rebuilt carb recipe

[scooter]

Cliff
I spoke with you on the phone a few weeks ago when I ordered the rebuild kit. I have been studying your book and am trying to get my ducks in a row and could use some help as I finish up my carb rebuild. This is an off road only vehicle and I am looking for some help with a recipe and any other advice you can provide. I have listed the specs of my engine and carburetor (17080213) in its current state. If some of the numbers don’t look right to you I may be measuring in the wrong locations, sorry still trying to learn.

My engine: Small block Chevy 400 stock bottom end with vortec heads, dual plane aluminum intake and approximately 9.5 compression.
Cam specs are: Duration @.05 intake .218 exhaust .226 Lobe separation 111 and lift intake .462 exhaust .480.

Idle tube:                                                      .036
Idle down channel:                                         .055
Low idle air bleed:                                          .063
Upper idle air bleed:                                       .073
Accelerator pump discharge holes:                   I am not sure exactly where these are   
Main air bleed (main body):         
Main air bleed (air horn):                     .048
Main Jet:                                                         73
Primary metering rods:                                    49M
Fuel inlet:                                                      .135
Secondary POE well restriction:                       .040
Secondary POE restriction:                              not sure where these are
Secondary tube restriction:                             .036
Secondary hanger:                                    The only marking on it was 33797
Secondary metering rods:                               DA
Air flap open distance:                     1.375
Secondary flap spring:               Not sure how to tell
Choke pull-off release time :   Front: 3-1/2 seconds
                            Rear: 1-1/2 seconds
DCR:                                     .055      
Idle by pass air:                                            .111
Idle mixture screw hole size                           .090
Thanks for any and all help you can provide!

[Cliff Ruggles]

Those specs look fine for what you are doing.  That particular carburetor has generous idle and off idle fuel delivery, so should be very close for your engine set-up.

Don't worry about the accl pump discharge holes, they are deep in the airhorn and difficult to measure, and already big enough for what you are doing......Cliff

[scooter]

Cliff, thanks for your help so far. I am getting really close to having this baby dialed in and cant wait to run it Through its paces.
I finally got the carb together and on the truck. Its not street legal so the only testing i have been able to do is in a parking lot. It seems to start,idle and run good. The problem i am having is after a holeshot (when its in gear and i accelerate hard (WOT) it runs great until i let off the throttle). When i go from WOT and let off the throttle it stalls. It seems to start right back up after this. I have done the tip in procedure. the idle mixture screws seem to be set pretty close. The timing specs are set at: Initial 12, Mechanical 22, and Vacuum 10 for a total of 44. Vacuum is around 16 at idle (700 RPM).  Mechanical timing starts about 1000RPM and is all in at 2700RPM. I am not sure where my problem is. I am running a stock fuel pump but i do not think i am running out of fuel because it runs strong until i let off the gas and that is when it dies. Is my timing off? or maybe my idle set to low? I have done a lot of searching on the net with no results so i am back here asking the Master!

Thank you

[Cliff Ruggles]

If it runs great at WOT then it can't be off much.  The intake will have a lot of fuel in the runners (wet flow system) if you quickly close the throttle during a WOT run, so it may take a second or two to clean out, but it shouldn't stall.

The only time this usually happens is when the vehicle isn't moving and you hit it really hard, then there is no coasting time or really any time to clear the fuel from the intake with the throttle plates closed and engine idling.....Cliff