I'm getting ready to start my 406 speed density set up and need some advice on my initial chip burn. Most posts advise that retrofits of SD to older engines require a fuel reduction across the board due to a larger duration cam (and poor VE) indicating to the ECM that the engine is already under load.
About how much fuel needs to be reduced for my initial startup - 5, 10, 15%?

406ci
Edelbrock Aluminum RPM heads with 70cc chambers
Crane 214/224 112 degree cam
Lingenfelter intake manifold and SLP runners with stock plenum
52mm BBK throttlebody

Thanks for any input.

 

Little bitty cam and a lot of motor.

My guess if it were mine would be to trim it back about 10% on the below 2krpm areas and see what happens.

I tend to err being a little lean(emphasis little bit, not no rev backfiring out the intake lean) on first start up vs. wash the rings down rich.

Always double check everything before firing and get the distrib set as close to 6deg as possible before firing.

Start with dataloggers on obvioulsy as well.

Shouldnt be too bad with that cam in a 406.

Did you match every else in the chip as well? IC, engine size, etc?

later
Jeremy

 

Jeremy,
Thanks for the advice. That's just what I'm looking for.
I'll double check the rest of the specs in the bin specific for a 406ci and manual transmission.

VR,
Alan

 

Bigger injectors will mess with the startup fuel by adding more fuel also.
Some say to lower the crank fuel scalar by the same amount as the injectors are increased in size.
I'd guess that a 406 with that cam will be very close to stock for start up fuel requirements.
Also, with the bigger motor, if the batt,starter, cables aren't adequate, you'll drop the system voltage during crank a little more than stock. Which will remove fuel.
Lot's of variables to consider.

 

Z69,
Thanks for mentioning that aspect of the fuel injectors and the electrical system.

I'm using 30# ford injectors, so I'll have to take that into consideration (and the fact that they are rated at a different pressure than GM injectors too).

I didn't think about the electrical power requirements affecting the computer, but did upgrade a few things since everything else is "new". I've installed a 1990 serpentine system with rebuilt 110 amp alternator but deleted the smog and A/C. I modified the wiring to remove the old regulator and upgraded the alternator wiring to 6 gauge. I'll make sure to charge that battery up since it's been sitting for a few months

I have not burned the new chip yet, but I did install the computer and turn the ignition key for a "smoke" test. I could hear the fuel pump come on for a couple of seconds and then go off, so it seems the computer is checking the oil pressure sensor and cutting the fuel pump power like it should. None of the harness wires started smoking so I took that as a good sign so far.

VR,
DZcode