So Ive got an LSXRT on my 5.3. Its been a long build and swap but its finally together. Im having an issue with with my injectors leaking at the fuel rail. I had bought some budget rails from nasty performance and made some hold downs at work but they dont seem to be compatible with the manifold.

Im not sure if my hold downs are the problem, or if the rail is just not the best quality or what. So I decided to eliminate my headache and just go with the rails and hold downs from FAST for the lsxrt. Except the brackets are designed around the shorter LS2/truck injector. Im currently using a 42lb LS1/LS6 style injectors.

Ive tried everything I can. Shimming the rail, new orings on top presoaked in lucas injector cleaner (aka oil). Now I thought buying the FAST rails would make everything plug and play but not so much.

Im just curious if anyone out there is successfully running LS1/LS6 height injectors on this manifold.

 

I am also curious about this.

 

Nope, I ended up with LS2 injectors with mine. You should be able to use spacers though and everything will work just fine with the correct upper o-ring. There's no reason it won't.

 

Here's the thing though. Injectors are angled. Therefore if you increase the height it moves the mounting holes further away horizontally. I'm going to attempt to make some spacers and hope that this change is negligible. Either way you have to either space the bracket and slot the lower hole or space the bracket and push the rail changing the angle slightly and possibly still causing a fuel leak.

I'll report back when the fast rails come wed. I really think its just the cheap rails I have.

 

https://ls1tech.com/forums/fueling-i...injectors.html

You also need to use the thicker o rings fast supplies with a new intake, or buy a set.

 

Yeah that I know. I don't have any issues with the body of the injector being anywhere near the manifold.

 

10-4. The fast rails cant the injectors so I think that may cure your issue. You said the nasty rails try to keep them strait up and down correct?

 

Can the brackets on the truck rail be slotted or additional pieces be welded on? OP, do you have any pics?

 

Stomis, you still alive?

 

No not straight up and down but the fitment on the upper end of the injector just doesnt seem right.

I will update when I have them on this weekend and I'll include whatever I did with spacers etc to make them work.

When I got the rails they did have small spacers with the brackets but I suspect these are for the LS3 vs LS2 length difference.

 

So by no means is this a bolt a spacer on affair. My suspicion about the injector angle and drastic length difference between the truck and EV1 injectors moving the mounts holes was correct. Math and angles and such, who woulda thought right?

So the problem isnt resolved, yet. I had a crazy week working two jobs and crazy hours etc so Im kinda pooped. I did pull the old pass side rail off and start looking at the problem. Heres what you get with the EV1 injectors, sitting at their natural angle and the brackets properly installed on the rail.






Clearly no amount of slotting in the world will solve that. Sure you could make new hold down brackets, but the angle of the bend is very crucial and CNC bent, ive been down this road with the old rails as I said and to be honest Im planning on devising a very simple kit that will allow the "stock" fast brackets to be used with these injectors. Im thinking something in the ballpark of a $20-$30 hardware kit basically just to provide an answer and help the community out with this issue. Theres nothing I hate more than punching a compatibility question into the world wide web and getting NOTHING back lol.


So I have plenty at my disposal. Small 3in1 lathe/mill at home, CNC mill at work, decent size lathe, plasma table etc etc. So I will solve this problem and report back.

My first thought was to flip the brackets on the fuel rail like so...





This would allow some minor slotting and the use of a .600 spacer but I mean honestly do you want to countersink the other side of your brand new $250 anodized FAST rails??? I know I dont...

So now Im gonna sit down on Mcmaster and come up with a hardware list. The idea is to basically make a .25 thick plate that will bolt to the factory hold down location but also be offset and threaded to step back to where the FAST bracket lands with the new injector height. No modification will be required to the bracket, rail, or manifold this way. Plus if you wanted to switch to a shorter injector down the road your brackets arent butchered and you can just uninstall said relocation kit.

So thats what Ive got for now. Report back with some progress this week.

 

So heres what I came up with. In all honesty a full replacement bracket would be better.





Measurements were good because they fit perfect. The lower bolts to the manifold will need button heads and the upper bolts are going to need some standard hex head bolt so they can be tightened with a wrench.

 

So theyre a pain in the *** but they do work.

 

Nice job figuring it out! Mind making some of those adapters for me? Send me some payment info!

 

I wanted to bump this up... on my upcoming Hombre swap, I really didn't want to buy LS2 style 42# injectors when mine were in perfectly good shape. So I ran into the issue that Stomis had. Unfortunately he couldn't get back to me, so I went and mocked up the goods. Sure enough, 0.600" is the height difference and the natural angle of the injectors would have the mounting bolt off by a critical fraction of an inch.

I drew up a sketch and sent it to a machine shop, and I have enough material coming to make about 10 sets of four spacers. Depending on the interest, I might be able to put some o-rings and spacers together for some members with this issue. Anyone interested?

I'll get pictures of the first set when he cuts them...

 

Done and working, way behind on updating this! I have a sales thread, take a look...

 

I was asked about the drawing for these spacers, since I sold all my adapters. Here it is, I think I ended up having the shop shave 0.060" from the height of the whole thing for 0.540" (rather than 0.600") but didn't record it. If you bring a stick of 1"x1" aluminum to a local machine shop, they should be able to cut little blocks and get it knocked out without any welding. Hope this helps someone.

 

Whoa! 3 years, but hey, better now than never! lol

 

Yeah, I'd sold all 10 sets and a guy asked for the drawing. So... still relevant I guess lol

 

Are the spacers still available to order ?

Would they work with an LQ4 with the FAST LSXT intake manifold and Fast fuel rails. Since i am getting very bad fuel leaks where the upper fuel injector O-rings seat to the Fast fuel rail.

Thanks