Cummins 4BT & Diesel Conversions Forums banner

1 - 10 of 10 Posts

·
Premium Member
Joined
·
165 Posts
Discussion Starter #1
Ok I bought 6 new injectors online cheap they were returns on amazon they are the 7mm and didn’t come with the sleeves.I didn’t know I needed bought what would fit my engine as far as year or so I thought. Can I swap my 9mm tips onto the 7mm body? I do not want to spend more money on these sleeves. So figured I’d ask before I tear them apart and try it on one I have two spares so won’t hurt my feelings to experiment on 1 new one. Or can I run it with just the copper washers and no sleeves.I read a number of threads online and no one out right said yes or no on swapping the tips and or no sleeves.
 

·
Premium Member
Joined
·
165 Posts
Discussion Starter #2
Well I am supposed to have them with this rebuild kit I bought for the 4bt the bin that they are supposed to be in in my shop I only have one so have to see if the other 3 sleeves are somewhere else in my shop ughh:/
 

·
Registered
Joined
·
1,017 Posts
If you just blindly swap the 9mm tips onto the 7mm bodies the pop pressure of the injectors will be off. Setting the correct pop pressure is key to good injector performance.

Secondly, the tips are the part that wears out so if your 9mm tips are shot then you won't improve anything.

Lastly, the sleeves take up the dead space when installing 7mm tips in a 9mm head. This provides a heat sink to keep the tips cooler and maximizes combustion efficiency.
 

·
Premium Member
Joined
·
165 Posts
Discussion Starter #4
Thank you that definitely gives me a better understanding I will just have to replace the sleeves that got lost one of my chickens got into my shop and flung the bin that had all those parts inside it so will have to buy them again:/
 

·
Registered
Joined
·
11,339 Posts
The 7mm to 9mm sleeves are Cummins part 3919358. They aren't very expensive. Prosource Diesel sells a set of 6 for $17.95. If you get them from Cummins they are probably $7-8 each.
 

·
Premium Member
Joined
·
165 Posts
Discussion Starter #8
Ya I know right also my 16yo son is absolutely terrible about leaving doors open so he got his butt chewed out. I try to teach him to be responsible his job at the end of the day is picking up tools and shutting everything up and locking the doors. I am trying to get him ready for when he enters the workforce so definitely a teaching moment. He’s a hard worker and a very good kid so I think the 15$ I spent yesterday for 6 of those sleeves shipped didn’t hurt as bad because he learned a valuable lesson but that chicken 🍗😁
 

·
Premium Member
Joined
·
165 Posts
Discussion Starter #10
Well I got the injectors installed with the copper sleeves the two that were stuck I made a homemade puller to get out and they were really stuck #1&#4. I just hope the cheap injectors will be ok hopefully my 200hp goal will be within reach. My son and I have definitely been hard at work I just hope I can make all this come together and work.
 
1 - 10 of 10 Posts
Top