Seriously thinking about 305 upgrades

I've posted about this a long while back but i'm actually seeing this as a possibility. I know someone who can do it cheap. I figured i have an engine that works and if i can do it for cheap then why not do some mild yet effective upgrades? I'm up for the learning experience anyway, despite the bad reputation this motor has when it comes to response and power. :biggrin:

So what i want to know is what exactly should i do? I was thinking replace the carb, intake, and camshaft, but what exactly should i get? I remember Silicon or somebody else might have mentioned a specific cam i should use. I think whoever it was said i'd be happier with a mild cam? (I'm good with that economy-wise) but also a certain (mild) cam would ensure i don't actually lose power when it comes to low end torque, and this engine would be NOTHING without that. So what should i use for a new intake/carb setup? Would i be ok with the stock heads or even exhaust headers too? Like i said i think i want this to be a mild, yet noticable upgrade.

I believe the major reason these engines lack power is that the bore is too narrow to allow enough valve space for the length of the stroke. Intake and carb may help, but I don't think you'll get enough of a difference to justify the cost. Honestly, you'd probably be better off swapping in a salvaged 350 and leaving it stock.

quadrajet carbs may be disrespected but i would stick with the e4me. i may be wrong (please correct me if so) but i recall reading somewhere the e4me quadrajet flows 600+cfm. my buddy always had "toys" his first car was a 72 chevelle, his old man had a 56 chev belair with a m22 4speed and a 305 from a camaro. they dumped crazy money into the engine, cam, heads, complete low end and after all the work the engine was still lacking. they eventually dumped the 305 and picked up a 327... if you are willing to tear apart your engine and be without your car long enough to get it back together why not go with a 350?

no way on a 305cu....waste of your money...

the 350 cu with the engine work can be do able and worth the effort, with results.

305s are worth nothing and most machine shops will tell you this.The Quadrajet carb,most peoplw walk away from and do not know they are very simple and easy to rebuild.If looking for a 350,lok into a good crate engine.Edlebrock,Jasper and GM have them with a warranty on them.Rebuilding an engine these days is not worth the time.

Dude... i was wondering the samething about 6 months ago and went and just did some upgrades and already regret doing them... i rebulit my carb(quadrajunk) and did a intake and some other minor things and other than about 1 mile more per gallon i got no more power... i am planning on upgrading to a 350 before summer but from what i hear its hard to do when your caprice is your daily driver:lol: any way if i was you stay away from 305's that what every one says!!!!!

quadrajet carbs may be disrespected but i would stick with the e4me. i may be wrong (please correct me if so) but i recall reading somewhere the e4me quadrajet flows 600+cfm. my buddy always had "toys" his first car was a 72 chevelle, his old man had a 56 chev belair with a m22 4speed and a 305 from a camaro. they dumped crazy money into the engine, cam, heads, complete low end and after all the work the engine was still lacking. they eventually dumped the 305 and picked up a 327... if you are willing to tear apart your engine and be without your car long enough to get it back together why not go with a 350?

Yeah that might be true. I even know someone with a 350 they were selling for $100 so i hope they still have it. Of course it needed to be rebuilt though. I just thought a rebuild would be too much money..but hey it'd be a good engine that i could dump into almost any GM RWD car so its very flexible.

Yeah that might be true. I even know someone with a 350 they were selling for $100 so i hope they still have it. Of course it needed to be rebuilt though. I just thought a rebuild would be too much money..but hey it'd be a good engine that i could dump into almost any GM RWD car so its very flexible.

get a bad 350 motor cheap. then get the motor worked on to your specifications.. why pay more for a good 350 if your gonna do some power modifications ?

when its all fixed up pop it in..little down time ..

quadrajet carbs may be disrespected but i would stick with the e4me. i may be wrong (please correct me if so)

Those Q-Jets flow around 750 CFM

Those Q-Jets flow around 750 CFM

wow, a bit more than i thought

wow, a bit more than i thought

how is the 305 with a quadrajet gonna handle 750 that is too high..

its 600..

how is the 305 with a quadrajet gonna handle 750 that is too high..

its 600..

I realize even a mild 305 will never need the 750 CFM but that's the flow rate on the q-jet.

http://smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/32

I realize even a mild 305 will never need the 750 CFM but that's the flow rate on the q-jet.

http://smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/32

if you look closely you will see these are not for any stock 305cu engine.
these carb's can be modified however and maybe 900cfm can be had..

I did a search and found that these can be jetted to 1000cfm...

the 305 cu is a problem using a higher cfm...the intake ports are restricted in the design thats why you go with the 350cu..
the 350 cu is a common boat engine..this is where the high cfm carbs are used..
maybe you could put a 650 cfm and get away with it ...could destroy the cat converter ...

Plus the 350 out of Boats have a differant camshaft,a RV cam which has to be changed.Another problem with rebuilding an engine is finding someone that stands behind their work on machine work and does not screw you around.

if you look closely you will see these are not for any stock 305cu engine..

Their electronic stage 1 Q-jet for my stock olds 307ci is also rated at 750 CFM so they claim.

I plan on having them do a rebuild on mine soon.

Their electronic stage 1 Q-jet for my stock olds 307ci is also rated at 750 CFM so they claim.

I plan on having them do a rebuild on mine soon.

the 307 cu olds engine is a better engine...than 305cu. has more torque lower RPM'S. good for a heavy car...like wagon or fully loaded buick lesabre/delta 88...last longer more durable..

The 305 was never a good engine for creating a lot of power, I actually saw one disassembled and was quite surprised at how small the cylinders were in comparison to the other small blocks I had worked on. The heads were kind of a mess too, small valves, weird chambers but GM had to do something to bring down emissions and that was what they came up with.

You can find the specs for the various GM engines online, 307, 327, and 350 engines are fairly common though and you will probably be much happier with one of them instead of the 305, the 400 has its problems I would stay away from them. Stock 4-bolt versions of the 350 exist but if your car is just a daily driver the 2-bolt version will work fine.

Quadrojets, I have no idea what the CFM is on them for various years and for that matter if its been bored out then who knows what it is now? What I do know is that I had one on my 1968 Chevy Impala with 2-1/4 inch dual exhaust and when I stomped on it that carb would launch the car down the street.

quadrajets will flow up to 750 cfm if needed, but unlike a holley 750, it will not over carb a smaller engine with less power.
this is due to the way the venturies are designed. i remember reading that they are a variable venturi design or something. either way, i would keep your e4me carb.
get a 350 from a junk yard for $100 (going rate around here with a 60 day warranty)
you want to find one from a car that is relatively clean and well kept.
signs of abuse are obvious if you are looking for them.
also, get an engine from a car that was hit in the side if possible
rear end damage could have messed up the rear end which would have messed up the driveshaft which would have messed up the trans and most likely the engine as well.
front end damage is not all that bad but you will need a new radiator for sure lol.
honestly, i would get the engine, have a shop look it over, put a mild cam in it, 1.6 rockers if you can afford it, and call it a day.
heads and intake are great, but a lot more $$$.
despite what people say, there are NO stock heads worth swapping onto a motor if you put a big cam in it.
they may be better than whats on there, but paying $200 for a slightly better casting, and paying $800 in porting, then another $50 for headgaskets doesnt make sense when you wont be much far ahead in the end, especially considering that $1500 will get you a set of real performance aftermarket heads that will blow your stock headed motor out of the water.

as for the intake, what would you plan on putting on it?
an air gap manifold is nice and will get you extra torque, but again, its $$$, and i dont think a quadrajet will bolt up (i could be wrong)

There seems to be a lot of misinformation regarding the Q-jet here. GreyGoose is closer to the truth than ANYONE else here.

First. The Q-jet is capable of upwards of 780CFM from the factory.
Second. The carb will ONLY deliver the airflow the engine needs, up to 780CFM.
Third. The air valve on the secondaries is what regulates maximum airflow and if this is not adjusted, people will have problems with this carb. In fact, this seems to be the root of many problems with this carb.

A properly tuned E4ME carb on your car will outperform any other carb for street use and will do so using less fuel.

First. The Q-jet is capable of upwards of 780CFM from the factory.
Second. The carb will ONLY deliver the airflow the engine needs, up to 780CFM.
Third. The air valve on the secondaries is what regulates maximum airflow and if this is not adjusted, people will have problems with this carb. In fact, this seems to be the root of many problems with this carb.

A properly tuned E4ME carb on your car will outperform any other carb for street use and will do so using less fuel.


I was surprised that it is stated by carb rebuilder companies that they can do 1000cfm...

not gonna get any of these carb's from factory !!

on the proper adjustment or even harder increasing the cfm of the carb for the 305cu correctly from the original..who's gonna do that work correctly..maybe where you live this is still a quite common engine /vehicle that the repair shop will have this knowlege.