I have a 305 engine i want to do some small upgrades too. i understand these arent the greatest engines to start off with, after some searching around on here that has been pretty much stated atleast 5 thousand times.

putting aside the fact its a 305 and most people dont like it, its what i have and its what im working with. i dont have the time or tools to perform a complete 350 swap with all the bell and whistles. that being said lets move on.....

my idea starts with an 89 305 long block. around 102 thousand miles on it. my ideas are as follows,
stock heads
stock bottom end
214 224 flat tappet cam
performer rpm intake
700 cfm holley dual feed double pumper
stock transmission
stock rear end non posi 2.73
long tube headers

how well would that whole application work out?

IMO you should stay w a roller cam.

305 motors are great if you want a v8 engine that gets great mpg...but just not for killer hp.

Id pick a cam carefully...watching the lift numbers....keep short duration with all stock stuff.

Smaller cam is fine...but no stupid off brand cams. Lol

Carb is too much...wayyy too much. Look at a qjet or 500-600cfm carb tops.

Upgrade timing chain and the correct springs. Then...good exhaust system.

Stock torque converter and gears will kill the acceleration completely...FYI.
Good luck!!

113 heads and an LT4 hotcam should get you in the 250-275fwhp range. Maybe more.

ok well lets say i hop it up some with some head work. 1.94/1.50 valves, porting and bigger springs?

how awful would it run with a 700 cfm carb?

i may upgrade to a 2600 rpm stall for time being since they seem to be pretty affordable on my budget

what rear unit would suffice? i want to go with like a 3.42-3.73 ratio

is there really an issue with going to 2.02 1.60 valves? if not i do have a set of those i could use

decided to keep the cam roller for reliability

2.02 valves will hit the cylinder wall on a 305.

A 305 only needs a 500 CFM carb on it (unless RPMS will stay above 6500). And with stock compression no need for a double pumper. A 500 or 550 CFM Vac secondaries is all you need. A 700 CFM will bog hard core. If you are idling around and NEVER touch the secondaries no problem but open them up and she will fall on her face and flood bad.
Keep a roller cam shaft but i would step up a grind from stock. The stock heads just suck and there is no porting you can do to make it a lot better. SR 305 torquer Iron heads will do that engine great. If you are using stock pistons get the thinnest head gasket you can to bump the compression a tad.
For gods sake put some 3.42 gears in her! and you can use your stock converter. A stock converters stall will rise with power input... not a lot... but a little.
So, some good heads, the correct size carb and good exhaust and that little 305 will honk just fine.
Dont forget to use a good set of plugs (I like the E3's) nice warm coil, and a 8 mm set of plug wires and a brass cap and rotor and you will be on your way.
you have to remember... if you skimp out on ONE thing... the rest of the parts are just worthless. Many people do not finish in to the end and buy a crap part to save 5 bucks and it is then all for nothing. Package deal.

on a side note we have used 202 valves in small bore engines... you have to re leave the cylinder wall for the valve head. Tricky stuff and I have destroyed my share of engines doing that. Some will take it and others wont ( I say that because there is NO way I messed up )

A 700 cfm vacuum secondary will not bog a 305 in the least way. When you get up to the 350 HP range, you NEED a 700 cfm carb, don't care what those crappy CFM calculators say. The vacuum gauge on an engine running at WOT tells the story far better. The 340 HP 305 engine in the Vette loves its Quick Fuel 700, gets better mileage with the Edelbrock 1406, but for power the 700 VS is where its at.

You have a vette w a 305? I have to say its the first one I've heard of. I'm not making fun, I've just never heard of anyone putting a 305 in a vette before.

you need to read everything before flying off and thinking you know all..... he was going to put this carb on: 700 cfm holley dual feed double pumper. not a vac 2ed carb. and yes a vet with a 305?
I just sayin

I would start with upgrades that can be used on a 350 as well. Rear gears, headers, intake and cam. 300

Ive seen a 650DP do low 12's on a 305 making ~325ish hp. Wasnt what most would consider streetable, required a lot of gear, converter, and a huge cam. A stock bottom end would probably come apart at the RPMs that motor turned when it raced, but it was mostly stock 416 heads and a 650 DP.

Carb cfm ratings are kind of weird anyway. 700 is probably a bit much for a 305, but theres no need to go all the way to 500 cfm, even with a double pumper. Theres a lot of voodoo in "cfm" ratings. Just because something is rated at a certain cfm, doesn't mean it wont flow more than that. It just affects air velocity through the venturi, and more velocity is usually easier to tune.

certain 'vettes around 1980-81 had 305s;i think they were"california emissions"4-speed version

Well I guess a California 305 vette is definitely rare... May not be desirable, but rare lol.

I may have missed it, but are you TBI or TPI?

A cam with 214/224 duration @.050 is just a tad large for a driver 305. Also the high rise intake doesn't do well either. About a 265 cam and regular performer intake with a 570 Holley carb, and 3:42 gears will liven it up a BUNCH. I'm running a mild built 305 in my Daily driver S10 Blazer weighing in at 4000#'s with me in it. It just dips into the 14's in the mid 90's. .030 over 305 with stock lower end, 9.5:1 flat tops, double roller timing chain, stock 416 heads, Crane .442/.465 lift cam, pushrods, and stamped roller-tip rockers, Weiand action plus intake, Holley 570 street avenger, Mallory HEI, shorty headers and true duals, 700r4 trans and 3:42 one legger. Daily in town gets me about 16mpg, 19 on a road trip. consistent 2.1 sec 60ft.

You're right, but youre not gonna make power with a 305 unless you spin it up. just the fact of life when it comes to small displacement. Torque x RPMs x conversion factor = horsepower

You're trying to go easy/cheap, and that simply WON'T net you the results you're looking for. There's a reason why everyone 'moves up' to a 350 (or bigger) - because it's easier to get results out of them. You're really limiting yourself with a 305 if you're trying to make something capable of respectable numbers. Like mentioned before - it's been done with a 305, but I'd guarantee you it's way out of your budget that you're trying to keep.

Want to do things right and NOT waste money? Put it into the rest of the car. Get a better gear ratio in, and sink some change into the suspension and transmission instead. People focus so much on making power and forget that power is worthless if the transition to the ground is poor. especially on a car with higher mileage where there's a LOT of worn out parts to replace that will help the car move off the line quicker. I'd get a quality converter, a transmission cooler, etc. That way you haven't wasted any money on any specific build path and it will give you some time to plan things out in any direction you want to go.

That's my two cents. My logic is you should never half-*** anything because you're on a tight budget. Either do it right the first time while saving your pennies and being patient, or don't do it at all.

I agree with everything he has said.I want to add the one way to cancel out any air flow issues with these 305's and because it forces you into a smaller cam is to turbo it.It would be a natural step because turbo engines like smaller cams and it should go hand and fist with a game plan for a rear end gear change too because with a turbo you don't want to go too deep in a gear ratio either.I think that is worth considering.

To the O/P.BTW-I don't hold anything against 305's.I set back and cheer on what anyone else would consider a under dog.A turbo set up as long as you keep it reasonable in the boost is friendly to a stock bottom end and is also a friend of a lower compression ratio/lower rpm.The turbo systems isn't as hard on engines as a nitrous system would be.Depending on the amount of boost set by a waste-gate,is considerate of the octane gas you use.More boost,more octane.And it is sort of a on demand system.Seems for a 305 it is a ++++++ all win situation.

I agree thats an excellent use for a mostly stock 305. With a turbo the power is only limited by how much boost you want to run and how well you can tune it. If you blow up a 305 who cares? Get another one. Eventually he can move up to big boy parts and some expensive heads and block and rotating assembly, but you can make the stock stuff live quite a while if you take the time to learn to tune it, and its better to grenade cheap stock 305 stuff than expensive stuff. Save all the expensive aftermarket stuff for after you have learned how to tune it all.

To the OP, this is a really nice, informative video done by zz3astro on youtube if you'd like to go this route.