426 camshaft
Printed From: Unofficial Allis
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=195907
Printed Date: 12 Nov 2025 at 2:38pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 426 camshaft
Posted By: SteveM C/IL
Subject: 426 camshaft
Date Posted: 28 Jun 2023 at 10:17am
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Has anyone successfully improved the profile for better performance in the field (farm tractor) ? The valve to piston clearance is tight to begin with and if you start moving opening and closing degrees around you could have interference quickly. Comments?
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Replies:
Posted By: DrAllis
Date Posted: 28 Jun 2023 at 10:46am
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My opinion only: I haven't the time or $$$$$ to experiment with camshaft grinds in a farm tractor. I have to trust the original Engineers were satisfied enough with what they used to have decent performance AND relatively long life from the camshaft, lifters and all the other valve train parts, including valve face and valve seat life. IF one was going to try something, I suppose copying a grind from a 2-valve Cummins 5.9 might be a good guess or 6.7 Cummins if they make a 2-valve version. Always remembering the cylinder heads porting effects what the end results are. I would rather spend my time with better and more efficient turbocharging and exhaust manifolding. An IH DT-400 series exhaust manifold can be grafted onto an AC-426 and the results would be for the better. There sure are on a pulling engine.
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Posted By: SteveM C/IL
Date Posted: 28 Jun 2023 at 9:33pm
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While you mention it,is there a simple bolt on turbo to replace oem T04B that is better? It works OK and shaft it tight enough it won't scrape hsg.
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Posted By: DrAllis
Date Posted: 28 Jun 2023 at 10:27pm
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I'm thinking we are talking an 8000 series turbo?? That version of TO-4B turbo is the last and best A-C ever used and started on the 7080 and then 7580 and all 8000's, 8030 and up. It was matched up pretty well to the engines desired performance RPM curve, spooling up at about 1700 RPM. It moved more air than previous TO-4 turbos used on the 7060 on down. I'm sure there are more modern turbos with or without waste gates that would move more air, but I'm not able to recommend one with confidence. Having a turbo spool up quicker than 1700 RPM in the hands of the wrong operator just places stress on the bottom end of the engine that doesn't have positive results over time. Moving more air with a better exhaust manifold and turbo should clear up some smoke and improve efficiency somewhat. Most modern day engines produce 20 HP per gallon of fuel burned per hour....200 HP flywheel HP at 10 GPH burn rate. Nebraska Test had the 8070 at 10.5 GPH at 171 PTO HP (200-203 flywheel?) @ 2250 engine RPM which is pretty close to that but I'm sure could be improved a little. An M-100 AmBach inj pump with Bosch injectors is about as clean burning as any 426 ever got 40 years ago.
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