So what are the pros and cons. In your opinion whats better and why. Gas mileage,performance,quality...the whole package. Im thinking 350 would be better.

 

305=Slightly better on gas
350= Better for everything else

 

woah... who would ask this?

 

Not everyone prefers a 350 if thats what your getting at.

 

305's are great if you want to build a mild street car but if you're trying to go fast you'll want a 350.

 

It would depend upon the end use. A decent running used 305 can be picked up for a song, and may be all that is required for that daily driver. If you want a performance vehicle where get-up-an-go is paramount, then a 383 or 406 would be better.

In the middle is the 350. Cost more then a used running 305, but cheaper then a used running 383/406.

RBob.

 

I never understood this question. If the concern for the build is gas milage, pick the right cam for the 350. Similar gas milage, better performance. I don't see any lure for a 305 other than for a lawn decoration or a submerged mooring.

 

The 305 vs. 350 discussion goes on ad nauseum. Those without a firm grasp on basic physics will try to tell you a 305 can be built to be just as fast as a 350. The two problems with that are: 1) power is produced by efficently pumping air & fuel in & out of the engine; and 2) the small bore of the 305 shrouds SBC head valves so that process will never be as efficient as it is with a 350's 4" bore.

Personally, my 'roided 305 was no better on economy than my 350 is now, with similar equipment, and the 350 is a second & a quarter quicker in the 1/4 than the 305 was.

(Since the search function is down, I'll let this thread stay open as long as it doesn't turn into a food fight.)

 

if the 305 was as bad as every1 sayz, y would GM have put it in so many of their thirdgen models?

 

They didn't just use it in thirdgen models. The 305 served its purpose well. It ran marginally cleaner, got better fuel mileage in CAFE testing, had the low-mid range torque to pull a high numerical axle gear and OD, had some HP to it, and was based off the existing 350 to keep things cheap.

That being said, the 305 can be a decent street engine. You can make a 305 go pretty damn fast, but a similarly moded 350 will walk away from you every time.

 

Back when I was in high school we had a saying. "The 305 is like Disco, it
s u c k s."

Back then we would not have even dreamed of building up a 305. However, the 305 has come a long way since then, and I will give credit to GM for extracting the power from the shrouded valve mill that they did. It was a good motor in my opinion for a grocery getter and it served the F-Body alright, but not much more than that. In today's world the 305 is not as bad of a choice as was back then. There are now performance pistons available (there were none affordable back then), and we have Vortec heads etc now that can greatly improve the performance of the 305 along with other mods available such as fuel injection.

If I had not had my garage, I would not have considered pulling the 305 from my Firebird, and that would have been the only reason for me to retain the 305. I would have done bolt-ones only, and once I had an opportunity, a 350 would have been dropped in.

I still have a problem getting the old way of thinking about the 305 out of my head... and I always did hate Disco.

 

The easy answer you can always tell people: If you already have a healthy 305 bottom end, and just want something to have fun with, go ahead and mod it. If you realy want to RACE, then go bigger.

Theres nothing wrong with a 305. I have one in my DD and it drives great. But when I want to race, I use my Camaro with a 350.

 

you mean like the 301 pontiac used or the iron duke "im on fire" fiero or the wonderfull trans am turbo motor. woot woot that was a screaming 16 second car. how many other motors out there or other parts that have been used that suck.


just cause it's used a lot doesn't mean it's good.

305 might be a good emissions motor, maybe cheaper to produce, something at least caught the attention of GM and I doubt it was performance

 

i ran a 13.03@103mph with my 305, but i've run a best of 12.16@110mph so far with my 360, and i had about the same amount of money in my 305 as i do in my 360, wished i had built the 360 first now....cause with all the extra money i've spent, i could be running well into the 10's. the 360 has much more in it though, once i get a rearend under it i'm not afraid to beat on (rolling into the throttle from fear of breaking another 7.5")

 

following the same logic. if that 7.5" rear was so bad why did GM put it on so many cars


sorry I couldn't refuse cause I'm in a grumpy mood today


also whats the bore x stroke on a 360?
haven't heard that acombo before

 

sbc 360 is usually a .06+ 350

 

well with all that said, how could u say that the 305 is soo bad?? i mean yes in the long run its not as great as a 350, but not every1 has the know how too swap motors or nething so it seems easier to just mod a 305, of course it wont be as fast but its still pretty close

 

A wise man once said, "Those without a firm grasp on basic physics will try to tell you a 305 can be built to be just as fast as a 350."

Same thing goes for "pretty close".

Swapping an engine is no harder than modifying one. It could be argued that it's easier.

I don't have a problem with people wanting to improve their 305. I did it, and was satisfied - to a point. Where I won't agree is if you plan on spending money on the shortblock - at that point, it just ain't worth it.

Put on headers, put in a cam, port the heads - all of that is fine. Bore the cylinders, turn the crank - just not worth it for a 305.

 

Can we sticky that? Your return on investment is, typically, always worse on the 305. When you get beyond bolt ons, it's just a waste of good money. I'm partial to my money.

 

I have a 305 in my TA for the same year My (210hp) and the 5.7 (215hp).
I have headers, I just bought High flow runners and a High flow intake. My 305 runs great......but when I build my 350....I can swap EVERYTHING!
Theres no replacement for displacement! Learn it.....Live it!

 

360 = 4.060" bore x 3.48" stroke.

already got plans for a fully forged 383 or 396 build on another block i have, but it's gotta wait alittle while for me to upgrade the rear to a 12 bolt and a few other things.

 

Well i think ill go with the 350 it sounds better exept for a little extra gas money.

 

My 305 goes fast enough to kill me. What's a 350 gonna do, kill me a little quicker?

Seriously, for me the 305 is fine, plenty of speed/power for what I want, and gets very good gas mileage. Plus, the 'Verts will twist like a pretzel with too much power. If I had a coupe, I'd probably go w/the 350 though. My '92 Chevy truck has one (it's a little thirsty on the petro!).

 

i say that a 305 is in no way better than a 350. like what i plan to do is fully bolt on my 305 then go with a 350 if i can find. i just love the idea that all the bolt ons for 305's will work on 350's! alteast im pretty sure they do lol. i think a 305 is great for a daily driver, but not a race motor. i wish it was though! since i have one!

 

Depends on your priorities.

If your primary concern is reliability and fuel economy, and you only want enough power to do burnouts then you cannot beat the L03. Excellent fuel economy (I was always either close to touching or touching 30 mpg on the highway with mine, but I also had 2.73s.)

I typically find that 305s also have a longer service life than 350s for whatever reason. There are more than a few 305s on this board well over 200,000 miles, and I've seen them roll beyond 300,000. But you're not going to buy the 305 to drive it hard, I guess.

 

i looking to buy and all i find is 305 or 350s too far away. I dont plan on racing and need the best gas mileage, but i think in the long run ill be happy with a 350.

 

Well, the bottom line is that the biggest advantage to a 350 is knowing how much of an aftermarket you have at your disposal. I just switched from a TBI 305 to a carb 350, and there are just so many more performance options and more potential for the 350, which is pretty awesome.

As far as gas mileage, it's really more determined by your transmission and axle ratio. But, given a typical 3rd gen with 2.73s and a 700-R4, I'd say a well tuned TBI 305 will get probably 3-5 mpg better than a carb 350, or even a TBI/TPI 350.

As far as motors, there are L03 (TBI 305) and L05 (TBI 350) motors all over the place. 88-94 GM Trucks, Suburbans, Vans, Caprices, etc. Just check out your local salvage yard.

 

i personally would rather have a 305 over a 350 , a 305 can be built to keep up with a 350 and say if you have a 305 with low kms why waste money putting in a 350 when you have a perfectly good 305?

 

A 305 can be built to keep up with a 350, but for the same money spent a 350 will always, always out-tun the 305.

Fuel economy for the 350 is not that much less than a 305. It's a matter of which you want - speed, or economy. It is completely possible to have a 350 that gets the same fuel economy as a 305 (in "cruise" mode) that will run circles around the 305 in the 1/4, from stop lights, etc., etc., etc.

(I'm tempted to delete any response that says things like "a 305 can be built to keep up with a 350" - guess I'm getting cranky in my old age. . .)

 

Dyno Don gets 26mpg on the highway and runs a 12.80 at the track with his 350.

 

A 305 will always be looked as the crap engine because of how GM handled the entire deal, launched a lot of 305's with crappy cams, exhaust systems etc.


Aftermarket will be cheaper for 350, "generic" 4 inch bore pistons, everywhere, everywhere.

 

305's are seen as a crappy engine it all comes down to personal preference so theres no point arguing about it

 

That's not true. When I changed my stock 305 long block for a 350 long block, and kept everything else the same, my fuel economy improved, both city and highway.

FYI, I later pulled the 350 long block an dropped in a 400 Long block, and added a cam, ported intake, bored TB's, bigger injectors and so on, and milage dropped from 25 hwy all the way down to 24 hwy. Well worth the 1 mpg sacrifice!

-Tom

 

Going from a modified 305 to a stock crate 350 with bolt-ons, netted me a MPG loss, a HP loss, but alot more low-speed torque.

My bonestock 1983 305 converted to TBI, with a dual exhaust, headers, would pull down around 24 mpg in a Van.

 

In some instances, yes. There are several guys in the TBI forum with lightly modded L03/700-R4/2.73 cars that hit 28-30 mpg. My old RS could do with it only exhaust/open element/chip work. I have never seen a Gen. I 350 do that in an F-body. Not that it's impossible, but haven't seen/heard of it.

 

Probably for a few reasons. First, most 350s arent built as weenie as a lo3 are. They just wont get the mileage. Second, most 350s seem to get driven harder, because people think its a 350 it can handle it. Illogical thinking, but its true. The third reason could just be that most people when they start modding forget about MPG. Either go fast or get good mileage.

 

What both 80smetalfan, ljnowell said.

In my case I went from a CFI 305 (which is essentially a "5.0 H.O." long block w/different intake manifold -CFI), to a LO5 350 Long block. IMO, I improved my fuel mileage because of the LO5's lame assed cam and swirl port heads. My stock milage was 24 mpg w/the 305 CFI and headers, and went to 25 mpg with the LO5 350 and the same headers.

When I went to the 400, as I stated before, when I put it in, it recieved a healthy cam (224/234), ported intake, removed "swirl plates", 90pph injectors, Bored TB's, and so on. Based on my 1/4 mile times and trap speeds, I'd estimate that it was producing between 300 and 320 hp, and it got 24 mpg.

I didn't mean to turn this thread into a "what makes good gas milage" thread; Rather I wanted to point out that going from a 305 to a 350 does not -by itself- mean that you will get worse gas milage. I proved this by going from a 170 hp 305 w/a 3.23 rear gear that got 24 mpg, to a
~310 hp 400 w/a 3.45 rear gear...that got 24 mpg.

 

Its not just personal preference. If you are going to "build" an engine. This means machine work, new internals, etc., you are wasting money with a 305. If you have a good 305, and want to go faster, mod the hell out of it. When you get to cracking open the crankcase, do yourself a favor and install a 4in bore kit.