sethjohnson71

I'm rebuilding the q-jet on my 74 and just wanted some advice on what rods/jets to go with for max performance. The carb is #7044206, has 75c jets, 46b primary rods, and secondary rods that have two stamps each, CG and CC. The CC marking appears to be stamped over the CG, so I think CC is the size.

The engine the carb is on is 9-9.5:1 compression 350, Comp XE262 cam, 64cc heads, weiand action plus intake, flamethrower module and coil. Oh yeah, the car is an auto.

Also, what should I set the float to? Is .420" correct for this carb?


Thanks in advance!

jotto

Lars will chime in and help...sounds about right and Im sure Lars says to set float at .420" so that part is at least correct.

BigBlockk

To get the most out of the car you're going to have to tune it. We really can't give you a magic number of jet/rod. You will need to make timed runs to see what your car likes most. Get yourself a cheap air/fuel ratio meter as a guide.

http://egauges.com/vdo_mult3.asp?Typ...ries=Cyber_Red

The resolution isn't the greatest but it will alert you if the mixture does something stupid. Just find a section of road where you can accelerate from 40 to 70 MPH (level on ramps are a good spot) and time the car after each change. Lock the secondaries out at first so you can concentrate on the primaries.

BigBlockk

Later.....

Kalway

That guage doesn't come with an o2 sensor, though, does it?

BigBlockk

No it doesn't but it will work with stock '80's single wire units.

BigBlockk

Later.....

74ZZ430

I also have a 74 with the same carb number as you, I'm using it with a copy of a ZZ430 motor. 76 primary jets worked well for me until I took the choke plate out then I used 77s so the the car ran better cold without a choke. I tried a lot of secondary rods and I beleive the DAs gave me my best times. I going to be purchasing the NGK wideband oxygen sensor kit shortly,to do some more fine tuning.

sethjohnson71

I've ordered some different sized jets/rods to play around with, but I think I'll put it back together with what I had to begin with so I can get a baseline for performance and then I'll switch in some different combos.

thanks for the help so far guys!

lars

You want to set the float level to .375" for that carb. The 1975+ carbs get the .420" float level. Make sure your float is a new NAPA part number 2-440 NitroFill float.

Your 75/46 jet/rod combo is not bad, but with your parts selection, I would bump the jet size up just one size to make it a 76/46. The CH sec rods should work well, but if you install headers or open up the exhaust you can swap in a slightly richer set.

Make sure you set up your total timing to 36 degrees before doing any carb tuning work. From this baseline, you can then determine what else the car wants.

sethjohnson71

Lars,

Thanks for clarifying on the float setting. I forgot to mention that I do have a 2.5" dual exhaust system in place already. I ordered DA secondary rods and 76 jets. Thanks for the help!