new ap 46 piston made
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=202205
Printed Date: 30 Oct 2025 at 12:27pm
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Topic: new ap 46 piston made
Posted By: HudCo
Subject: new ap 46 piston made
Date Posted: 09 Jul 2024 at 5:45pm
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Replies:
Posted By: Ol case mike
Date Posted: 09 Jul 2024 at 5:48pm
| Do those need 170 cut off the tops still |
Posted By: HudCo
Date Posted: 09 Jul 2024 at 5:50pm
| four brand new ap 46 just waiting on the d17 crank so we can decide on compression ratio i had the pin hieght and the bowls the same as my sample piston we will see how much to mill |
Posted By: HudCo
Date Posted: 09 Jul 2024 at 5:54pm
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Posted By: DrAllis
Date Posted: 09 Jul 2024 at 5:55pm
| NOW WE"RE GETTING SOMETHING DONE !!!! Remember to mark the flywheel for 20 and 22 degree BTDC because that is where you need to be. |
Posted By: Thymansrepairandcust
Date Posted: 09 Jul 2024 at 5:55pm
| Im interested in a set of these if they are available. And will come back to see if they do need milling or not for a d17 |
Posted By: steve fischer
Date Posted: 09 Jul 2024 at 6:40pm
| Is that the sample I sent you |
Posted By: HudCo
Date Posted: 09 Jul 2024 at 9:45pm
| yes sir steve i still thank you i am keeping it on file in case you need it agian |
Posted By: HudCo
Date Posted: 09 Jul 2024 at 9:48pm
| how much compression am i going to be with out milling the top ? i cant waite to get the crank back so i see what volume i have at tdc |
Posted By: DrAllis
Date Posted: 10 Jul 2024 at 8:07am
| When I used SP-46 pistons I had to remove .170" from the outer top lip because the piston would hit the cylinder head !!! I had 240 psi of cranking compression and always felt it was around 11 to 1 ratio. 110 octane fuel was easily good enough along with retarded ignition timing of 20 to 22 degrees BTDC at full throttle. |
Posted By: WF owner
Date Posted: 11 Jul 2024 at 3:11pm
| Just a question, but if they are custom building the pistons, couldn't they shave .170 from the top or move the wrist pin up .170 during the build? |
Posted By: DrAllis
Date Posted: 11 Jul 2024 at 3:27pm
| Sure. They have to be told exactly what you want and they will make it like that. |
Posted By: NEVER green
Date Posted: 12 Jul 2024 at 9:21am
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If they were mine I would like the ring pack higher, I guess with the bowl so big - wide there is not enough material. ------------- 2-8050 1-7080 6080 D-19 modelE & A 7040 R50 |
Posted By: DrAllis
Date Posted: 12 Jul 2024 at 10:30am
| I would have preferred the top ring height match the old pistons location to keep the compression exactly the same. I know it will be a very slight difference. |
Posted By: WF owner
Date Posted: 12 Jul 2024 at 2:20pm
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I remember talking to Don Bradley several years ago and he was totally against using flat-top pistons. He claimed Power Crater pistons would always dyno better than flat-tops, despite the fact that the flat-tops had more compression. I don't think we talked about M&W pistons. Is that why you aren't using flat-top pistons?
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Posted By: DrAllis
Date Posted: 12 Jul 2024 at 2:55pm
| I've never used flat tops because I always felt Power Crater was better. When I had Ross make me custom pistons I was able to spec the bowl diameters (top and bottom) and bowl depth (cc's) and compression distance (pin to piston top) to exactly what I wanted. So, why not go with the Power Crater design ?? I also have never had the time or money (maybe the other way around) to build an engine with 8.25 to 1 compression flat tops and then tear it apart and install 8.25 to 1 Power Craters from a 175 tractor. I would assume all things being equal (4 inch bore and same compression, same cam, head and carburetor) the Power Craters would show some slight advantage. I would also be willing to bet if the flat tops were at 9.0 to 1 instead of 8.25 to 1, that might be the winner in making the most HP. We will never know. My pulling engine is 4 5/8" plus bore and cranking compression tests at 300 psi with Ross custom made Power Crater pistons. |
Posted By: HudCo
Date Posted: 12 Jul 2024 at 7:29pm
| i told them i wanted the bowls and pin hieght exactly the same on purpose so i can shave what i want , and start with somthing that allready works, i left the ring grooves to them they recomended lighten ing them up and shortening the the skirts some maybe the next go around i will have the recipe changed it took a long time to get done and they were not cheap |
Posted By: DrAllis
Date Posted: 12 Jul 2024 at 7:53pm
| I've always said that using an SP-46 M&W piston that .170" had to be removed from the top of the piston. This was not a way to get the compression where I wanted it. It was necessary to keep the piston from smacking the head !!! The cranking compression will be approximately 240 psi when doing this. Remember, the connecting rods have their limits !! My pulling engine uses stronger rods than the ones you will use, so I can tolerate 300 psi of cranking compression. |
Posted By: steve(ill)
Date Posted: 12 Jul 2024 at 8:52pm
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was the "sample piston" already in an engine ?? If so, and i obviously did not hit the head, then the .170 or so has already been removed and designed into the NEW pistons ? ------------- Like them all, but love the "B"s. |
Posted By: DrAllis
Date Posted: 12 Jul 2024 at 9:56pm
| The sample piston was used in a WC/WD with a 4 inch stroke crank. Not a 4 1/2" stroke crank. |
Posted By: Thymansrepairandcust
Date Posted: 12 Aug 2024 at 12:17pm
| Do you have the specs that you used to get these made from ross. I contacted them but I don't have my motor apart to get the specs needed to get some built. I figure if I take the specs you used and take off the little bit off the top I should be able to drop it right in my motor and be good without having to machine anything else off the top. Or do you have a set that you would sell? Thanks in advance. |
Posted By: Phil48ACWC
Date Posted: 15 Aug 2024 at 5:50am
| I have an original WD 45 Crank Shaft in good shape I would sell. $300 plus shipping. |
Posted By: Larry(OH)
Date Posted: 20 Aug 2024 at 6:46am
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I have a set of AP-46 pistons that shows where they need relief cut for the valves if not milling the top off... LOL ------------- '40 WC puller, '65 770 Ollie *ALLIS EXPRESS contact* I can explain it to you, BUT I cannot understand it for you!! |
Posted By: IBWD MIke
Date Posted: 20 Aug 2024 at 8:40am
I hope not more that four of them!
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Larry(OH) wrote:Posted By: DMiller
Date Posted: 24 Aug 2024 at 10:13am
| Any concerns on these for the Side Reliefs around the Wrist Pin bores Galling or swelling from heat into Cylinder walls? Or have they relieved the Sides to a larger clearance to Sleeves? Had problems years ago with some aftermarket Cummins Pistons that had little to no Wrist pin area relief and would score the Cylinder under High Continuous HP deliveries. |
Posted By: WF owner
Date Posted: 24 Aug 2024 at 3:17pm
| They are, basically, a clone of the M&W pistons that have been used for years. |
Posted By: Ol case mike
Date Posted: 08 Nov 2024 at 3:34pm
| I have a set of 46MW with .170 removed I installed em and have 300 cranking psi should I take more off DR Allis I have started it but only at a idle with race gas at 20* timing hate to blow the rods out the side if it’s to much |
Posted By: DrAllis
Date Posted: 08 Nov 2024 at 3:58pm
| It's been 40 years ago, but i thought mine ran 240 psi cranking compression, maybe 250 psi. I used D-17 conn rods. D-17 and newer rods are a little more stout than an old WC/WD rod. Always used 110 octane fuel or better. Timing was around that 18 to 20 degree BTDC. Did you install new valves?? that were bigger diameter than stock valves ?? That could raise the compression a little. I wouldn't know how much to tell you to remove. It's only the outer edge, not the whole piston top. |
Posted By: Ol case mike
Date Posted: 08 Nov 2024 at 5:40pm
| I put em into a gleaner z code 4-1/8 bore x 4.5 stroke unstyled wc nothing else done to motor except cut off carb flange and welded D-19 carb flange on to it I’ll run it see what happens next season |
Posted By: HudCo
Date Posted: 10 Nov 2024 at 7:31pm
| i welded up my carb flange and milled new holes in for my d19 carb still waiting on my crank and head |