305 to 350 in 88 IROC

is there anything that needs to be changed in the car to swap to a 350 motor? Will the 305 TPI and intake work and the computer? Any help will be appreciated

You can swap everything over, assuming your donor 350 is a roller cam, one piece real-main seal engine like your original 305. Otherwise, you need to pay attention to the middle bolt holes of the intake manifold: There was a change in the angle of these bolts during the 1987 model year. If you have early model heads, you will need to oblong the holes in the intake, or find a 1985-1986 intake manifold. (I happen to have one in my pile of junk, BTW) If you want it to run like a stock 1988 350, you need to get the proper cam, or something computer-friendly anyway. You also need to change from 19 pound to 22 pound fuel injectors, and change the PROM in the ECM.

Thanks for the info! Its great to know that there are places like this to go for questions.

If the engine is a pre 1987 350 you might just want to get a intake and carb for the 350. All you will have to do is get a return style inline fuel pressure regulator and regulate the fuel pressure down to around +/- 7 psi. Good luck with the swap.


- Charlie

if you went to a stock 350 with a carb might as well keep the 305 TPI,

you need 350 injectors, Knock sensor, the modual that controls the knock sensor and a 350 chip,

you cna go after market and buy a custom 350 ship, better off, you get a little more power that way,

MAF is fairly can friendly, you can get away with a fairly aggresive FI cam with out computer mods

if you went to a stock 350 with a carb might as well keep the 305 TPI,

you need 350 injectors, Knock sensor, the modual that controls the knock sensor and a 350 chip,

you cna go after market and buy a custom 350 ship, better off, you get a little more power that way,

MAF is fairly can friendly, you can get away with a fairly aggresive FI cam with out computer mods

There is alot more room to grow with a carb'd 350 and tuning it will be alot easier than learning to burn proms. A "custom" chip as in hypertech, jet etc etc. will not give you more power and in some cases it can make the engine have less power. If you do decide to keep the tpi buy prom burning equipment, its pretty cheap and you can upgrade proms as you add modifications. Not trying to talk **** just throwing out some facts.

- Charlie

I burn custom proms, its just as easy as tuning a carbed 350 when you get right down to basics, both take undeerstanding fuel and timing,

only with TPI its far more versitial,
some people say hp is limited in MAF, but I'm currently working on a car that pulled 400rwhp and I've only just started tuning

I never siad jet or hypertech,
you can easily copy what a hypertech or jetchip does by bumping your timing a couple degrees and running a manual fan switch with a lower temp T-stat,

a buddy of mine was running a consistant 89mph in the 1/4 and 70mph in the 1/8,
he had his timing bumped and full time fans with a low T-stat,
we put a hypertech chip in his car, made absolutly no difference at all,
my basic starter chip, gave him 92mph in the 1/4 and 74mph in the 1/8
without any custom tuning, could get it faster with some time into the chip and my wide band O2 on it

his time wasn't any faster but his 60' times went in the crapper cause he couldn't hook with the torque my chip gave him, needs some more practice

hypertech is not a "custom" chip..........

I have a 1989 Iroc 5.7, It starts fine when it is cold. Once you run it a while, and turn it off, It will only start by holding the accelerator to the floor. It then runs rough and soot come out the tail pipes. It has some hesitation hot or cold. I have change the fuel filter and checked the converter and neither helped. What is my problem??? Thanks

I have a 1989 Iroc 5.7, It starts fine when it is cold. Once you run it a while, and turn it off, It will only start by holding the accelerator to the floor. It then runs rough and soot come out the tail pipes. It has some hesitation hot or cold. I have change the fuel filter and checked the converter and neither helped. What is my problem??? Thanks
start a new thread, I'll answer there