What is a good set up jets and metering rods for a #7042240 Q-jet on a star wars air cleaner for a 65 Riviera 425 bored over 0.30, ported heads,ported q-jet manifold ala gessler style, ported exhaust manifolds, isky cam dur 270 int. & 280 ex. lift .469 int. & .496 ex. on a 110 LC. , also petronix ignition recurved to a dual quad spec, 3.23 posi switch pitch 400 w/ 300 converter 12'' transo go premium shift kit. Any gurus want to take a stab at this.
By no means a guru and I dont know how you account for cam specs, but I have a 7041304 Q-Jet (66 Service replacement) with a Doc Mod manifold on a stock 65 Gran Sport with 3.23's and a ST-300. Runs 14.76 and gets mid-high teens MPG. It's slightly rich at cruise, I'd probably go back ot a .043 rod. It's set up like this, and follows a pretty standard Cliff Ruggles build....let us know where you wind up! [TABLE="width: 175"] [TR] [TD="class: xl24, width: 154, bgcolor: transparent"]Fuel Inlet [/TD] [TD="class: xl25, width: 78, bgcolor: transparent, align: right"]0.145 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Float Level [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.250 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Idle Tube [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.035 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Idle Channel Restriction [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.046 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Accel Pump Discharge [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.030 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Main Air Bleed (upper) [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.070 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Main Air Bleed (lower) [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.070 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Idle Air Bleed (upper) [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.052 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Idle Air Bleed (lower) [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.060 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Mixture Hole [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.094 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Primary Jets [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.074 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Primary Rods [/TD] [TD="class: xl27, bgcolor: transparent, align: right"]0.042 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary Well restriction [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.032 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary POE Restriction [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.052 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary Tube Restriction [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]0.036 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary Rods [/TD] [TD="class: xl28, bgcolor: transparent"]CK .0527 L [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary Valve Opening [/TD] [TD="class: xl25, bgcolor: transparent, align: right"]1.130 [/TD] [/TR] [TR] [TD="class: xl24, bgcolor: transparent"]Secondary Hanger [/TD] [TD="class: xl26, bgcolor: transparent"]K [/TD] [/TR] [/TABLE]
This works great for me, but this is a different carb than yours - mechanical secondary dash pot, I believe different float geometry, etc...I still think it's a good starting point. Be careful on the lower idle air bleed - I intially opened it up to .070 and the car would stumble badly off idle.... chased it with rods and jets for a whole year. Talked to Cliff, and closed it back up and it's like a whole new car. Funny what kind of difference .010 can make! Good luck!
Leave all the airbleeds stock on that carburetor number. It has an APT system in the baseplate, if you can get the factory APT screw out, it changes everything for jet/rod requirements. We sell an external APT screw, and when used with the correct jets/rod gives the tuner a wide range of control with the APT system. I'd measure the idle tubes and idle down channel restrictions. Most likely it's going to need a slight increase in idle fuel delivery over the stock settings.....Cliff
CT's are fat and short...but they worked better than expected on my 71 (it has the sme carb....for whatever reason) I switched to CK's on that motor too, and I like them better - brings in more secondary fuel and earlier...
my 7042240 came with 73 jets and 48 rods - I kept the jets and used 43 rods and it worked out pretty good, and that was on the 71 455 On my nailhead I have 74 jets and 42 rods - for whatever reason with 44 rods it ran great at cruise, but smelled lean. Like I said, I will probably go back to 43's on that too... Whatever you go with , you want to try to keep the starting relationship about .030 between the jets and rods, and as close to the stock set up as possible......and then find your best volume from there. Here's a good article on primary tuning that helps explain... http://www.corvetteclub.org.uk/files/downloads/how_to_tune_a_qjet.pdf Keep us posted - it's a process, and takes more than one try usually.
"So what jet Size and rods then" With or without using the APT system? I run the stock jets and metering rods if you don't install an external APT screw, and see how it works? Part throttle A/F tuning will require removing the airhorn and changing metering rods at that point. Good idea to install new jets, and make sure the metering rods aren't worn. We throw out the stock parts here, as they are usually worn pretty hard from years of use.....Cliff
Well then Cliff, let me know how much for APT screw and new rods and jets for this set up, of course looking at my set up :star wars air cleaner for a 65 Riviera 425 bored over 0.30, ported heads,ported q-jet manifold ala gessler style, ported exhaust manifolds, isky cam dur 270 int. & 280 ex. lift .469 int. & .496 ex. on a 110 LC. , also petronix ignition recurved to a dual quad spec, 3.23 posi switch pitch 400 w/ 300 converter 12'' transo go premium shift kit.
Our contact info is on the website, we're here 8am-5pm M-F EST: http://www.cliffshighperformance.com/ thanks...Cliff
