426 compression ratio

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   This is a mental experiment and i should probally quit thinking so much. I have a  DTA 466 with a p pump in a medium truck. It will start in 20 degree weather like its summer. Its my understanding that those engines are 17to one compression. Would it be possible to have a set of pistons made for a 426 allis to raise the compression and what problems could that solve ir create

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8070nc Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 21 Mar 2019 Location: North Carolina Points: 682	Post Options Post Reply Quote 8070nc Report Post Thanks(0) Quote Reply Topic: 426 compression ratio Posted: 13 hours 15 minutes ago at 9:55am
	This is a mental experiment and i should probally quit thinking so much. I have a DTA 466 with a p pump in a medium truck. It will start in 20 degree weather like its summer. Its my understanding that those engines are 17to one compression. Would it be possible to have a set of pistons made for a 426 allis to raise the compression and what problems could that solve ir create
	1984 80780 1957 D14 DES 300 with 25000 engine 616 tractor

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DrAllis Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Points: 22438	Post Options Post Reply Quote DrAllis Report Post Thanks(0) Quote Reply Posted: 12 hours 7 minutes ago at 11:03am
	I'm sure you could have custom pistons made with a few less cc's in the bowl, raising the compression to improve cold starting. Higher compression ratios are harder on the crankshaft, conn rods and all bearings. If you took two identical engines (except 16 to 1 and 17 to 1) and loaded them at 100% load until something failed, the 16 to 1 will run more hrs. it's a compromise. To get one thing, you might have to give up something else. DT-400 series have larger diameter mains and rods bearings. M & W piston kits from years ago did start as good as an IH and some on here can attest to that. Don't think you can buy them anymore.

NEVER green Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 28 Feb 2013 Location: MN. Points: 9042	Post Options Post Reply Quote NEVER green Report Post Thanks(0) Quote Reply Posted: 7 hours 35 minutes ago at 3:35pm
	Throw in some total seal gapless second rings and bam!!
	2-8050 1-7080 6080 D-19 modelE & A 7040 R50

Kevin in WA Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 08 Feb 2010 Location: Lynden, WA Points: 613	Post Options Post Reply Quote Kevin in WA Report Post Thanks(0) Quote Reply Posted: 2 hours 48 minutes ago at 8:22pm
	The M and W pistons for the 426 were the same CR as the stock pistons but started so much better because of a better seal at cranking speeds, and less drag which allowed them to spin faster, wish they were still available... The M and Ws for the 301 were slightly higher at 16.3 instead of 16.25 or 15.5 in the 200 and up

Lynn Marshall Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 13 Sep 2009 Location: Dana, Iowa Points: 2450	Post Options Post Reply Quote Lynn Marshall Report Post Thanks(0) Quote Reply Posted: 1 hour 28 minutes ago at 9:42pm
	It's been a long time, but didn't M&W offer two different sets for the 426? A standard set with a normal ring configuration and then another that had the top ring very close to the top of the piston. Were they an SP 426 or maybe called a total seal kit? I remember that top ring was special in design and was supposed to expand against the cylinder wall tighter as the power was applied. They certainly did improve starting and had practically zero blow by. I don't know if they were ever available for the big wrist pin engines.

SteveM C/IL Members Profile Send Private Message Find Members Posts Add to Buddy List Orange Level Access Joined: 12 Sep 2009 Location: Shelbyville IL Points: 8787	Post Options Post Reply Quote SteveM C/IL Report Post Thanks(0) Quote Reply Posted: 1 hour 19 minutes ago at 9:51pm
	Yes they were. Got a set in 220 and 8070. That top ring is a 90 deg cross section like angle iron and open to the top so compression forces it against liner. Top of ring is flush with piston top. Think it's called "headland"ring. It travels to top of bore...leaves no ridge. Edited by SteveM C/IL - 1 hour 18 minutes ago at 9:52pm