6bbl guys...

[dstryr]

It appears by the plugs and wideband I'm still off on the jetting so to keep from taking the carbs apart any more times than I have to I wanted to ask if I'm heading in the right direction.

505", 10.2:1,  ported Source heads flowing ~ 285cfm intake, 1.5:1 roller rockers

XS290S cam:
Intake Duration at 050 inch Lift: 252
Exhaust Duration at 050 inch Lift: 260
Duration at 050 inch Lift: 252 int./260 exh.
Advertised Intake Duration: 290
Advertised Exhaust Duration: 298
Advertised Duration: 290 int./298 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.540 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.558 in.
Valve Lift with Factory Rocker Arm Ratio: 0.540 int./0.558 exh.
Lobe Separation (degrees): 110



Here are my notes from May 31:

Idle 875 rpm                   13.0 a/f
cruise, approx 3200rpm    11.2
WOT                             12.5

Jetting L/R
Front          83/83
Ctr             64/64
Rear           83/83



I think I want to be somewhere around these numbers:


Idle               14-15:1
Cruise            14-15:1
moderate load 13-14:1
WOT             Low 12-Low13:1

Cruise is way rich so I'm thinking drop 2 jets sizes in the center and to stay in the 12.5 range at WOT add one jet size to the outboards.  After my last tear down I finally got the outboard idle screws loose and can adjust them, and all 6 idle screws do affect the idle characteristics.

Make sense?

Thanks!

[firefighter3931]

I think you're on the right track Frank   

Mine is at :

14 idle
13.5 cruise
12.8-13 WOT

Plugs stay clean and it idles nice at 1100 rpm 

Less jet on the center carb and a bit more on the outboards will get r done 


Ron

[ottawamerc]

Hey great post please keep us updated, I have  similar results with my 6Pak setup too and I'm interested in your next numbers (saves me from tearing my carbs apart over and over )

Scott

[dstryr]

Okay, went to 63's in the center and 84s out and the plugs are white.  The wideband is telling me 14:1 at idle, 12.2 at cruise and 13ish under moderate load and WOT, and I'm getting some misfiring at lower, 3000 or so, RPMs when I drop the hammer.  Lean miss?  

And, plugs are white so now thinking the wideband isn't dead on but at least the plugs are no longer black.

I recommend using the 1/32" paper gaskets under the carbs.  The 1/16" composites often allow the base to twist and bind the throttle shafts.  I haven't found the paper gaskets on-line so next round will buy some felpro or similar paper to cut my own.  

[Troy]

This will be helpful. I have a wideband (not hooked up yet) and my car has been running like garbage. Rich all the time it seems. I also have those special screws/driver to adjust the idle without pulling the carbs.

Troy

[dstryr]

Too lean?

[firefighter3931]

Jetting doesn't look too bad based on the porcelin and bottom threads on the plug. 

The heat range is definately off.....you need a colder plug. I would go one heat range colder.



Ron