Thread: 305 to 350 swap

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i was looking at some of these threads and it seems like alot of you know what your talking about. i know most of you guys are hot rodders but i got a 95 chevy k 1500 i have just put a 6 inch lift with 35 inch tires on it. and that 305 is gutless with them on there. but i looking for some help how to mildly build a 350. i got the motor torn down and everything looks good. im on a 2,000 dollar budget. what are some cheap easy mods i can do? im looking for about 360 to 380 horses. with lots of low end torque when mudding.
thanks for any opinions.......... kyle

chances are, you won't achive that using your factory TBI, you need a 350 TBI manifold. get vortech heads, change computer w/ 1 from a '96 up Vortech 350. computer friendly cam ect... it'll work ok

I've built a few TBI engines and the major restriction is cam duration. Anything more than 212 degrees causes problems with the stock computer. I've used this cam in two different engines using the stock computer and had great results.
Chevy Ram Jet, 196/206 Duration @ 0.050, Hydraulic Roller Camshaft


CAMSHAFT
Part #14097395Retail Price: $154.95


Quantity:



This GM Performance Parts Hydraulic Camshaft is for a 350 Ram Jet and the 383 truck engine with 1.5 rockers. Makes great torque for daily driven vehicles and tow trucks. Can be used in 1986-99 305-350 Chevrolet engines. The step nose design is for cars and trucks originally equipped with a hydraulic roller camshaft. Can easily replace a hydraulic camshaft in 1986-99 blocks with lifter kit 12371042. Contains the fuel pump eccentric for use with mechanical fuel pumps

What size tires were on it before? If it was a big jump in size a rear end gear change might be in order....

Originally Posted by ceh383

What size tires were on it before? If it was a big jump in size a rear end gear change might be in order....

i was thinking the same thing.... the larger the tires the shorter the gear, unless you're just trying to build a ton of horsepower and waste a lot of gas

if my memory still serves me correctly, the flexplate from a 305 will not work on a 350. a little research on this might save you some time before you swap out the motors.

A computer from a 96 up truck will NOT work with a TBI, the injection control AND the engine sensors are completely different. If you desire to keep the TBI, there are improvements such as an Edelbrock manifold that will work. The TBI computer will need to be changed to meet the larger engine's fuel demand..a 95 350 computer is the simple way or perhaps you can find someone who hacks TBI computers. Figure that your effective gearing was reduced by the ratio of the tire diameters...if the previous tire was 28" dia and you changed to 35" dia, you effectively changed your 3.55 rear gears to a 2.84 gear!
If you had 3.73 rear gears, you effectively changed them to a 2.98....no wonder you dont have any beans.

Like most folks say, the larger increase in tire diameter plus the tire's rotational inertia increase will make your truck a slug, especially if it is an automatic. A steeper set of gears (front and rear if it is a 4wd) will help.

mike in tucson

ok thank you for all the help. ill have to look into everything. thanks again for everything

Originally Posted by robot

A computer from a 96 up truck will NOT work with a TBI, the injection control AND the engine sensors are completely different. If you desire to keep the TBI, there are improvements such as an Edelbrock manifold that will work. The TBI computer will need to be changed to meet the larger engine's fuel demand..a 95 350 computer is the simple way or perhaps you can find someone who hacks TBI computers. Figure that your effective gearing was reduced by the ratio of the tire diameters...if the previous tire was 28" dia and you changed to 35" dia, you effectively changed your 3.55 rear gears to a 2.84 gear!
If you had 3.73 rear gears, you effectively changed them to a 2.98....no wonder you dont have any beans.

Like most folks say, the larger increase in tire diameter plus the tire's rotational inertia increase will make your truck a slug, especially if it is an automatic. A steeper set of gears (front and rear if it is a 4wd) will help.

mike in tucson

Guess I wrote that wrong. I was suggesting changing the computer and all wiring along w/ the Factory Vortech MPFI intake.

good rule of thumb: always get the flywheel when you scavenge an engine.