340 power problems in a truck

ddale · 01-25-2007, 08:10 PM

I recently rebuilt a 340 it lacks power and gets poor fuel milage. I put the engine in a 77 dodge D100 stepside, 727 trans and shift kit, 3.55 posi. I get 10 miles to the gallon pulling a load or running empty. The engine is bored 30 over with 9.3:1 pistons, a towing cam, edelbroch dual plane, holley 600 single pumper carberator. I have tried 2 barrels and 3 different 4 barrels, all the same result. I've had the heads reworked for unleaded gas, changed out springs and valves. The truck has a stock electronic ignition. I was wondering if recurving the distributor would help. I don't know if the distributor in it is from a 318, 360, or the 340. My goal is more centered on low end torque than on strait horsepower, any help out there would help. there is not much help out there for dodge truck owners, at least not for trucks under $30,000 or more than 10 years old.

joedirt77 · 01-31-2007, 07:41 PM

you didn't say what cam you have (specs), or what heads (valves) you have. what are you running for exhaust? without more details, i'd suggest check your basic tune-up. i think you are right about your mileage, it should be higher.

1 Bad Mirada · 02-01-2007, 05:46 PM

have you done a plug check? does it look too lean? rich?

01-25-2007, 08:10 PM	#1 (permalink)
ddale Junior Member Join Date: Jan 2007 Posts: 1	340 power problems in a truck I recently rebuilt a 340 it lacks power and gets poor fuel milage. I put the engine in a 77 dodge D100 stepside, 727 trans and shift kit, 3.55 posi. I get 10 miles to the gallon pulling a load or running empty. The engine is bored 30 over with 9.3:1 pistons, a towing cam, edelbroch dual plane, holley 600 single pumper carberator. I have tried 2 barrels and 3 different 4 barrels, all the same result. I've had the heads reworked for unleaded gas, changed out springs and valves. The truck has a stock electronic ignition. I was wondering if recurving the distributor would help. I don't know if the distributor in it is from a 318, 360, or the 340. My goal is more centered on low end torque than on strait horsepower, any help out there would help. there is not much help out there for dodge truck owners, at least not for trucks under $30,000 or more than 10 years old.

01-31-2007, 07:41 PM	#2 (permalink)
joedirt77 Member Join Date: Oct 2006 Posts: 63	mileage you didn't say what cam you have (specs), or what heads (valves) you have. what are you running for exhaust? without more details, i'd suggest check your basic tune-up. i think you are right about your mileage, it should be higher.

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02-01-2007, 05:46 PM	#3 (permalink)
1 Bad Mirada Administrator Join Date: May 2006 Posts: 100	have you done a plug check? does it look too lean? rich?