GangsteressRide

I have looked into doing some kind of engine work to my car. But I wasnt sure what to do. I have decided to keep the 305, rebuild it, and try to get more horses out of it, preferably 300. The engine needs to be rebuilt anyway, so why not do it right, and get more horses out of it?

The only thing is, I dont know where to start, what to buy, or what to change. I recently had the trans rebuilt. The rear is stock as far as I know. I was told that I could put 300 hundred horses out of the stock trans and rear without hurting them. Anybody got any imput???

Forshock 85TA

well before the "350" people come in, maybe look into a 335 or so stroker kit, look in the magazines they are always there, of course all the basics of a rebuild. New, better valve train (Do It Once, Do It Right).

There are tons of things that can be searched on these forums too.

Good Luck

ME Leigh

It will be cheaper to rebuild a 350, because the parts cost less.

Forshock 85TA

Hmm thats news to me.... www.summitracing.com

GangsteressRide

But i have a 305, and thats what i have to use. If i had the money to do it better and buy a 350, i would. Getting it bored .30 wouldnt be a problem.

Aredross

Alot of friggen money

Cadillac

Here's a clue:

325 HP out of 305 CID

I've seen some members in this forum claim to reach higher than this number. Search the forum for "305" and "HP" and see what you get.

br()bert

uhm, Doesnt willie have a pretty powerful 305? And i know we have a member with a bigass blower ontop of his 305 making over 600 hp iirc.

ljnowell

You already have a crank, rods, and you will be getting new pistons anyway. If you have to do any machine work at all to the block, it is only about 50 dollars difference to go to a 350. All you need is the block, a core engine.

five7kid

iTrader: (14)

A simple would have yielded plenty of answers.

However, the question was incomplete. Define "300 horsepower" first - gross flywheel, net flywheel, rear wheel - which one? Because which one makes a big difference.

Gross flywheel is what is quoted for all those magazine articles, crate engines, aftermarket products, etc. It's basically a red herring, and you should pretty much ignore such figures. They are obtained on a dyno with headers, typically a "velocity stack" on top of the carb, with no accessories such as water pump or alternator being powered by the engine. In other words, real world irrelevant.

Net flywheel is what the factory has to use by law, and is similar to gross flywheel except the engine has to be powering the accessories (fuel pump, water pump, alternator, etc.), have the exhaust that would be on it if the engine was in the car, and operated by the same fuel induction system including air cleaner as will be in the the car. Claimed horsepower gains that start with factory ratings and then show gross horsepower after inserting their wizbang product (such as the 335 stroker kit) should be ignored (and a case could be made for such claimers to be shot).

Rear wheel horsepower is the most "real world" because it shows what actually gets to the ground. It is also going to be the lowest number of the 3 types of ratings, and 300 RWHP would be very difficult for a non-power-adder, streetable 305 to obtain.

However...

You can get respectable power out of a 305 without having to touch the shortblock. Assuming your shortblock is in good condition. The combination in the sig produces about 245 rear wheel horsepower, based on drag strip results and a few conversion factors applied. Desktop Dyno says it's 362 HP at 6000 RPMs - that's a gross flywheel estimation.

However (and there are always plenty of "howevers" in life)...

If you need to apply a Summit rebuild kit to a 305 bottom end - forget it. You're wasting your money. Find a rebuildable 350 - may not drop in your lap, but spend the time to find one. Even getting a crate 350 shortblock makes more sense $'s/HP-wise than rebuilding a 305 shortblock.

See https://www.thirdgen.org/techbb2/sho...hreadid=255367 lest you think I'm biased against 305's. It's not bias when it's common sense.

And we didn't even touch whether the proposed combination needs to be emissions-legal...

five7kid

iTrader: (14)

Yes, it would. A standard overbore is .030", with .060" being the typical safe limit on a factory block (454's notwithstanding).

.30" is entirely too much to bore any factory small block.

(I realize that was probably a typo on your part, but we do get the "can I bore a 305 to 350" question all too often. 3.736" to 4.036" would be a .30" overbore, but it ain't gonna happen.)

90Firebird550

well my friend re-built his 305 in his firebird, it puts about 390. He went with a stroker kit, .30 over, and little things, upgraded the intake and carb.

ljnowell

Id say a massive cam/head upgrade too, thats a lot of power for a 305!

five7kid

iTrader: (14)

A .30" over 305 with a 3.75" stroke would be slightly over 383 CID.

But, you can't bore a 305 .30" over, so...

Confuzed1

iTrader: (4)

lol....but you can bore it .030 over!

Won't give you a 383 though! Seriously, I rebuilt my 305 and really have no regrets- but that's me.

I know I wasn't pushing 300 HP with it, but yet I wasn't a bit afraid of stock 350's. I've owned 350's in the past that seemed much slower than my slightly built 305 HO....

BUT - I ended up with a 400 under the hood.....go figure.

THEGENERAL

TA5LiterHO

http://www.hioutput.com/tech/343hp/343hp.html

five7kid

iTrader: (14)

Nothing new there. The same work and money applied to a 350 would yield over 400 hp.

Rebuilding a 305 lower end is a waste of performance money.

Period.

Still haven't heard if this needs to be an emissions-legal combination in the end.

Confuzed1

iTrader: (4)

I've heard this argument over and over again. And I'm not saying you're wrong at all 5-7....

Soooo, let's take it a step further.

The same work and money applied to a 400 would yield even more hp....

Do the same on a 454, and you'll yield even more power than that.

Bottom line: There's no replacement for displacement. Easy enough.

five7kid

iTrader: (14)

400 shortblocks are less commonly available. Use of things such as 305 58cc chamber heads, while possible and effective on a 350, is much less so on a 400. A 400 is also externally balanced, which drives up cost and complexity.

454 is a whole new ballgame. Weight becomes a factor. Cowl hood required (unless you're willing to settle for a hole in the hood). Exhaust is a royal pain. Etc., etc., etc.

For a 300 HP goal, no need to go through those hoops.

Confuzed1

iTrader: (4)

I agree with all said above....esp. the point you bring up about about a 400, I know that one first hand.

It all boils down to this in my mind:

How fast do you wanna go, and how much do you want to spend to get there?

300 hp isn't all that much to ask out of a 305, and it's even less to ask of a 350 - and so on.

But I'll tell you what - I'm a lot more impressed with a 300hp 305 than I would be with a 300 hp 350!

That's just me though.

But - as I said above, I agree with you 5-7....you're practically buying the same parts to rebuild a 350 at no real additional cost, so why not?

doc76239

What about the small block 454 crate motor. I'm not sure what the company name is, but I have seen articles in hot rod mag and super chevy. If ya applied the same principals to this 454 then it would make more hps than a 350. May be this person like his 305.

ljnowell

Nothing wrong with being fond of an engine, but he would probably like a stout 350 even more. But as far as the 305, everyone here is just trying to help, it sucks to see someone spend a lot of money and then get his *** handed to him by someone who spent a lot less.

doc76239

What you mean like me spending $700 dollars for my 89 firebird formula WS6 305 TPI with T-5 and 9bolt posi, and then smoking a few 5.0 ponies with about 5 to 7 times the money into their cars. Turnin em and burnin em. It just depends on what you want from your engine and car. If it's a daily driver/ slight street racer, and you want a straight drop in go with a 305. But if ya want to get it to go faster cheaper, now would be the time to up the displacment of your motor. If I spent 1500 on a 305 and 1500 on a 350 ( assuming engine is in the same condition ) the 350 would go faster, with more horspower.

ljnowell

a 350 is a pretty much strait drop in as well.

five7kid

iTrader: (14)

The L69 & TPI guys are in a lot better shape in that regard than LG4 or LO3 guys are. The intake & exhaust of L69/TPI can support a 350 (minor TPI mods needed, like AFPR and possibly injectors), however the LG4 and LO3 exhaust cannot support a 350 (can't support a 305, for that matter). So, the "supporting cast" has to be handled first.

$1500 for a 350 to replace an LG4 with nothing else changed will be slower than $1500 spent to upgrade exhaust, cam, air cleaner and port the heads on an otherwise sound 305. LO3 would also require PROM tuning and injector upgrades, so $1500 probably wouldn't quite cover it.

forums_suck

I did a cheapo rebuild on my 305 in my 83Z
edelbrock rpm manifold
comp 268h cam
flat top cast pistons
I used the stock metal shim gasket,did some porting on the heads,just basic gasket match and cleaned up the short side radius.
i used some cheap headers,and man what a difference really woke up the engine.It wasnt stupid fast but it was a blast to drive.The machine work consisted of having the block cleaned and punched out 30,crank polished.
This was 10 years ago now,I think the pistons cost me 80bux cdn.
If i had to do it again though id get one of gm cheapo crate motors,Plenty of power and a good foundation for later upgrades

jrg77

Could it be said that the main reason one would build a 305 is so they don't have to go through the extra expense of upgrading the transmission and rear end for the additional torque?

Jason

THEGENERAL

umm what do you mean upgrading for additional torque ???

if you are going from a 305 to 350 the transmission and rearend will handle alot of abuse before it needs upgrading..

thats not a good reason to build a 305 thats a bad excuse ...LOL

jrg77

If the transmission is an auto sure, but if it is a T-5 well...

$1300 for an engine buildup beats $2600 for an engine AND trans.

Jason

THEGENERAL

there are lots and lots of guys running a t-5 with a 350 that are running in the 300+hp range and not having any problems with thier transmissions at all....

jrg77

I thought running a T-5 with a 350 was one of those abominations that 3rd gen owners don't do. From what I've read the actual Case can split apart. Are these guys just choosing to let the thing break then upgrade?

I haven't done either so I am not claiming to be an expert at all. I agree that building a 350 preferrable to a 305. But if you just recondition the rods and crank, get new pistons and call it a day that is a whole lot less than a 350, even if it is just the fact that you don't have to buy a sued one to start with. From a purely short term cheap route the 305 is sufficient.

This doesn't even consider that according to this board there are NO good stock 350 heads, while the '416 and '081(?) are workable with a homemade port and polish with bigger intake valves with a 305. Locally that's about $300 vs. $500 for some new vortecs (which the car did not come with) that require a new intake manifold to boot.

It is better to build a 350. But if it means that you don't get in the game because of all the "might as well's" then build the 305, and just plan on more later.

Jason

THEGENERAL

this is a never ending arguement for sure..LOL

if your going to do the work to a 305 then youd be alot better off doing it to a 350 ....there is no replacement for displacement... as for the heads issue yes you are correct to say that there arent very many good heads that came stock on a 350 but thier are alot to work with expecially when you look at putting a set of 305 heads on a 350 with some work done to them ....not only will it give you better compretion but you already have the heads if you are going from a 305 to 350.....

look at it like this if you are just wanting to get your car moving and dont have much funds yes rebuild your 305 to stock and go ....but if you want to build something for performance then its rediculous to build a 305 when everything you put on it you could have put on a 350 and made more power....

ljnowell

Its ridiculous to rebuild a 305 period. There are no excuses for it.

90-irocdx3

iTrader: (4)

i think 335tpi has a nice setup he is doing 13 second quarter mile.

ljnowell

And with the same amount of money invested in a 350 he would be running faster. Sure its nice, but its still a waste.

GangsteressRide

TOO MUCH COMPETITION!!!

Im getting too many awswers here. Ones arguing 350, ones arguing 305, ones arguing 383, and another doesnt care.
Ok, what are the benefits of rebuilding a 305, or a 350? Which will be cheapest and best, and not overkill. Yes, we have to be emmisions legal. I just want some respect while driving a camaro. Smoke some Neons and Civics or somethin."



"It's a GM, I don't ask questions"

Air_Adam

If I wanted a 300hp 305, this is where I would start:

- Bore the block .030 and have all needed machine work done
- Port a set of 416/601/081 heads, add 1.94 and 1.6 valves
- Flat top pistons
- Perf RPM manifold
- 650cfm Double Pumper 4bbl
- 1-5/8" headers from Hooker, Hedman, etc

I dunno about the cam though, never been good at cam stuff.

jrg77

The easiest way to answer your question is how cheap is cheap to you? Given a dollar amount the answers get easier.

It also helps to know if your car has a carb or TPI.

There's a tie for absolute cheapest. You can rebuild your engine or buy a crate 350.

For a few dollars more is a 383 which is just a 350 with some changes on the internals. Depending on how badly you want to beat the 4 bangers or how much work they've done on them will determine how much more expensive it will get.

Under $1000 work with what you've got. You may get to 300hp you may not.

$1000-2000 get a 350.

$2000 and up get a 383.

Hope that helps.

Jason

ljnowell

There are no benefits to rebuilding a 305 over a 350. No matter what you do to a 305, the same amount of work put into a 350 will be faster. Period. No doubts about that. A 350 in need of a rebuild wont cost very much, and will cost about the same to be rebuilt, if not a little cheaper (cause of the pistons). The power output will be noticably greater, and it will take to later mods much better. In short, anything a 305 can do, a 350 can do better. No one here likes to insult, and dont take this as one, cause it isnt, But building a 305 is stupid. All the way around.

GangsteressRide

I was told the carb on my car cant be changed without doing serious work, because its the electronic controlled Carb, "Mechanics Nightmare". So thats all ran off the computer. I dont know whats involved changing over a carb on this car, but I was told you cant without doing serious work.

Money spending wise, I would say like 1,000-1,500. I just have to know exactly what to get, how to tune, and stuff like that. Also why was the one guy saying you cant bore a 305 .30 over? I thought you could. Thanks guys for helping so far, im new at this stuff.

:rockon: :hail:

jrg77

The correct term is .030 over, not .30 over.

With $1500 max don't even think about swapping to EFI. You just want to replace the stuf under the carb. A basic 350 should suffice. The $1500 will buy a new crate engine. You would still have to pay the mechanic to replace your current engine with it, unless you do it yourself.

I hope this isn't your daily driver, cause it will be a couple of days, and your mechanic doesn't really sound interested.

Jason

ScottyRS

iTrader: (2)

I'm sure that GangsteressRide is well aware that a 350 can put out much more power. But he didn't say anything about putting a 350 in the car. Maybe he has a great 305 thats still running strong and wants to rebuild it and put some work into it to make it a kickass engine, instead of being a lazy *** and just dropping in a 350 like everyone else and their mother does. I salute him for wanting to build a bitchin' 305 and if I had the money I would do the same. Because where's the challenge/fun in building up a 350? Besides, it's gonna be very rewarding to snuff out some of you 350 guys with lil' 305. GangsteressRide... you're gonna have to redo the entire engine. Get some World Torquer or L98 heads a new valvetrain and exhaust and you can figure it out from there.

jrg77

I'm willing to bet that GangsteressRide is female.

Avenger007

take cadillac's advice and check out that webpage. If you have $1500 then your set for 300+ hp.

L31 Vortec Heads $600 Assembled
Edelbrock RPM intake $150-200
750 Holley $150-200
Comp Cam $100-200

spend the rest on exhaust.
Youll be good for 300hp at least
but you need to grab 3.73 gears and a decent stall so add another $300-$400 at least.
(Also consider upping your wires ($60), ignition ($150), and fuel pump ($150)
worst case is about $2000.

Now consider finding a 350 Block for $300-600, then buying decent heads, intake, exhaust, and carb and doing the complete swap. Youll need a new knock, and computer. In the end you have more oppertunity down the road. But you spend an extra $600-$1000 minimum and lots of time just to get around the same results. The main difference is that the 350 isnt already there. So you have to consider everything needed for a swap before looking for hp figures

I personally did a 350 swap instead of 305 build-up and so now considering heads and bottom end is easy since Im not debating 305 or 350. I know its not much help but thats my personal account. Goodluck

five7kid

iTrader: (14)

It's not that serious of work, but it is completely unnecessary to get 300 HP out of a 305. In fact, it is money spent that won't contribute towards getting to 300 HP.

Vortec heads (and the required intake manifold), Holley carb (as stated above) are not at all needed to get you there. The very first step has to be exhaust. Assuming you need emissions-compatible parts, that's going to run about $1000 (maybe less, but you can spend more) right there. It won't get you to 300 HP, but it is needed.

The air cleaner (small, but important, detail), assuming you have an LG4, which is most likely. You need a dual snorkel air cleaner, either a factory-type one, or one that's fabricated. An open element will do, but it is less desireable, and is not emissions-compatible.

Then cam.

Then head porting.

If any money needs to be spend on things like rings, bearings, or pistons for the 305, cut your losses and go find a 350 to rebuild. Seriously.

The sig in my original post is a 350 GFWHP combo on desktop dyno, performance indicates 250 rear wheel horsepower. With the stock computer controlled carb.

berlinator

http://www.hioutput.com/tech/343hp/343hp.html
this arcile can help you find some ideas

i know the 305 Vs. 350 arguement could go on forever but seriously about the whole "no replacement for displacement" i dont believe its entirely true, at the same time yes i agree bigger is better but at the same time i think its quite possible for a fully tricked out 305 equiped with low compression pistons, a turbo or two, or even a supercharger would kick some serious @$$ and be able to beat out alot of lager displacement engines (given that they dont have the same amount of work done as you, in which, yes displacement would previal)

besides all that, if you really know what your doing anyone could potentially make some boss power from any engine dispite displacement.

ljnowell

If its so great of a 305, why would he need to rebuild it? And since when does installing a 350 make you lazy? Its the exact same work to do either, THE EXACT SAME!


Why would you want L98 heads, are you installing a blower?

Orr89RocZ

iTrader: (20)

what about LPE 211/219 cam, and superram on World S/R's torquers with minor port job. should make close to 325 hp if not more.

fully upgraded Large runners and ported base setups should easily flow tons of air for the 305 cuz its designed for it LOL. Should be easy to make 300hp+ with 210/220 cam from comp cams and those World heads, but i guess other heads can be used as well like L98's vette heads. That be nice mid 13's or better combo for sure.

THEGENERAL

man you flip flopped in that statement back and forth so much im confused,.....LMAO
you went back and forth 4 times ...LMAO..LOL