inch bore kits with 8.0 or 8.25 to 1 compression versus any 4.125" bore with 6.0 or 6.5 to 1 compression. Sorry boys, too many years of actual dyno testing to tell you anything different.
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skipwelte
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Posted: 26 Dec 2011 at 10:24pm |
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I agree with the Doc, the 4" bore will get more compression than the 4 1//8. Check your wrist pin to top of piston heigth and youll see the difference. " There is no replacement for displacement, but compression is still king, go with more compression!!!"
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m16ty
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Posted: 26 Dec 2011 at 10:39pm |
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I haven't shopped for rebuild kits lately but I have to wonder why nobody offers a 4.125" bore with 8:1 compression?
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Lonn
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Posted: 27 Dec 2011 at 7:13am |
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The Doctor is right.
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-- --- .... .- -- -- .- -.. / .-- .- ... / .- / -- ..- .-. -.. . .-. .. -. --. / -.-. .... .. .-.. -.. / .-. .- .--. .. ... -
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Charlie175
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Posted: 27 Dec 2011 at 8:13am |
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Are the 8/8.25" OEM pistons flat or Power Crater?
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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SteveM C/IL
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Posted: 27 Dec 2011 at 8:28am |
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Don't know but AC designed them so I wouldn't care. If I had it to do over,I'd put the 170(8:1) kits in.[175-was 8.25:1] Around $200 more than the Power Seal M&W over bore but they cut the comp to 6.5. It doesn't have the power it used to have with the original M&W's. Probably only use the D17 pistons in a bypass oil engine...maybe,maybe not?
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Lonn
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Posted: 27 Dec 2011 at 9:01am |
Charlie175 wrote:
Are the 8/8.25" OEM pistons flat or Power Crater? |
Power Crater
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-- --- .... .- -- -- .- -.. / .-- .- ... / .- / -- ..- .-. -.. . .-. .. -. --. / -.-. .... .. .-.. -.. / .-. .- .--. .. ... -
Wink
I am a Russian Bot
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nyacdon
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Posted: 27 Dec 2011 at 9:23pm |
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you fellows are missing something--201 4 1/8 engine kit on a 226 crank--be sure and check clearances and if you have to lathe trim the tops be sure and gram scale them so as not to upset the balance and be sure to use "good fuel".D17's with this treatment will put a smile on your face.
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DrAllis
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Posted: 27 Dec 2011 at 9:58pm |
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Not missing a thing. What you have proposed will (I believe) raise the compression ratio to maybe 9 to 1 ?? or maybe 10 to 1 ?? or more?? here's the facts....8.25 to 1 compression ratio is the MAXIMUM compression ratio these engines can stand with regular 87 octane gasoline. Sure, what you are suggesting will make things run very well, but who's going to buy racing gas for a tractor to farm with???????????????
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mlpankey
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Posted: 28 Dec 2011 at 8:06am |
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who buys a late 50 to early 60s tractor to farm with? untill you get to a 11.1 you shouldnt need racing gas unless yor trying to run the stock hot spark plugs. all i am saying is a 226 at 8.1 compression wouldnt run with 240 cubic inch motor at the same compression. even m&w advertised the 4 1/8 bore with the same compression ratio made 8 horses more than the stock 201 wc at same compression ratio. Dr. Allis is a smart man but a few years back he was attempting to sell 4.250 bores for the guys who wanted a little more from a 226.
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DrAllis
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Posted: 28 Dec 2011 at 8:50am |
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The attempt was for tractor pullers if I remember correctly, not a farm tractor, in an attempt to go with the largest bore possible without having to bore/machine the block. Regardless, a 240 inch at 8 to 1 will surely make more HP than a 226 at 8 to 1......I never said anything any different....apples to apples not apples to grapefruit. The trouble is finding the correct comp ratio. I don't have my old M&W spec sheet anymore, but I'm real sure any kit had more compression than OEM and was 1/8" overbore to boot. And you are dead wrong.....you check ANY farm tractor gasoline (not LP) or any HD truck engine from the last 30 or 40 years and I seriously doubt if you find ANY above 8.2 to 1 compression.....must be a reason for that.....duh!! detonation under load with regular gas!!!!
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Butch(OH)
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Posted: 28 Dec 2011 at 9:00am |
mlpankey wrote:
untill you get to a 11.1 you shouldnt need racing gas unless yor trying to run the stock hot spark plugs. . |
At 11-1 the only way to prevent detonation with 87 octane fuel is to REMOVE the plugs. Last I knew they dont make much power that way, LOL
Edited by Butch(OH) - 28 Dec 2011 at 9:03am
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mlpankey
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Posted: 28 Dec 2011 at 4:35pm |
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well maybe i gave Dr and Larry to much credit. every new gm 400 hp small block chevy from the corvette camaro or gto has a compression ratio of 10.9.1 . A 11.1.1 static compression ratio may be quiet a bit less at dynamic compression ratio due to the intake valve closing point abdc. The spark plug is the cylinders thermostat run a colder spark plug runs a cylinder without detonation. When you advance the cam one tooth to make it pull better the cylinder pressure goes up because the intake valve closes sooner abdc and you gain that torque from that cr increase. The smaller the bore the more comp you can run without detonation. Ran A 5.75 stroke 4 1/8 bore at 11.1 static on 91 with the cam on a 112 center and ngk -9 racing plugs. Ran 15.1 on a 106 cam center ngk-10 race plugs on 110 race gas.
Edited by mlpankey - 28 Dec 2011 at 5:02pm
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mlpankey
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Posted: 28 Dec 2011 at 5:03pm |
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anyone willing to wager? that i can duplicate the above post
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DrAllis
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Posted: 28 Dec 2011 at 5:15pm |
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Spend some quality time and find me a farm tractor or truck engine that runs on regular gasoline (#87 octane or less) and has a compression ratio of MORE than 8.2 to 1 and was built in the 1960's thru 1990 and doesn't have any kind of computer controlled ignition timing. I don't think you'll find any.This is the kind of engine I'm talking about, not a damn modern day race car.
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Charlie175
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Posted: 28 Dec 2011 at 5:21pm |
So the HC kits I see are just W201 style pistons? Price wise the kits are close in cost, but what odd behavior am I going to have with W201 flat top pistons? Hard starting? Higher fuel consumption? Blown head gaskets? I priced up OEM 8/8.25:1 today and they are out of my price range. So it's either W201 or 4.125" (Medium Compression??) I haven't seen a kit with 4" other than OEM I'm not looking to have a barn queen, but something I can use and also pull with.
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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mlpankey
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Posted: 28 Dec 2011 at 5:32pm |
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Go with the bigger bore . Borex bore x stroke x number of cylinders x .7854 is the formula for displacement. Bore counts twice. It does on a flowbench as well take a head do nothing more than increase the bore fixture size and watch the airflow go up each time the bore is increased. Race cars middle income housewifes drive them for grocery getting everyday.
Edited by mlpankey - 28 Dec 2011 at 5:38pm
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Charlie175
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Posted: 28 Dec 2011 at 5:41pm |
mlpankey wrote:
Go with the bigger bore ... middle income housewifes drive them for grocery getting everyday. |
Ha! you made a funny!
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Charlie
'48 B, '51 CA, '56 WD45 '61 D17, '63 D12, '65 D10 , '68 One-Ninety XTD
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mlpankey
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Posted: 28 Dec 2011 at 5:51pm |
high compression on low octane every lawn mower chaisaw and weed eater ran last summer with gas prices where they are now. by the way the more ethanol that goes into a gallon the more cr you will be able to run as well
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Ryan Renko
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Posted: 28 Dec 2011 at 6:26pm |
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I have a M&W brochure. In a wd with standard 4.00" pistons it has 201.1 ci. With the 4 1/8" M&Ws installed it has 213.8 ci and a horse power increase of 5-7 horse power. I just threw this into the topic but really dont have the knowledge to dispute anyones ideas. Ryan
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