B,C,CA Pistons
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Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=44499
Printed Date: 22 Aug 2025 at 2:31am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: B,C,CA Pistons
Posted By: SteveC(NS)
Subject: B,C,CA Pistons
Date Posted: 26 Jan 2012 at 3:36pm
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Does anyone know of a supplier who sells 3.4375" pistons with a wrist pin c/l-to piston top of 1.950 inches or thereabouts? I have M&W "add power" pistons and would like to increase my compression ratio. The M & W pistons are only 1.881 and come to below the std. .032" to the block.
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Replies:
Posted By: SteveC(NS)
Date Posted: 27 Jan 2012 at 1:57pm
| Okay folks, either I'm being shunned or NOBODY makes or sells 3 7/16" B,C, CA pistons? with a std. pin to top height. Norm,Jim,Tony ??? |
Posted By: Dick L
Date Posted: 27 Jan 2012 at 4:20pm
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The last set I bought were flush with the top of the block. I would have to dig to find where I bought them. Check with Hastings direct. I have bought several sets of rings from them.
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Posted By: SteveC(NS)
Date Posted: 27 Jan 2012 at 6:32pm
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Dick, flush with the top of the block would be fantastic! Can I buy them through you or would I have to go to hastings direct. I tried to PM you but it doesn`t look like it worked. I`ll try to pm you with this message.
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Posted By: SteveC(NS)
Date Posted: 28 Jan 2012 at 10:03am
| Dick, I couldn't find Hastings Direct, have you got an URL for them? |
Posted By: CTuckerNWIL
Date Posted: 28 Jan 2012 at 10:40am
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Don't look for Hastings Direct. Look for Hasting piston rings.
------------- http://www.ae-ta.com" rel="nofollow - http://www.ae-ta.com Lena 1935 WC12xxx, Willie 1951 CA6xx Dad bought new, 1954WD45 PS, 1960 D17 NF |
Posted By: Dick L
Date Posted: 28 Jan 2012 at 10:57am
I have been covered up and didn't get to spend computer time. What I meant by Hastings direct was to not go through a dealer. I got back on the last PM the first didn't have a measage when I just opened it up.
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SteveC(NS) wrote:Posted By: steve(ill)
Date Posted: 28 Jan 2012 at 11:03am
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Hastings sells great piston rings. I did not know they sold pistons for the B. Most oversize kits that everyone here sells will be 3-7/16 bore. I dont ever remember anyone asking what the height was relative to the pin. I cant say for sure, but i though several of the motors i had rebuilt had the piston flush with the deck. Guess i never really measured to be exact..... You can also cut .100 off the head face-- talk to Dick about it. ------------- Like them all, but love the "B"s. |
Posted By: SteveC(NS)
Date Posted: 29 Jan 2012 at 10:00am
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By my calculations if I mill .100" off the head it raises my comp. ratio from the existing 6.41 to 1 up to 7.027to one. But if I could get pistons .100" taller, as in even with the top of the block, it would raise my compression ratio to 7.394 to one. And if I were to combine head milling and flush with top of block pistons I would get 8.28-to one compression ratio which isn't unreasonably high by today's standards. My big question would be how much increase in HP could I expect and would I be inviting pre-ignition and sarting problems? |
Posted By: Dick L
Date Posted: 29 Jan 2012 at 11:42am
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I took half of my pistons above the block .200 and took .150 off the head on my C I pulled with along with going to a 4 inch stroke. No problems with starting or pre ignition. I don't think you will hear and problems in the sound. http://www.youtube.com/watch?v=hM4YbM8keMM" rel="nofollow - http://www.youtube.com/watch?v=hM4YbM8keMM I took .200 off the head on the B on a 4 inch stroke and took half of the piston into the head about .125 The B taking second in the 3000 pound class where I took first in the same class with the C. The video was at a different pull though.  |
Posted By: SteveC(NS)
Date Posted: 30 Jan 2012 at 7:55am
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Thanks Dick, enjoyed the video. If I can't find anyone to supply the higher 3 7/16" pistons I may pop the liners and mill the block then bore for the liner lip. Off hand is there enough room on the O'ring area of the block to seal liners that are .100" lower?
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Posted By: Dick L
Date Posted: 30 Jan 2012 at 11:32am
| I think you would loose the bottom one. I have a coupla engines apart in my home shop. Kinda cold but after I get chores done tonight and get Jason his O rings and I aint to cold I will check for sure. |
Posted By: SteveC(NS)
Date Posted: 30 Jan 2012 at 3:40pm
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Thanks Dick, I know what a cold shop is like. Today, however, I turned on the heater and lit the little Jotul so I could do some work. Here's a shot of the first cut off the head.  |
Posted By: Dick L
Date Posted: 31 Jan 2012 at 10:32am
| I checked ant it would just make it if below the old O ring area is pitted you may need to repair that first. Just to be clear I would not do it that way. |
Posted By: SteveC(NS)
Date Posted: 31 Jan 2012 at 7:13pm
| Gotcha Dick I'd rather not do it that way either but I can't believe nobody on this board sells O'size pistons for the B,C,CA. |
Posted By: SteveC(NS)
Date Posted: 09 Feb 2012 at 2:50pm
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I finally found a calculator for determining the horsepower increase derived from an increase in compression http://www.bgsoflex.com/crchange.html" rel="nofollow - http://www.bgsoflex.com/crchange.html tells me that 6.4-1 increased to 8-1 would produce 8% more horsepower. As an increase in piston height would only be a part of that boost to 8-1 I have determined that new pistons would not be worthwhile. So, Jim, I won't be ordering those 3 7/16" pistons and I'll putr the CA engine back together with the M&Ws I now have. Thanks for your help.
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