7045281 RICH IDLE / LEAN WOT

[Mikecaterina]

Im having 2 issues with my QJET (REBUILT AS BELOW)
1st problem is I can't lean idle out enough, stinks of fuel, people complain cover their noses etc. Black sooty tail pipes and spark plugs at idle, NOT wet at all, no nozzle drip.
Not running on transition slot, showing under 0.010" exposed. 

2nd problem seems to lean out at WOT. (haven't ruled out mechanical fuel pump though)

Just thought Id run the specs past you guys and see if there's anything that might raise a red flag


CAR - weight is 2850lbs, 4 speed manual and 3.9:1 read ends with 24.5” tyres.
ENGINE - HOLDEN 308ci (3.062” stroke) 4.030" BORE
Forged flat tops 10:1 comp
1.94/1.60 ported heads
Dual plane manifold (Edelbrock performer)
Crowed 236/246 112 solid camshaft (0.520"/0.530")
1.65 roller rockers
Timing 18-36

Rebuilt carb new bushings in throttle shafts, cliff parts throughout.

QJET 7045281 DATE 0165 side entry fuel inlet (3/8" fuel line)
FLOAT 1/4"
N/S 0.135"
JET 77
RODS 44B (WERE 50B)
SECONDARY RODS AX
HANGER F
Idle tubes 0.035" (were 0.029")
DCR 0.0575 (were 0.040)
UPPER IDLE AIR BLEED 0.070"
LOWER IDLE AIR BLEED 0.061"
UPPER MAIN AIR BLEEDS 0.120"/0.120"
IDLE BYPASS 0.109"
IDLE MIXTURE HOLES 0.089"
SECONDARY EMULSION TUBES LOWER RESTRICTOR HOLE 0.026"
BIG FEED TUBES NEXT TO THOSE 0.077"
SECONDARY WELL RESTRICTOR 0.038"
AIR FLAP DISTANCE 1.429" (?)

[Mikecaterina]

ACCEL. PUMP DISCHARGE NOZZLES 0.022"

[Cliff Ruggles]

Do you have control of the idle A/F with the idle mixture screws?

Really "stinky" exhaust can be lean and that condition usually stinks worse than if it were too rich.

What RPM is the idle speed set to? 

You should be able to turn in the mixture screws and slow the idle down, then back them up to smooth it out some.

Also, what is the vacuum reading at idle speed?

[Mikecaterina]

Idle is smooth 700-750rpm

I have full control of idle mixture screws, can stall engine seating screws.

I will take for a good drive this weekend and get a vacuum ready once hot.

[Mikecaterina]

12” hg@ 750rpm
That’s idle speed screw backed right out

[77cruiser]

Is the idle mixture set to highest idle RPM/vac?

[Mikecaterina]

Yes, idle mixtures set to highest reading/smoothest idle then adjusted lean (clockwise) 1/4 turn just as vacuum signal wants to start moving lower

[Cliff Ruggles]

If you can acheive smooth idle then turn the mixture screws in and slow the engine you are able to lean it out so it's not stinking because it's too rich.  When I set the idle mixture screws I'll turn each one in until I just hear the engine start to slow down then back them up about 1/4  turn or so till it smooths out.  Or basically the best idle quality at the leanest settings.  Turning them in from that point to lean it up will stink worse than having a little more fuel to it.

You may find that the overlap from that much camshaft on a small CID engine is most of the problem.  No mention of how much timing you have at idle but it's also a player in idle quality and stinky exhaust.....

[Mikecaterina]

Hi Cliff, 18 deg @ idle

Went for another drive can see light puff of black smoke at tail pipe when idling. Not bad but noticeable to me.
Yes camshaft is probably a tad too big and not enough compression I think may be a problem.

If I cover carb with hand at idle, engine will pretty much stall, if I pull vac line off idle spikes up around 1000rpm

Same as if I do a tip in test at 2000rpm, covering drops rpm dramatically and pulling vac hose increases rpm.

Had another good look at nozzles whilst running, looked dry. After I shut down nozzles look wet but nothing on blades is this normal?

Thanks