So I am mostly an electics guy, but I never shy away from ICs when they come my way. Nearly all the LPG powered ICs that I ever see have nissan H20 engines with impco model J FPRs, but last week I had a service call on a Mazda powered yale with a bad FPR, it was buzzing and freezing up. I went to replace it with a model J, but found that it had an identical looking cobra FPR. I noticed that the outlet pressure was.2 W.C. as opposed to the.08 W.C. of a model J. More than twice the pressure of a model J (but still not a lot). So I had my parts guy order a "correct" replacement FPR, and what I recieved (from total source) was a cobra with an outlet pressure of.08 W.C.! What could the possible difference be between a model J and cobra with the same outlet pressure? They look identical in every way. Also what does W.C. stand for? water column? why not use psi or bar?

The engine ran good enough with the.08 cobra when I installed it, but I wasted a lot of my customers time and money if the model J would have done the job just as well.