hey guys, I have a pretty good running q-jet.. its a matching number carb. for my 68 396 nova ss..been rebuilt and worked on , by pretty knowledgeable guys.. idle well.runs good.. only problem on WOT its running very rich.. I have an air fuel ratio gauge in car.. its stops at 10.0 on the afr..and that's where it hit under WOT.. I tried leaner rear rods and hangers.. but its still gets to 10.0 on afr.. pretty sure its right.. because it loads up at the end of dragstrip when I take it there..any help is greatly appreciated. thanks,chris
Assuming your secondary air valves and throttle plates are opening and working correctly, it's difficult to say without opening it up. I've seen some pretty stupid things done by people who claimed to be experts. first thing I'd want to know is that the fixed secondary jets have not been messed with.
What jets, primary rods and secondary rods are you using? What hanger? Should have originally had something like 71 jets, 45B rods and AX secondary.
close. 71 jets . 45 primary...ive tried AX rear rods.but , it too rich in high gear and fouls out the plugs...it has a AN rear rod.. which is about as lean as made..and the leanest V hangers.. and its still is rich , with a 11;8 AFR a WOT?
You must have something else going on for your issue. What is your fuel pressure at WOT? Verify with gauge while WOT.
Sounds as if it is flooding. Maybe fuel pressure/float level issue. I know the early Q-jets had a weak float design that really wasn't tolerant of fuel pressure in excess of 6 psi or so. My Q-jet is a 1972 7042240. It easily deals with 9-10 psi. See post #6 in this thread, http://www.v8buick.com/showthread.p...o-during-acceleration&highlight=fuel+pressure
I believe your right guys, had a fuelpump go bad. and put a new carter street pump on it. need to hook up my fuel pressure gauge back on the car.. im betting its too much fuel pressure at WOT.. have a good ac pump. I can put back on it
Or, have one of the 2 guys on this board build you a later model Q-jet that will handle the pressure.
I agree with Mark, there is a "fundamental" issue with the carb not related to the tuning parts being used. I'm not a fan of the early float design for any serious high performance use, but they are fine to about 450hp or so with adequate fuel delivery. That carb should be using the large nitrophyl float and seat no larger than .135" combined with no more than about 6psi fuel pressure. Not following those specs can result in pretty rich A/F at full throttle, intermittent flooding, and driveability issues as well......Cliff
