Is it worth modding a 305 TBI?

or would it be better to get a 350 and bore it out = 383?

If I do mod the 305 could it be fast?? and would the driver notice the difference??

Im thinking of getting a 350 and have it bored out to the max.

From everything Iv'e read and seen here you guys make the LO3 sound like a worthless piece of junk... but I was wondering if I would make my 305 TBI and convert it into a (TPI). Would I notice the difference and would it be much much faster?

 

The 305 can be fast. IMO there's nothing wrong with modding one, as long as one can avoid 305-specific parts (heads come to mind).

External bolt-ons such as intakes, cams, exhaust, etc., will all pay off in power gains.

Where you get to the point of diminishing returns however, is when you touch the short block. 350 cores are SO CHEAP, and SO PLENTIFUL, and make SO MUCH DIFFERENCE, that it's senseless to spend a dime on a 305 one. Those other 45 inches are the cheapest HP that money can buy; by a factor of about 5 to 1. i.e., it will cost you 5 times as much to get those HP any other way, besides the bore upgrade. About the stupidest thing of all, is those 334 stroker kits.

You don't turn a 350 into a 383 by boring it out. You do that by putting a different crank in it; with the stroke of a 400.

The L03 is truly a pitiful motor. Not only because it's a 305; but mostly because SO MUCH has to be replaced, in order to overcome all of its limitations. Just slapping a TPI on top of one won't do much good. You'd need to replace the exhaust, EVERY SINGLE PIECE, from the heads to the street, with something that doesn't preserve the L03 bottleneck; the cam; and above all, get rid of the swirl-port heads. Plus, the car is crippled, with grocery-cart gears, and no posi. A TPI 305 is faster than a L03 for a whole lot of reasons beides just the intake manifold. People always want to un-bolt and re-bolt the big shiny obvious part you see when you open the hood, which isn't where the L03's problems really are; as usual, the parts you don't see, are what makes the most difference. Basically, it's an entire package.

 

I agree. L03s SUCK! I had one until a year ago when I finally swapped it out with a 350.

When I had it though it was a good engine to learn on. I did headers, intake, gears, posi, exhaust, roller rockers (useless btw), a 350 truck cam, and, the thing that made the biggest difference, ported my heads. I bought some used 305 heads on ebay and ported them myself, and then swapped them with the existing heads. It worked good because I could still drive the car around while porting my heads.

There is quite a bit you can do to improve your L03 engine. Just dont expect to be running 13s.

 

Yeah.. I'll just get a 350 block and go from there.

 

Everything RB83L69 said about the L03 is true. It real problem is not the 305 ci's but everything on top of the block.

I moded my L03 for three reasons. First I had never worked on an engine before this and I need the experience. Second, I didn't want to pull the engine (didn't have the tools or the space to do it). Thirdly, If I was going to build an engine I was going to do it right and build a monster, I didn't have the money, the will or the knowledge to do that then.

I installed Torquer 305 heads, a LT1 cam, a carb intake and learned to program the computer and I'm getting ~265 hp at the crank. I could have more if the stock TBI flowed more air and fuel. I'm next going to install a TPI intake and then a bigger cam and I'll teach myself to program the TPIs computer. Once that is done I'll finally start building the 350 that I really want.

Good luck with the 305.

 

Get an exhaust FIRST. The exhaust that's on there is choking the L03. It will choke a 350 even worse.

If the motor you have is in good shape, then instead of yanking it and swapping it, spend your money and resources on stuff that will also cripple anything else you put into the car. Exhaust, gears, torque converter, stuff like that. Leave the motor alone if it's not broke, and just use it.

 

Should I remove the catalytic converter? or gut it out? or get a edelbrock one? I hear that this robs alot of HP as well...

 

A properly chosen cat "robs" very little HP.

Get yourself a set of chassis-specific headers for one of these cars, BUT NOT FOR L03; get them for something like a 89 350 TPI without G92. I'd suggest SLP, or maybe Edelbrock. Get them ceramic coated if you can AT ALL afford it, it makes a HUGE difference in the longevity of everything rubber or plastic under the hood (wiring, hoses, sensors, relays, etc.). Then get a Catco or CarSound direct-fit cat for the same application, and a cat-back exhaust such as from Hooker, Dynomax, Slowmaster, Edelbrock, etc. etc. etc. for the same application. You'll have to do THE WHOLE thing, all at once, because none of it will fit with the L03 stuff. The goal is to get all the L03 parts off, EVERY SINGLE PIECE.