I'm new. Please give me a break. I have an 86 IROC with 305 TPI.

What is invovles in putting a 350 under the original tpi?

 

well if you want to do it right

-requird stuff-

350 block
22+ pound injectors (accel/holleys are nice)
new prom

-optional stuff-

52mm throttle body
new runners
ported base
ported plenum
headers
high flow cat

or a :hail: superram would really wakeup a built 350 and still have a chance at passing emissions.

 

Welcome aboard.

Break granted.

1) Buy a 350.
2) Remove the 305.
3) Put the stuff from the 305 that the 350 doesn't have (if the 350 is '85-earlier, you'll need a 153-tooth flexplate for a two-piece rear main seal crank. If the 350 is '87-later, you'll need to elongate the center two intake base mount bolts on each side to match the bolt angle in the heads).
4) Install the 350.

While you're at it, an adjustable fuel pressure regulator will help you tune the system (same true if you keep the 305). 350 TPI's used 22 lb injectors from the factory vs. 19 lb for 305. With the AFPR, you can get by with the 19's on the 350. But, if you need to raise pressure too high (above 48 or so), consider 22 lb'rs.

 

come to think of it. i'm just about done putting a 383/superram combo in mine if I were to do it again. I would have gone with a 400 bigger is better right? how much hp are you shooting for?

 

250-300? Is that doable? I would love to do more but am trying to keep in mind that my 16 year old son will be driving it for a couple of years until the old man reclaims it!

 

300? don't you want your sun to be known as hell on wheels? kidding

300 can be done with the listed mods below and of course a nice 350 buttom end to go with it.

you need to get new larger runners and get the plenum and base plate portmatched with a 52mm throttlebody. and of course you need a buttom end to support it..
larger injectors to 22 pound is good for 300hp.

 

52mm tb....
19# injectors..


You dont need a 52mm tb.. its not gunna gain you anything but debt. Use the money and get a high flow base for the tpi system if you plan on keeping the tpi. Your gunna need a new knock sensor for 350's. Gunna need 22# injectors, cause even at 50psi, the 19# will run about 21.2 which is not enuff for the 350. Also a 350 prom, but if you want to max the power, get a custom prom burned.. NOT hypercrap or jet or anything like that... thoes suck and for the price you can make your own. headers and exhaust are a must. 300hp is easy with a 350. Head work, cam, free flowing intake, and your at 300+ with ease... just make sure the engine is in good tune and everything checks out. Also for some cheap HP you can find a set of Corvette alumin heads off there L98 block and have them ported, valve job, and spring seat enlarged for larger springs for the cam... You will raise the compression a great deal and also increase your power out put. A good bottom end, good heads, cam and intake with free flowing exhaust will get you 300hp. Dont forget about traction and drive line stuff too. good luck.