I got a set of nismo 555 (purple) for 90 model 300zx, but looking at the photos of stock ones 370cc they look the same. Whats some physical difference to differentiate the two? cheers
No physical difference between Nissan/Nismo...... because the "type" of injector is the same. The injectors sizes are identified by the colour on the top, the original oem injectors had a dark brown top. If you use the "search" function you're bound to find some posts detailing colour vs size.
What of they are both coloured the same though? The ones i bought were told to be 555 nismos and used. Purple tops and the bottoms have turned orangish?
exposed top's of the 555's turn an orangish brown colour over time due to heat and that looks almost the same as the stock injectors do over time. If the covers parts of the cap are purple, then they are likely 555's, but as with all 2nd hand injectors, get them professionally cleaned and flow tested at the same time.
Yeah asnew use orange pintle caps like j4play said,after they clean your injectors. There the orange things on the bottom of the injectors.