Allis 670T timing
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=102982
Printed Date: 17 Jul 2025 at 11:16pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: Allis 670T timing
Posted By: Silveroddo
Subject: Allis 670T timing
Date Posted: 09 Mar 2015 at 6:01pm
Hey Everyone,
I have an early 80's Champion road grader with an Allis 670T motor that I had purchased with known issues. The original theory was that the motor was a repower that had roughly 3500 hours on it, after some brief online research it seemed like it was probably due for Injectors or a pump. The symptoms were lack of power, excessive smoke, and hard starting. Another thing that was suspect was the timing. I previously replaced the injectors and while they were in need of service that didn't correct the problem. Now I've replaced the pump, but am having problems determining correct timing. The Fiat Allis book I have actually has about 4 different timing options depending on the motor and pump. The pump is a roosa master, DM4629JF3865 and my book says to set it at 18 degrees btdc. I tried that and the motor smoked worse than ever. Next I tried 24 degrees and that didn't do anything.
After some reading I came across some info about the damper pulley slipping so I'm heading out to pull the #1 injector and compare the marks to TDC. Aside from than........
Can anyone provide me with a solid # for timing on this pump? Its really leaving me scratching my head on this one.
Any input would be greatly appreciated
Thanks!
j
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Replies:
Posted By: DrAllis
Date Posted: 09 Mar 2015 at 6:17pm
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16 to 18 degrees BTDC would be correct for a DM-4 pump. 24 degrees will make it hammer and start even harder and burn a piston/blow a head gasket.
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Posted By: Adam Stratton
Date Posted: 09 Mar 2015 at 6:36pm
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You can take the valve cover off to confirm the marks on the pulley, that way you know that you are at the top of correct stroke instead of being half way off.
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Posted By: Silveroddo
Date Posted: 09 Mar 2015 at 7:17pm
Thanks for the quick responses, I've got the valve cover off and pulled #1 Injector to verify TDC, seems to be correct. I will have to set it back to 16-18 and see what it does.
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Posted By: SteveM C/IL
Date Posted: 10 Mar 2015 at 12:07pm
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These engines don't burn clean as a rule.There is usually a haze which increases under load.
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Posted By: Silveroddo
Date Posted: 11 Mar 2015 at 9:31pm
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I've got the machine set at 18 degrees, smokes pretty good as its warming up but does seem to run better. Kind of disappointed in how hard starting it is cold though. Would running it around 16 degrees help this? seems like it has to crank for about 30 seconds to get it to pop off at the moment
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Posted By: DrAllis
Date Posted: 11 Mar 2015 at 10:18pm
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16 degrees will help some with cold starts, YES.
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Posted By: SteveM C/IL
Date Posted: 11 Mar 2015 at 10:54pm
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If they're a little tired and it's below 40deg you'll need a heater or ether or extra cranking time.
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