4.3 to 305/350 question

[bedo`]

I've got a 4.3 in my monte now and think its about time to swap it out

I was thinking of grabbing a local 305/350 (which ever is cheaper) and slapping a FI system on it since I already got the FI tank and lines..the computer and everything comes with the holley stealth ram kit. The reason I'm wanting to go for FI is because I don't have any clue on how to mess with carbs and need something reliable for winter time (heard carbs can be a b*tch in winter)

or should I snoop around for a newer LS based 5.3 truck engine? I know there will be hood clearance issues with the intake. But that is all I know about them.

Overall power would be nice but I'm really looking into reliability and MPG mostly..I would like to keep A/C and all my accessories and run my original transmission if I can.

the cheapest route is always the best too 😀


or I was just looking too..could I get a complete TPI system from a camaro with the computer and it should work fine right? they look cheaper then the holley
or any other suggestions?

 

[dogsht]

Get a carberated 350. Use an electric choke Q-jet. Best bang for the buck least amount of problems. Use a return style fuel pressure regulator such as the Mallory 4309 from Jegs etc. It comes with a little allen wrench to set fuel pressure. Get a cheap fuel pressure gauge to set the fuel pressure at about 5 psi. Your done. OK if your carb linkage doesn't match up you may have to salvage yard or auto part store source some linkage.

The LS conversion is not cheap or easy. If you need or want to replace the fuel pump since its old and while you are in there check out www.racetronix.com click Buick GN pump. Its drop in & has info as to how to get better voltage to your pump for better service.

 

[bedo`]

so what if the engine doesn't come with an electric choke wheres a good place to get one? I see JEGS offers re manufactured q-jet electric choke..would those work fine? and I wouldn't need a computer for it to work would I?

thanks

 

[dogsht]

Yea Jegs would work fine although I would be more inclined to get one from a smaller outfit like Sparky's carbs or many others on the internet that specialize in carbs and do their own. Jegs etc buys them bulk and resells them. Consistent quality is better and they will more likely per your request set the metering rods & jets up for your engine/car. So it should be closer to spot on rather than generic if you will. No computer.

 

[bedo`]

do you know what kind of MPG I could be getting? what about a 500cfm one?

 

[dogsht]

There is not much difference in fuel mileage from a well set up vacuum advance spreadbore such as the Q-jet and fuel injection. Things like rear gears, overdrive transmissions, lock up converters, even low tires, often make as much of a difference. A square bore mechanical double pumper carberator on the other hand is going to slobber fuel.

Fuel mileage depends on a combination of many things and how well the whole package from fuel in to tire diameter and everything in between. Even speed weight road surface displacement octane compression and aerodynamics figure into efficiency. You can see in my signature I managed to get 17.0 mpg hwy with a Q-jet carbed 509ci in my Cutlass and 22.0 hwy with my 231ci fuel injected GN. 15 to 17 hwy would probably be most common with a carberated 350. Naturally in town or a mix will get less mpg. Oh yea carb cfm rateing does not matter in the mileage of a Q-jet as the tripple venturi system only allows in the amount of air and fuel that the engine vacuum pulls in. CFM rateing does seem to make some difference in the more crude system of a square bore such as a Holley. This is in part why a squarebore design makes for a better race carb but not as good of a street carb.