[roboroofer]

I have a ck 3500 with a 5.7 litre engine running on a 300a propane system. I have recently failed 4 etests. I've changed the plugs to Bosch Platinum 2, new cap, rotor, plug wires, egr valve and solenoid, map sensor, tps, iac, catalytic, air filter. The engine is still putting out high hydrocarbons when drive at an idle. It seems to have a misfire that I beleive is causing the hydrocarbons. Any idea what it could be?

 

[RDDC]

I just talked to a guy about the Impco 300A set up - I believe that is a dual fuel propane carb and actually puts out more cfm than a normal 225 or 425. The guy told me to go with an Impco 425 on a SBC. I hope this helps in some way, but I am sure this carbs were used in the dual fuel set up.