8070 ambac pump
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=206961
Printed Date: 06 Jun 2025 at 10:21am
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com
Topic: 8070 ambac pump
Posted By: Gleanermanl2
Subject: 8070 ambac pump
Date Posted: 03 Jun 2025 at 6:16am
Getting the pump and injectors redone on the 82 allis 8070. I read somewhere about the brass tee on the pump needing drilled out from .040 to .052. Is that a true allis update and recommended on my tractor?
Also had some guys talk about setting pop off pressure on injectors to 3600 vs the allis rated 4200. Is that recommended for my tractor?
Anything else I should know while I have the pump at the shop?
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Replies:
Posted By: DrAllis
Date Posted: 03 Jun 2025 at 6:37am
Posted By: Gleanermanl2
Date Posted: 03 Jun 2025 at 12:27pm
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I appreciate you dr allis!
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Posted By: DrAllis
Date Posted: 03 Jun 2025 at 12:42pm
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I'd be surprised if that orifice hasn't been drilled out already. We did a couple dozen of them back in the early-mid 1980's. I made a tool to do it on the engine so pump removal wasn't needed. The lower injector pressure setting will help make the inj pump and injectors last longer and still perform just fine.
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Posted By: Gleanermanl2
Date Posted: 04 Jun 2025 at 11:56am
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Got off the phone with the pump shop today. They said they had never heard of drilling out that orifice and wouldn't do it and stand behind the pump. Thought it was odd. I assume that would have been an allis only update?
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Posted By: DrAllis
Date Posted: 04 Jun 2025 at 12:30pm
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I got the information from an official A-C bulletin probably in late 1982. It was to cure an engine "rattling" noise at certain RPM's. Ed would know if AmBach ever sent out a letter. Have these guys even checked to see what the orifice size is ??? It may be drilled out already.
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Posted By: Gleanermanl2
Date Posted: 04 Jun 2025 at 12:51pm
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He claimed it was still .040. I bought #55 drill bit and I'm going to drill it myself. I was just surprised that this wasn't listed in the updated foot notes for the pump rebuild. He did put a new head in the pump and claimed the introvance had too much backlash. He put new tips on all the injectors as well. My local gleaner dealer says they are the go to shop for these pumps so I'm not real concerned they don't know what their doing but the orifice thing makes me scratch my head a bit. I have read enough of dr allis posts to know you are very knowledgeable but also at the same time I remind myself I am listening to someone I don't know on the internet over the injection pump shop. I consider myself fairly smart and I can tell people who post with knowledge and people who don't know a 1/2 inch wrench from a 13mm. That is why I plan to drill the orifice out. It's kind of scary that without dr allis and his knowledge I don't think I would have ever heard of this! I thank you sir
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Posted By: injpumpEd
Date Posted: 04 Jun 2025 at 1:21pm
That tee is not even an AMBAC part, it's an Allis part. I have the bulletin that discusses the increasing the orifice size. I do it to all the AC M100's I do here, and if they don't come in with the tee, I sell them one, as it is part of the pump calibration. The original hole was .040", and new size is .052", and use a #55 drill bit according to the bulletin. Many shops fail to replace all the orings on the fittings, including the tee.
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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: Lynn Marshall
Date Posted: 04 Jun 2025 at 5:48pm
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I can distinctly remember that particular bulletin too. I may even have a copy myself. It doesn't seem possible that it's been 43 years ago.
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Posted By: Gleanermanl2
Date Posted: 04 Jun 2025 at 8:44pm
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I appreciate all you guys chiming in here. There's a lot of knowledge between the ears of you fellas and I'm so grateful your willing to share it. It makes me wonder if there are other updates I'm unaware of. I wish there was a list I could refer to. I suppose Schmidt and sons in Mt hope would be my best dealer space that might have held onto that information. I should give them a call sometime.
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Posted By: SteveM C/IL
Date Posted: 05 Jun 2025 at 10:09am
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Where is the T? Is it on the back side of "head" which the return runs through? What is this "rattling" from? I bought an 8030 this spring for a planting tractor. At 1200rpm no load it sounds like a precup engine. Haven't taken time to check timing yet but way more rattle than my 8070's with A pumps @ 32deg.
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Posted By: DrAllis
Date Posted: 05 Jun 2025 at 10:20am
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On the backside of the inj pumps hydraulic head towards the engine block. Return fuel from the injectors goes in the front of the tee and all return fuel (and air) goes to the fuel tank out the rear of the tee. I made a 9 inch long deep 9/16" socket to remove the rear return line and could (not easy) remove that tee without removing and re-timing the injection pump. That's what they do.....rattle like crazy from too much air in the fuel around the hydraulic head. Not to be confused with the AmBach governor quiver at certain slower engine speeds. Two different problems.
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Posted By: DougG
Date Posted: 05 Jun 2025 at 10:29am
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So just curious - why did Allis go to Ambac at that time?? Wasnt Standyne/ Roosamaster still in business??
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Posted By: DrAllis
Date Posted: 05 Jun 2025 at 11:16am
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Better cold starting. Less smoke when working in the field. I don't know about the cost difference. I've felt for 35+ years the AmBach pump was harder on the engine (head gaskets, etc) because of the beginning of injection always being the same versus the RoosaMaster being variable beginning of injection. Just listen to an 8050 running right alongside a 7060 and the hammering is obvious on the 8000 engine.
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Posted By: DougG
Date Posted: 05 Jun 2025 at 11:19am
Posted By: SteveM C/IL
Date Posted: 05 Jun 2025 at 8:29pm
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I suppose the hole is in the part that screws into pump not the straight through part where return lines attatch so it must be removed. Uh,is the rattle harmful or just sound that way?
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Posted By: DrAllis
Date Posted: 05 Jun 2025 at 8:35pm
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The tee with the orifice built into it has to be removed to be able to drill it out. When you see where it is, there's no room. The engine sounds like absolute crap when you don't do this. Can't be good for things.
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Posted By: SteveM C/IL
Date Posted: 05 Jun 2025 at 8:46pm
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You are so correct on location. Could be enough fun just removing let alone reinstalling.
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Posted By: DrAllis
Date Posted: 05 Jun 2025 at 8:52pm
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I think the first few I did there were some new cuss words created............
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Posted By: Lynn Marshall
Date Posted: 06 Jun 2025 at 7:14am
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Been there, done that. Certainly not the worst Allis project that I've been involved with.
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