Any tips to get the primary injectors to seat a lil better. I took my intakes apart to repair a leaking lower intake gasket and o ring. Putting the engine back together the primary injectors seem slightly loose, like I can jiggle them up and down a bit when I have the fuel rain fully tighten down.

From previous testing I had a slight vac leak at this spot at this location before I took it all apart. I used compressed air pumped through the turbo/intake and air would escape here so its not a new issue but something I want to address while its all apart.

I'm using s5 block, RC injectors 750cc, with a s5 fuel rail, s5 LIM and s6 UIM.

 

I just had this happen, for me, I forgot to install the diffusers. They are spendy, and there is a debate if you need them or not. I chose to put them in. You can buy a spacer to put in if you chose to skip the diffusers.

 

I have both the stock injector diffusers installed and I also purchased aftermarket spacer o ring pieces at some point last year, haven't installed them. I was really nervous about trying to pull those stock diffusers out since their brittle plastic and if they fall apart its all ends up in the engine.

 

I have those same injectors. They are just slightly shorter than the stock ones. The other issues are trying to get a good o-ring seal on the top (I have had blowouts with the ones they came with). Another problem is the notch on the bottom of the injectors around where the pintle caps are on the stock ones. When you put these into the rubber grommets, the grommets get to sag inwards and cause your vacuum problems like you said. I ended up making some sleeves to fill these slots and keep the rubber grommets pushed out. I'll try to take some pictures if I get a chance tomorrow.

 

interesting. I don't have an issue sealing at the top fortunately. They are really solidly set in the top. I drove the car like this for a really long time without issue. But fuel scares me here and since I have it apart maybe I could improve it.

I was considering just bending the mounting location angl eso the top sits lower and closer to the block.

 

HDPE sleeve I made for the bottom notch. It was thin enough that I could press it on and it shrank back snug against the injector.

This picture shows how the sleeve keeps the rubber grommet pushed out evenly instead of letting it sag inwards.

Top O-ring is from a kit. Bottom is the one sent with the injector.

A couple extra thoughts. I remembered that I had issues with vac/boost leaks when I used the rubber grommets from O'Reilly's/Autozone/Take your pick. I ordered a bunch of the original grommets from Mazdatrix and found that they were a few thousandths thicker both in height and radius. They seal a lot better.

I am not very fond of the two o-ring setup I've been getting by with. It has held better than the skinny o-rings the injector shipped with, but I would rather find a better seal for the top, either a fat o-ring I can squeeze in there, or a square profile seal to fit the groove better. I'm sure somebody on here would have a good recommendation.

 

Thanks for sharing the pictures. How you make the HPDE sleeve? That sounds like a solid solution. Were you able to test for vac leaks after installing this

 

I had some mangled up deck rollers that broke off my mower. I cut one up into chunks and turned it down with my lathe. The problem with cutting it was that you had to take shallow cuts otherwise it would just grab a whole wad on the part and start peeling it apart. Drilled it first and put a steel rod down the middle for support. Then cut the OD. It was pretty thin. I didn't need to use a parting tool, just cut it with a knife. It looked kinda like a straw, and I just slid it over the ends of the injectors and used a razor blade to trim the bottom edge flush around the injector tip.

It managed to solve the leaks at that location. I also keep half a dozen of the Mazda grommets in a drawer, because they are just enough thicker that it made the difference for me.