Bosch 1600cc Injector Modification

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SonicRaT | August 16, 2013 | no comments

Upgrading the secondary injectors is often an early step along any RX-7 build path. It should be no surprise that the Bosch 1600cc injectors are the injector of choice for many at this stage. They offer massive flow at a conveniently low price (anywhere from $50-150 for a set of used injectors in good condition). However, these injectors will not fit the stock rails without modifications. While this process is often spoke about, there has been to this point little documentation of the process.


You will start with something looking similar to this:



The first step will be to remove the top o-ring (already removed in the picture) as well as the lower o-ring, pintle cap, and spacer. Be careful when removing the original caps, they are quite snug and it is very easy to damage the injectors!

This will leave you with the following:



Next comes the trickiest and, perhaps, scariest part. Using a small hacksaw blade, gently cut a circle along the ribs at the top of the injector. On occasion, attempt to twist the plastic rib with a pair of pliers until it breaks free, taking care not to damage the O-ring seats at the top. Then, cut this free piece of plastic out and continue with the remaining ribs. After removing each rib, place a stock rubber gromet onto the injector and check for appropriate sizing. In my case, I had to leave one rib in place. Often times, you will remove them all. Refer to the pictures below:




Once you have the plastic adjusted to size, install a minimum of two o-rings (three is better, but you may have a hard time getting them to fit without cutting the bottom ring). Then, install a new Series 5 pintle cap (You can order a JDM injector rebuild kit on ebay that includes all necessary components). You will want to heat the pintle caps up PRIOR to installation, or you risk cracking the cap. They “snap” into place and take a bit of force. Do NOT push the injector down onto the cap on a surface, as you will damage the needle! Afterwards, install a lower grommet and you are all set.