Thread: hosrepower 305

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whats the best way to get the most horse power out of my 305? with breaking my wallet? just mainly things like adjustments.

it runs really good. better than we suspected after rebuilding it. i don't know if you all will beleive this but i have gotten it up to 120mph. thats good from what i have heard. the motor that was in it before was a 350 and it was torn up inside. the intake manifold had a crack so the old owner did not fix it and it screwed it up. so one of these days i will rebuild that one too. but why do you say "techinspector1 DO NOT, I repeat DO NOT spend over $50 on this lump. The 305 was Chevy's redheaded stepchild. If you want more horsepower, sell the car and buy something with a 350 in it."?whats wrong with em?

Did you also say you rebuilt this?

What do the heads on the broken 350 look like?
What have you got for exhaust, cam, carb, intake now on the 305?

" Speed costs money. How fast can you afford to go?"

You can prolly pick up a used running 350 for under $500. That would be the cheapest what to make the 305 go faster...replace it!

the 350 will bolt in, but if you have a single exhaust, the Y-pipe is a bit wider on a 350.

if u dont wanna spend the money, gears and nitrous sound good to me, save ur money and dump it a 350. If ur bent on making the 305 work, cam change possibly, carb, intake, distributor, tune up. In other words, it wont be cheap so start rebuilding.

the heads are just filled with crap. so were the exhaust manifolds and the intake manifold was cracked and filled too. i already know that most 305 parts are compatible with 350's or is it the other way around?
but exhaust i'm not sure. ithink that thats still stock. i have a quadra jet edelbrock carb. cam? and distributer? i'm not sure.

speed took a downward slope but it wasnt that steep. time im not sure. but gas mileage SUCKS severly what can i do to better it?

the heads are just filled with crap. so were the exhaust manifolds and the intake manifold was cracked and filled too.
-crap...as in cow manure? cabon? JB Weld? Mud? Depending on what it is(was) means it may be removeable, and you should know what it is so taht you don't get it again!

but exhaust i'm not sure. ithink that thats still stock. i have a quadra jet edelbrock carb. cam? and distributer? i'm not sure.
----before you can diagnose what is wrong with your current engine, and therefore decide what to do first, next, etc, you'll have to know what you got! -Edelbrock makes many carbs...Quadrs-Jet is a trademarked name for a Rochester made carb. So you have a spreadbore 4 barrel by edelbrock? What numbers are on it - see Streets for tath, he may be able to identify it, or check the summit or edelbrock sites. Most likely a 650 CFM carb with vac secondaries...but there are other possibilites. It may not be set up right. Did it come on teh 305 or did you move it from teh 350?

Cam...stock or aftermarket, if aftermarket then what cam? The cam is the brains of the engine - it will determine what RPM youwill make power at, and to a lesser degree what you should think about for intake, exh etc.

As to the bad MPG...check the plugs, timing, cap and rotor...does it start and run OK, idle OK, etc? If the exhaust is stock you will have cast iron 'log' style manifolds and a Y pipe and 1 tail pipe with a catalytic ocnverter in it (most likely...what car is this again? what year?)

You pulled the 350 and put in teh 305? Where'd the 305 come from (what car)?

By MPG sucks...what is sucks? 15 is OK, 20 is good. 12 is bad, (for a normally driven camaro with a 305) BUT that depends on other factors - a 4x4 truck with 4.10 gears and a load of engine blocks in teh back might get only 8, so 12 would be GOOD for that vehicle...with a 305. If youare diring it with the secondaries open on the 4bbl, or the powervalve is mis adjusted, or timing is retarded (or vac advnace inop) then you will get bad MPG.

We need MUCH more info than you are giving us!

horsepower 305 is right up there with military intelligence!!! Scrap the thing and drop in a big inch motor. The only substitute for cubic inches is more cubic inches.

ok as you all can tell i am not very fluent in motors but what i do tell ya'll is what i know i don't know that much about the engine this is my first truck i'm only 17 looking for a way to make my truck better. the crap inside the engine is removeable but not without a lot of work. it came from water getting inside it. i'ed scrap it if i had the money to get me a better one but i don't so this has to suffice the rest i really don't know about. the timing IS off a little or so i beleive because both my grandfathers build engines hotrods from scratch (no lie) and they both said so. the carb is aftermarket but we did take it off the 350 and put in on the 305 the 305 came out of an 85 van. it was the best thing running for the price. i geuss the gas mileage is good. i just didnt realize it. i get about 14 mpg give or take a few. its duel exhaust it doesn't y off the carb has 4 "holes" in it and the cam i don't know about it is an 82' chevy silverado "305". its not 4x4 i wish it was in a way 4bbl? powervalve?i don't know what your talking about. vac advance inop?well thats all i can say for now so later!

Let see if i got this...
you have an 82 silverado pick up with teh 305 from an 85 van?

You moved the 4bbl carb from teh 350 that came in the Silverado, and put it on teh 85 305?

You know little, but you can learn. So how did you swap teh motors?
If your grand fathers build hot rods, and 'know' the timing is off, why have they not helped you set the timing?

14 MPG is not unreasonable for a pickup. The carb from teh 350 could probably used rejetted and cleaned and set up for the smaller motor.

On your distributor, there will be a silver cone shaped device sticking out the side of it, with a hose on it. this is the vacuum advance. to set timing you will need a timing light (read the directions with it or ask Grandpa) and then you disconnedt this hose to the vacuum unit, plug the hose (golf tee, screw, vice grips, etc) and then check timing with engine warmed and idleing at right speed (650 rpm most likely) in park. set timing - have grandpa help, he'll know how if he has built hot rods. you may want to advance the timing 1 or 2 degrees. DO NOT go by the specs on teh sticker under the hood of the truck - you need the specs for an 82 305 van motor!!!!!!!!!!!!!!!!!!!1

if timing is retarded that will hurt mileage.
if the carb is set up for a 350, that may hurt mileage a bit too and you will run a tad rich, not enough to foul plugs.
The gearing for a 305 is likley diff than that of a 305, so you are probably lacking in acceleration and therfore drive with your foot deeper into the gas, hurting mileage more than anything else!

If the vac advance hose is NOT hooked up right, that can hurt mileage too. you say you moved carbs...why?

streets..he says aftermakrt carb from 350 was moved to 305...
i would think TBI on trucks was late 80s item..not positive on that tho.

i would suspect cam is stock 85, and should be replaced! perhaps the 350 cam into the 305? what is mild for 350 would be more potent in a 305...cost is gaskets and time. price is knowledge, a bit lacking here.

i have to wonder howthe engine swap was acomplished when he has no clue as to exhaust, or even timing....

Are the 17 yr old ricers this far, umm, behind? no wonder their cars are s l o w and funny lookin and weird soundin'.

you see my dad helped me move the engines. no were not that far behind i just am. i have not been into motors all my life. on my carb it says the logo quadra jet. whats TBI? my dad did say that it was running rich and i didn't know what he meant. i haven't been to my grand fathers houses in a long time. they've come over but didn't feel like messing with it. Screamer, explain this more please...."i would suspect cam is stock 85, and should be replaced! perhaps the 350 cam into the 305? what is mild for 350 would be more potent in a 305...cost is gaskets and time. price is knowledge, a bit lacking here."i don't get it. during the swap, i mainly hooked up parts underneath and a few above. my dad and brother-in-law connected and timed everything. i don't think they have a hot tank. how can i change the carb settings to a 305?

OK, TBI stands for Throttle Body Injection. The cam is the shaft in the middle of the engine that opens the valves. A 350 cam is higher lift because it has to allow greater air/fuel mixture flow to the cylinders. However, the factory 305 cam from the 80s sucked. If the 350 cam is still good, change it into your 305. If your 305 is computerised, it should change the settings itself, to a point. You may have to swap the jets if they are to large. I hope thats it.

Rich/Lean - there is an optimum ratio of fule to air taht an engine needs. A bigger engine, bigger mans it pumps more air, needs more fuel. So you moved the 350 carb to the 305 and you have a carb 'expecting' to feed an engine about 12% larger than what it is feeding.

Add to that, the camshaft - it controls when teh vlaves, open, for how long and how far. An engine is a system- every part has to be designed to to produce similar results...meaning, a big cam (high lift) is used when you have the intake, carb and exhaust and heads designed to flow the air the cam is allowing in to the engine. Put THAT cam in your engine and it may run, but not very well (as in 'right' or 'efficient')

Generally speaking, everything is a compromise... you can have horsepower or fuel economy, but not lots of both. you can make lots of horsepower, but the most is made at high RPMs, not good for street use. A cam can be made for low rpm torque (good for trucks, towing and low rpm use) but if you wnat to race a Vette, you'll lose if this is your cam choice, BUT you'll be able to pull a house off it's foundation.

larger engines have larger cams - more lift and or duration (time valves are open as mesured in degrees of rotation of the engine). So a stock 350 cam in a stock 305 will improve performance overall - hore HP, more torque. Possibly more MPG..that depends on many other factors. All else being equal, if you engine makes more HP, it takes more fuel to do that. BUT if you make your engine more efficient (more HP from same size motor) then you can, in theory, use less gas pedal to drive at teh same speed so you may see better gas mileage...

You moved a motor from one vehicle to another, granted both chevy's, but different years, engines, etc. You should double check that all the vac lines are hooked up right.

Jets...the little items in a carb that control how much fuel can flow. the larger the jet (the bigger the hole in it) the more fuel can flow. The carb came from a larger engine, so it is jetted to flow more fuel than you need now. Also, teh rear end ration and or trans rations may have been a factor in jetting from teh facotry too (federal rules on emmissions and MPG are in effect here)

You know something? if (certain)people had unlimited time and unlimited money, a lot of the world would be set right. Hmmm, maybe thats what they origionally invented the welfare system for!