Which fuel rails are interchangeable? S4-S5? N/A- TII. I ask because I am rebuilding a TII motor S4. when I put on the secondary fuel rail, the injectors hover, I may have picked up the wrong rail. I have 3 stripped motors in the shed. One of the S4's I had came with a set of spare rails which I believe are S5.

 

A turbo (s4 or s5) has different rails than an NA,

But they are interchangealbe. as long as you are taking from a turbo to a turbo...

and so on for the NA.

 

so why would my secondaries hover? they don't quite go down all the way.

 

S5 and S4 are not interchangable. The s5's are made of steel and have welded ends as the s4 are made of cast aluminum and are threaded on all ends.

Which ones do you have?

 

I have the welded ones. I had the threaded ones, I can't find them. I wanted to change to the S5 for the FPD. I know it may also leak, but it seems much less likely.

 

S5's do not belong on an s4 period. The s4 fuel rails are an easy and cheap find. Try www.mazdarecycling.com the boneyard, or go onto ebay and check for them. There is also an ebay guy who's i.d. is mrmazda7 he always has the **** i need when i contact him and his prices are good. His name is Curtis.