I purchased a radium fuel rail for my build seeing that it basically has no negative reviews, however, mine unexplainably doesn't seem to fit.

When bolted up to the engine (NB head, using bottom holes) the top injector seats bottom out earlier than on the stock rail and cause the rail to sit further off the head than stock and have extra space where the OEM spacers go. I've double checked that all 4 injectors are properly seated top and bottom, put the OEM fuel rail back on to verify (fit just fine), and checked the radium fuel rails injector seat depth vs the OEM rail and it's shallower.

Given the extra spacing where the spacers go, if I try to put any torque on the rail bolts, it tilts the rail off perpendicular to the injectors and all 4 leak badly from the top injector seats.

Has nobody else run into this? I'm not seeing how this could be something I'm messing up, but nobody else seems to have any issues

 

Better picture, but that's about an additional spacers worth of gap with everything else seated. Giving radium a call tomorrow if nobody has any feedback before then

 

Are you using vaseline or oil on the o-rings to make sure the injectors are seated all the way in to the rail first, and then installing it? Have you tried the alternate rail bolt holes to see if it fits better?

 

Yes, seals were lubed and I could see/feel them fully sealed on top and bottom. I did try the top mounting hole but they had an even larger gap and put the injectors at a worse angle which makes sense since those are for an NA head.

Radium actually picked up the phone after hours and after looking at the pics just told me "they can't recommend aftermarket injectors, only OEM size". They might have a point, but if my ID1000s with Miata tophats fit fine with the OEM rail, there's shouldn't be any issues with radium's rail, right?

 

Keep investigating. I’ve got a radium rail and ID1050x and it fits fine. Note that there’s nothing miata attached to my injectors. They are fitted as delivered by ID.

 

That would be the typical answer any aftermarket parts provider gives you.

 

@EO2K didn't we have to mod your radium rail a million years ago? I looked but you post to much for me to find it.

 

For clarification, I got these injectors second-hand and had them cleaned/tested, but they are legitimate ID1000s with the Miata-specific tophats. I gave ID a call and they verified the correct injector measurements and stated "they should be oem height" but I have yet to get my hands on an OEM injector or measurements to compare. They also noted they were the same length as ID1050x's so I'm pretty lost as to where my issue is. Radium rail was purchased new 2 months back.

Regardless of where the issue is, Im assuming the best solution is just to find a way to 3D print taller spacers once I figure out the additional spacing needed. Still frustrating since I thought I was using plug n play parts.

 

It was an M-Tuned Rail but yes, you were kind enough to modify it for me on your fancy milling machine :^)

In fact, I still have it!






As you can see, I used the holes closer to the rail and injectors were ID1000s. If you'd like, I can slap this all together on a head and take pics of the clearances.

Protip: Buy or make an extra set of those spacers and epoxy those ******* spacers to the rail. lolol

Either Radium designed their rail the same way M-Tuned did, or they used an M-Tuned for "inspiration" when designing their own. Hell, maybe they bought the prints after M-Tuned closed up shop. Either way, this isn't a unique issue and I'm not convinced the height of the Injector Dynamics injectors is at fault here.

 

Interesting information here: https://www.miataturbo.net/diy-turbo...-solved-68539/

FWIW my set of ID1000s don't have the extra grommet/ring/whatever they are talking about in that thread

Mine for reference:

 

I have a Radium rail on an NB2 head with FF650 injectors and had no fitment issues.

 

Did you use the holes closest to or furthest from the rail when you mounted it to the 6D head?

With my M-Tuned +IDs, mounting to my 4W head using the outer holes (the only ones that lined up with a bolt hole before it was modified due to the same valve cover clearance issue) resulted in the injectors being cocked at a goofy angle and a torrential fuel leak. Modification of the rail allowed me to use the inner holes, factory rail spacers and resulted in no leaks.

I was using this on a BP4W, and it appears OP is as well if his signature is to be believed. I have both 4W and 6D in my garage at the moment, along with NB1 red, NB2 purple and ID1k injectors, 4W & 6D stock rails and of course the previously pictured M-Tuned rail. I'm happy to measure things if it'll help

 

I'd also like to point out that Radium themselves say to use the inner holes with their rail on their product page.

Fuel Rail, Mazda 1.8L BP

This was physically impossible with my M-Tuned, I literally couldn't get the rail mounting ears flat against the OE spacers even without injectors installed.

 

Well, this sure has me baffled but lots of good reference material.

ID only had the interior upper to lower seal measurement which actually was about 2mm shorter than mine (didn't explain the ~6mm gap), but here's one of my injectors for reference.

The most relevant measurement would be from the bottom of the seating surface to the top of the injector, which came out to 73mm for me.





Im annoyed I hadn't thought of the epoxy before. Im sure we've both spent enough time searching for dropped spacers after you breathe on them and they fall out... The radium rail design seems very similar to M-Tuned but they've adjusted the design to clear the head when using the bottom bolts.

Im running a BP4W and the inside bolt holes seem to line up. If you could grab the pictured "bottom seat to top" measurement from the reds, purples, and ID1000s, that would help me rule out or confirm injector height as my issue. Much appreciated!

 

I used the holes indicated in the diagram you linked above.

 

I also had zero fitment issues with grams 750s. It fits just like the OEM rail.

 

I don't think any of the injector dimensions are a factor here. Also, you'll probably want to measure that injector from the sealing shoulder to the top, don't include the lower seal or the tip.




This measurement isn't accurate with this tool as you are forced to tilt the injector over to get it on the caliper jaw. A better way to do it would be with a height gauge on a surface plate, but I have neither, and this is probably close enough for the sake of argument.

The radius on the ID adapter however...



It fully bottoms out in both my M-Tuned rail and the stock rail. The problem is I DON'T KNOW IF THIS ACTUALLY MATTERS.

You would want to check the distance between the rail spacer where it contacts the head and the sealing "shoulder" on the injector, but again, same applies as above about the surface plate and height gauge. I simply don't have the tools to properly measure this distance.

But going back to what I said previously, if you can't get the rail to even bolt down on the inner hose without the mounting ears hitting the valve cover, the rest of this is purely academic.



@Jumpster74 When installed per Radium's instructions, does your rail bolt down square without the injectors?

As you can see from the above pic, my M-Tuned absolutely would not. FWIW this is the M-Tuned on a BP6D but I had the exact same issue on my BP4W. Again, without injectors installed.

The only thing I can think of that might account for this is some production variation in the gasket flange thickness on the edge of the valve cover, additional variation in the non critical radius on that section of the outside of the cover, stacked up with different thicknesses of valve cover gasket.

After my last statement, I'd like to point out that it appears OP is not using a Miata valve cover.

 

Yes, he's using a escort GT cover that could definitely be the issue.

 

Looks like you'd need additional rail spacers about the width of the lower injector cushion, at least according to E02K's pic there.

The actual measurement you want is cushion to cushion on the stock injectors, and then cushion to radius on the top adapters. If they aren't the same it's not going to work.

All assuming you aren't crashing the rail ears into the valve cover. Seems Radium has fixed the oversight of Mtuned, the ears come pre-notched.

 

I was not aware of this. Got a pic?

Edit: Oh yeah, hah! You can just baaaaarely see it in OPs pics