670T engine question
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=209250
Printed Date: 04 Feb 2026 at 6:52am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 670T engine question
Posted By: 8070nc
Subject: 670T engine question
Date Posted: 06 Dec 2025 at 6:22pm
Did all 670Ts with bosch injectors have the large wrist pins
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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Replies:
Posted By: DrAllis
Date Posted: 06 Dec 2025 at 6:45pm
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1982 was M-100 and Bosch nozzles and big pins in the 8000 series and N-series combines for sure. I think the big pin/3-ring piston thing was the fall of 1980 production?? Still a Roosa pump but Bosch injectors. It would have been at a certain eng s/n break. That's kind of how I remember it.
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Posted By: 8070nc
Date Posted: 06 Dec 2025 at 8:06pm
Thanks Doc. The reason i ask is I have a 8070 that has the most blowby ive ever seen. Ive found a 670t thats affordable. I know it doesnt have the counterbalanced crank but no harder than ill use the tractor i think itll be fine. Just have to keep the rpm down to 670t level. It has bosch injectors but no injectoin pump is gone and they cut the injection lines. The stubs appear to have been to a m100 pump
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
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Posted By: Lynn Marshall
Date Posted: 07 Dec 2025 at 7:45am
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Are the pump drive gear and the idler gear still in it? They are different from the M100 to the Rossa. As for blowby, I should have mentioned in the 7010 post, when these engines get coolant in the oil, they will develop what appears to be an extreme amount of blowby. The coolant will pool a little bit on the top of the head,under the rockers arms. As the temperature rises in the engine, this coolant tends to evaporate and causes a steam. When the steam comes out of the breather tube, you would swear that the rings are totally shot on the pistons. The engine may run just fine, but it sure doesn't look like it should.
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Posted By: 8070nc
Date Posted: 07 Dec 2025 at 8:34am
I appreciate your insight Lynn. Its blowby on the 8070. Wierd thing is its the best sounding 426 iv got out of 5. I could build it but ive got too many projects and theres only me now. Things are not like they used to. I cant find anybody to even pick up tools and them do it with any organization
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
|
Posted By: Lynn Marshall
Date Posted: 07 Dec 2025 at 10:02am
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I would somewhat expect excessive blowby to include harder starting and increased oil consumption to be included. In the end, it doesn't really matter if the engine needs overhauled because of poor ring seal or water in the oil. It will still have to be torn all apart.
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Posted By: injpumpEd
Date Posted: 07 Dec 2025 at 2:02pm
For a collector tractor, I would not worry about blowby if it's not drinking oil, and starts good. Those 2 things tell me more about an engine's condition than the smoke out the lower pipe lol! Sometimes when you open pandora's box, you can't close it lmao!
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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Posted By: 8070nc
Date Posted: 07 Dec 2025 at 2:47pm
Ed its not a collector tractor. I use all my equipment. You more than likely you have never seen this kind of blowby. Ive got a 60 by150 shop. If i start it inside in 5 minutes you cant see from one end to the other. Compression is down as it has to spin to start. The main reason i want to change the motor is i want to save that counter balanced crank. Ill put a temporary motir in it so i can build the original back like it should be
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1984 80780
1957 D14
DES 300 with 25000 engine
616 tractor
|
Posted By: injpumpEd
Date Posted: 07 Dec 2025 at 3:28pm
Then it'd be a good idea. Save it before it lets go lol!
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210 "too hot to farm" puller, part of the "insane pumpkin posse". Owner of Guenther Heritage Diesel, specializing in fuel injection systems on heritage era tractors. stock rebuilds to all out pullers!
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