i have a yaw carb and emailed paul as to what jets to start with on my sp12a with rb header and free flow exhaust. he said to begin with 59 primary and 61 secondary. all was well until i started to order them, and the 59 is actually .058, and the 61, .060. should i go with that, or move up where the jet is actually sized right? sorry if that made no sense.

 

maybe get the .58 .60 and .62

 

Was he referring to jet stamped size or decimal size? It can vary. I dont know what jets he uses in his carbs. And what jets were you ordering?

 

.59mm would be about a .023 inch jet.

He generally keeps the secondary fuel jet down to just below stock and raises the primary into the mid .050s. (The stock secondary jet, 1.60mm = .063 inch, and the stock primary jet .92mm = .036 inch.)

People can easily recognize the need for a fatter primary fuel jet, but go at the recommended size of the secondary fuel jet. That's because they are forgetting that the secondaries are essentially mechanical if the vacuum box diaphragm spring has been removed or untempered, and that the air bleeds are making the necessary corrections.

Generally speaking, plus or minus a thou ain't gonna be that significant unless you are on far more of a cutting edge than most Rx-7s can get as far as consistancy and precision.

 

i ordered holley #59 and #60. does this sound alright?

 

Yeah, to start with.
The fuel jet thread pitch is 10-32. We use Holley Dominator air bleeds for our fuel jets and our emulsion tube air bleeds, but I don't know what sizes are available because I purchase them in bulk and drill my own.