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AC HD4 Injectors

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=170495
Printed Date: 21 Aug 2025 at 4:09am
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Topic: AC HD4 Injectors

Posted By: johnP
Subject: AC HD4 Injectors
Date Posted: 24 Apr 2020 at 9:02am

Can anyone point me toward a set of injector nozzles for the hd4 d2200 engine. I had my injection pump rebuilt and injectors looked at and they told me I nedd to replace nozzle end. Can I buy these without changing injector? Also there seems to be missing something to hold the injectors strait in the hole. I have some seepage and bubbling coming from around injector body. Any info would be much appreciated.

Replies:

Posted By: Coke-in-MN
Date Posted: 24 Apr 2020 at 10:37am

Any diesel service garage should be able to test injectors , know i had the pump on my HD4 checked out at a Farm service garage locally who was a AC dealer but now Massy
Had couple injectors that also bubbled around interface with head - never did fix them but believe a copper sealing washer is used there .
The pump on the 2200 can be turned up so the engine puts out 85 HP I was told by a diesel shop down in Ill - guy there said he used the engine in a pulling tractor he built and found out Allis used the same engine in cotton pickers but upped the HP when in service in them so he just set those specs and then tweaked it a little further

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Life lesson: If you’re being chased by a lion, you’re on a horse, to the left of you is a giraffe and on the right is a unicorn, what do you do? You stop drinking and get off the carousel.

Posted By: johnP
Date Posted: 24 Apr 2020 at 12:56pm

Ya the copper washers were new when reinstalled injector. Missing something to keep it strait in the hole, also had my injsectors tested when pump was rebuilt and shop told me the nozzles needed replacement. The nozzzle unscrews from injector as far as I could tell. I need 4 better tips or nozzles. And I never got the part# when injector was out.

Does anybody know when some could be had?

Posted By: DMiller
Date Posted: 24 Apr 2020 at 1:17pm

There is a special reamer to reset the seat in the head for the Nozzle Coppers to seat against. Did you remove all the carbon buildup at the bottom of the bore? The nozzle tip has a clearance to the bottom bore hole so does not become constricted when head heats up, that allows a slight amount of carbon to collect there. The Nozzle body is not ever tight in the head bore or once heated up would not ever be removable.

Posted By: johnP
Date Posted: 24 Apr 2020 at 3:52pm

There is 40 or 50 thou on either side of injector and when you thread nuts down on studs it can pull injector either way causing it to bubble abit. As far as the nozzles they are wore out and dont spray properly but do unthread so was hoping to replace.

Posted By: 615_259
Date Posted: 25 Apr 2020 at 6:09pm

Just went thru this with my 615 backhoe with the D2200 motor

the nozzles went thru many part # changes-

got this response from a member

74022900 changed to the thickwall 74007218 same holder as 2800

74020510 changed to the thickwall 74007218 as well same size hole tip...

AC changed #'s a bunch using up nozzles and superseding them to the thick wall tips.

The 218's were for natural aspirated - the later 044 tips were for 2900's and the 74035509 were the higest flow tips for the 7080 -3750 670I etc -- all will interchange in the holders

. the latest part # for these nozzles is 74007218-