Thread: my 305 putting out 304 HP

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Nothing wrong with a 305. Got one in my 78 firebird and it'll scoot. Not as strong as what you've got...

mine is .060 over, stock heads, dual-angle grind, Comp cam with .454 int/ex, 290 duration, HEI, and (get this) two barrel intake and carb. It gets 18 MPG @ 80 MPH, and is exremely reliable. I had a 2.56 rear end with clutch limited slip, but it wore the tires too badly ( daily driver ) so I swapped it for a 2.41 open rear diff. @ 65 MPH I can drop it into second with no fear, and grab a car length before the other guy knows what hit him. Got a 350 turbo trans with a stiff shift kit, it'll gain a car length when it shifts from first to second.

The wife had a 318 in her 86 dodge diplomat, with similar build, but the 305 in the 'bird would smoke it everytime.

So good to hear positive things about the 305. I swapped a 305 into an 89 Astro, but I haven't got the bugs out of the setup yet. That's been frustrating, to say the least, and right now I need to walk away from it for awhile.

Your all right in saying there's nothing wrong with a 305. Not as strong in the bottom end as the 350, but they can be made to scoot.

Would it be cheaper for me to build a 350 and just put that in there or just rebuild this 305 with a better crank, pistons, basically the whole engine? What is the most you can bore one out to and still be completely safe without worrying about thin walls or heating issues?

Originally posted by FMXhellraiser
Would it be cheaper for me to build a 350 and just put that in there or just rebuild this 305 with a better crank, pistons, basically the whole engine? What is the most you can bore one out to and still be completely safe without worrying about thin walls or heating issues?

You will have time and a lot of money into somthing that a stock 350 would make. to answer about the boring of cilynders, I think .060 is as big as they can saftly go, I may be wrong on that tho.

You don't want to go more than .060 and even then the walls will be pretty thin. I bored mine that amount and had no problems with heating, but I've heard others saying they have. I kept and built my 305 because thats what I had. To be honest with you and even though this engine hasn't given me to many problems, I would go with a 350 or 383 on my next engine.

I've always bore mine to .060, and lots of guys like to pop a gasket when they hear it. Never had a problem, even when I lost the fan belt, and it ran hot enough to melt the sending unit for the temperature guage! ( did crack the head though )

I hear you can punch them .090, but I wouldn't.

The only problem I have with mine as far as temperatures are when I'm waiting in line for awhile. Since I don't run a mechanical fan because of clearence issues, I run two push electrick fans in front that I've set at 200 degrees to go on. Cruising I have no problem as my gauge stays at 180 all the time.
I've heard of people who have bored .080 over but .090 you wouldn't have any cylinder wall left and you would have to sleeve it. To go to all that for extra cubes not worth it.

Hmm well if I get intake manifold and carb, etc from Edelbrock and I decide to build a 350 next then I can switch that straight over right? My dad keeps saying that if we rebuild he wants a 350 instead. He had a 305 in one of his cars which I think was the El Camino since he said he had the choice of a 305 or 307. He said the 305 was nice and ran strong and long but not good for power at all. If I start looking for a 350 block soon then what should I start looking for? Maybe that cheap plain stock GM crate one for like 2000? Or maybe it was 3000 I forget. Then get that and upgrade it. Or should I get a block and get better pistons, etc and still be able to build a motor from a block for about 3500? Oh and that doesn't include the carb, manifold and whatever else I can use off the 305 since I will have that too if this carb and manifold will switch over.
Thanks again and sorry to rob the thread. I figured I'd ask it while on the subject.

Oh and say I have a 1985 chevy truck and then I get a motor that is 35 years old or older (since if that is the case then no inspection but anything newer than 35 needs emmisions, etc inspection) then do I still need to get inspected or will they look at the motor being the year? Or what if I buy a block off something and the motor is completely different? See what I mean? I dont know all that law kind of stuff so wanted to ask.

Hi i am 17 and i am thinking of buying a 305 tbi camaro...i have done 3 years of research into these types of motors...i have found the most reliable power adder for the 305....taking a 400 crank and balancer and putting it the 305...!!!! i know it sounds wierd...but you should still get resonable mpg but with stroker torque....I have heard of these 335 motors seeing 400hp!!! (with a four barrel carb) also holley offers a 670cfm truck throttle body...for you tbi guys this is a wise investment. Aslo the gm performance parts catalog has a vortec tbi manifold...with vortech heads an lt4 hot cam and some good headers this engine should run low 14s and high 13s in a 4000 lb car...i have a few links that might be helpful....LOVE THE 305 HATE the hype about 350's....who cares everyone has one.
http://www.goingfaster.com/spo/modthel03.html GREAT SITE....AND GREAT FORUM!!!

Yeah 305's are nice but then again reason everyone has a 350 is because they are cheap to build and all the money you put into the 305 can be put into the 350 and make much more HP and Torque.

HEY FMX, if you can find an 84 Caprice Classic wagon it should have heads # 14014416 80-85 yrs.,58cc,1.84/1.5 valves,7exhaust holes And should have the factory aluminum q-jet manifold. Thats the 305HO that came in those boats and they have good ' street ' power. Should find them in junkyards everywhere. That would pic up your compression and HP and be able to use any pump gas ya want. I know, I got one. I took the heads & manifold off to put on an intermediate 350!! 305 or 350 there is an argument to be made between either torque or hausepower, depending on what other goodies are there. Whatever floats ya boat.

I love the 305...there isnt anything i would rather build. To me a 305 is kind of exotic. I mean money aside (because it will cost money but not as much as it would to throw a beefed up 350 in) a built 305 or 335 could out perform any tpi 350 or even run circles around a bolt on lt1! I know it has its limits but for street/strip power the 305 gas miledge and performance cant be beat. And to anyone who says an LS1 can get the same or better gas miledge....WRONG. I have driven a 350 hp LS1....get used to refilling twice a week. LS1 is a great motor but lacks on the lower end. I would prefer an older engine.

Oh and another thing for us 305 guys... a lot of LT1 engine parts can be used for performance such as the LT4 hot cam. Keep on resisting the 350 even thought it may seem purty.

shevy, thanks a lot for the info man. I will look for one of them around here. Sounds like a cheap and good idea.