73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: chanslk on May 25, 2014, 10:07:38 pm
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I just got this 84 Chevy this weekend and I think it has a 305 engine in it. I was wondering if I changed the engine to a 350 would I have to change the transmission also. And it also has a carb and I would like to change that to andwas wondering how much trouble would that be. Like does that mean making the truck computerize and needing a electronic fuel pump.
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Welcome the site. Changing from a 305 t a 350 should not be a big deal regardless what transmission you have.
As far as taking off the carb., are you talking about going to TBI, EFI or what ? TBI is easier, EFI would be harder, and yes you would need the ECS and wiring.
You need to make some decisions and let us know so we can further help you.
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Also if you change to a 350 and the dipstick is on the drivers side your exhaust manifolds will not work your transmission will work all mounts and accessories will also work
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Thanks for the welcome and information. The oil dip stick is on the passenger side and if I did change it to a tbi intake does that mean I would have to change the fuel pump that comes on the block and gas tank on truck to a gas tank with eleictronic fuel injection?
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Thanks for the welcome and information. The oil dip stick is on the passenger side and if I did change it to a tbi intake does that mean I would have to change the fuel pump that comes on the block and gas tank on truck to a gas tank with eleictronic fuel injection?
Yup. You need the electric fuel pump and the internally baffled gas tank.
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So it would be better to just leave the carb on and no changing the intake or gas tank.
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You pays your money and you takes your choice. I like the carb on mine, because I can tinker with it and it doesn't have a computer. I do the computer thing for work, have for decades, and I'd just as soon not. Adjusting things with a screwdriver and a needle change is a change of pace for me.
Fuel injection is much more expensive to set up, but gets you the best performance and gas mileage, as long as that is how the computer is set up. Having a computer you can adjust with software on a laptop and a USB port is good so you can adjust it, because canned factory settings may or may not be best.
A carb is cheaper, but will never be as accurate a mixture as a closed-loop system like fuel injection. You still have to tune it, but you can do that with an A/FR meter and some needles and jets and a screwdriver. You won't get as good mileage from a carb, ever, but you don't need electric fuel pump and baffled tank.
Depending on the 350 setup, I have the correct settings for the Edelbrock 1406. Also, the Qjet on your 305 will be very close as is.
So whatcha gonna do for a 350? How much do you want to spend? New or used?
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Rich, why an internally baffled fuel tank? I have the comp, harness and 350 tbi as I am planning this switch on my 86.
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Gusgusa1, I know you asked Rich, but here is my understanding of why you need a baffled fuel tank.
Fuel injection needs a "well" in the fuel tank to keep the pump submerged at all times as the fuel injection needs constant fuel supply to keep the pressure constant to the injectors. Crabs have a fuel bowl to compensate for minor variances in fuel supply so if there is an instantaneous lack of fuel at the tank pick-up, say like at a sudden stop when the fuel sloshes around, the crab sees an uninterrupted supply of fuel. Fuel injection does not have the internal fuel buffer in the fuel rail/supply line. If the pick-runs dry even for a instant, the engine could miss fire or stall.
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Gusgusa1, I know you asked Rich, but here is my understanding of why you need a baffled fuel tank.
Fuel injection needs a "well" in the fuel tank to keep the pump submerged at all times as the fuel injection needs constant fuel supply to keep the pressure constant to the injectors. Crabs have a fuel bowl to compensate for minor variances in fuel supply so if there is an instantaneous lack of fuel at the tank pick-up, say like at a sudden stop when the fuel sloshes around, the crab sees an uninterrupted supply of fuel. Fuel injection does not have the internal fuel buffer in the fuel rail/supply line. If the pick-runs dry even for a instant, the engine could miss fire or stall.
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Like he said. Perfect explanation. One added detail: if the fuel pump on a carbed engine sucks air, that air will vent through the carb's float bowl vents, and the float bowl valve will stay open until the fuel level rises to the set level. This is only an issue when the tank is low, to the point that when you go up or down a hill the pickup on the bottom of the sender is uncovered. If you never go under, say, 1/4 tank, you won't have any problem with an unbaffled tank.
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As long as you don't run it completely empty and drive erratically you will be fine without the baffles in the tank...
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Perfect thanks guys