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Discussion Starter #1
I am swapping a 1989 4b into my TJ. As some will know the first Gen Cummins B engines, from 89-93 had 9mm injector holes. This led to lots of cracked heads. In 94 they switched to 7mm holes and the p7100 fuel pump. My stock head off the 4b was cracked, so I bought a second hand head from a skid steer, which has the 7mm injector holes. Of course I couldn't get lucky, the injectors were junk. So I bought new 80hp injectors from Industrial Injection, and come to find out the threads on the top of the injector are bigger than my stock ones. So guess what my lines wont work. Did some more research from the local Cummins shop, they make stock replacement injectors for when back in the day the warrantee claims came in, so they are 7mm injectors with the 9mm threads, but as you can imagine its from Cummins so its expensive, and they obviously dont offer a higher performance injector.

suggestions? Custom lines?
 

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I did not know that the 7mm nozzle change corresponds with the larger injection line nuts. I don't have an answer, but I'm interested to see what you find.
 

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In my experience, the p pumps had the larger threads on the injectors. All of my ve injectors took the smaller lines with the smaller nuts. I also found that the cylinder head on my cpl858 has 7mm bores for the injectors to fit into.

As a suggested solution to your dilemma, I would have your injectors rebuilt with 7mm nozzles to be able to fit in the cylinder head that you just got. Make sure to get nozzles with the correct spray pattern- should be 155° for non intercooled with large bowl pistons.

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The rebuilding is probably the best solution. Cummins stopped selling the 9 mm parts some time ago and offered the 7 mm version with the sleeve to fit the 9 mm head. You could use the 5 x .012 marine tips which are 25% bigger than stock and have the 155 deg spray pattern. Probably around $50 ea. You actually don't need anything with more flow than stock unless you're going for a lot of power.
 

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Discussion Starter #5
My whole problem is that I have the 7mm head that is meant for a p pump engine but I have a ve pump engine, so the line nuts are too small for p pump injectors. Will be calling both industrial injection and a diesel shop tomorrow to see about "combining" the old and new style of injectors, wish me luck.
 

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My whole problem is that I have the 7mm head that is meant for a p pump engine but I have a ve pump engine, so the line nuts are too small for p pump injectors. Will be calling both industrial injection and a diesel shop tomorrow to see about "combining" the old and new style of injectors, wish me luck.
Yeah, just swap the nozzles. Use the injector bodies that work with your injector lines and put on 7mm nozzles. Just make sure the spray angle is correct for your pistons. I'm assuming you need 155° spray angle so that would be a dsla155pxxx or dlla155pxxx nozzle.

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I did not know that the 7mm nozzle change corresponds with the larger injection line nuts.
They don't. P-pump and VE-pump injector bodies are different.
 

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They don't. P-pump and VE-pump injector bodies are different.
Ok, so that's the difference, P-Pump injectors have the larger injection line nuts. Thanks for clearing that up :)
 

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Here's the deal the 5.9 in the dodge truck used the 9mm head until they went intercooled in the truck in late 91 production. When the truck received an intercooler it got the 7mm head and a bunch of other changes most people are unaware of.

So when you bought your new injection nozzles you likley didn't give industrial injection enough info and ordered the wrong ones. As far as I can tell the 4bt received the 7 mm head about the same time as its bigger brother. You don't need custom anything, you just need to learn what you have and don't have, and be more careful with a statement like as some may know, when you yourself don't.
 

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Discussion Starter #10
Well after lots of calls to different places and lots of online research, the answer was right under my nose. Here is what I found out.

In 92ish, as previously stated, Cummins changed the injector hole size in their heads. At the same time they also switched to the p-pump. The injectors are very similar but have two slight external differences. The threads for the main fuel lines are bigger, and the tips are smaller. My whole issue was that I had a p-pump style head on a ve-pump engine with no way to put in new injectors.... Or so I thought.

Turns out 90% of the injectors that Industrial Injection sells for first Gen 12v Cummins engines have the 7mm tip, and you have to buy copper adapters if you run them in a 9mm head. So while I though I had to buy injectors for the year head that I have and make them work for the year engine I had, I needed only buy injectors for the year engine and they will work fine.

Industrial injection was very understanding, I sent the originally purchased injectors back, ordered new ones, got a full refund for the first set, and have my very well fitting injectors installed.

Thanks to everyone for all the help.
 

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Do you know what tips you wound up with on the injectors? A stock VE is a 4 x .010 tip with a 155 deg spray pattern. The IC Dodge VE injector is a 6 x .010 but has the 145 deg pattern like the P pump. Many aftermarket injectors use the 5 x .012 marine P pump tip which is 155 deg on the VE injector body. By the way, your head having 7mm holes doesn't necessarily mean it was for a P pump. The 9mm heads started having issues with cracks around the injector holes and Cummins redesigned to the 7mm. There were VE's built with the 7mm.
 

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In 92ish, as previously stated, Cummins changed the injector hole size in their heads. At the same time they also switched to the p-pump. The injectors are very similar but have two slight external differences. The threads for the main fuel lines are bigger, and the tips are smaller. My whole issue was that I had a p-pump style head on a ve-pump engine with no way to put in new injectors.... Or so I thought.


Thanks to everyone for all the help.
This is not accurate at all. Their is no such thing as factory built p-pumped engine in a 1st gen dodge which were built from 1989-1993. The change to the injection nozzle bore also happened in late 1991 not "92ish" like you stated. Their is also no such thing as a p-pump head, an intercooled ve engine has the exact same head as was used on a p-pump engine. So don't beleive everything you read on the web as whatever or wherever you did your research it was not correct.
 

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Get a hold of this guy https://www.facebook.com/RDSPerformance/ he just put up a Facebook page but, has years of experience. Best bet would talk to him and see where your goals are. I'd send injectors and pump to him and have him re-map the timing and set-up the injectors to match. Does very good work and makes really good usable power.
 
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