before I shelled out money for a 350, I want to mod my 305 as much as possible (86 Camaro Z28, 4 barrel holley carb 650cfm). Would adding a carb'd intake manifold, shorty headers, and possibly new heads be all? Suggestions Please.

Also if I just did the intake and headers should the heads be done as well?

 

its all about how far you want to go. heads will help, but you have a lot working against you like compression, cubic inches, exhaust flow, cam timing and size.... I was gonna do the same thing but I decided to just put a punched out 350 in mine

 

Need to figure out what you want to do with the car, Cam, intake and exhaust (long tubes and full cat back) are good for prob 30hp as long as you get parts that are made to work together. Meaning a cam that matches the intake. But the $1500 you will spend min on all that, could just buy a 350 from a junk yard that has that much more stock. lol

 

I took an LG4 years ago that ran high 15s. I put a summit cam maybe 218-220 lift 450-460 some odd duration,good intake with holley doublepumper and headers. It dropped about a second. So yeah you can look to gain maybe 40+ HP. Not really worth it IMO.Few years later my 91 z28 with stock Lb9 was faster with only cat delete and 3 in exhaust.

 

I don't think it's money well spent going into a 305 too deep, but if you use parts that can work on both a 305 and a 350 then when it comes time to do a 350 swap you will be ahead of the game as you will already have some good parts to work with.

I would go with 1996-00 chevy truck L31 350 vortec heads. The vortec heads will drop your compression alittle now (from 9.5 to 9.0) , but they flow great and will make power on the 305 and 350.

Fel pro 1094 head gaskets.

Vortec intake like the edelbrock performer or performer rpm or summit stage I or stage III.

Hedman long tube headers, or hooker shorty headers. 1-5/8" tubes, 3" coll.
Aftermarket Y pipe, etc.

Drive it like that for awhile while you build your suspension up and get a 350 to rebuild.

Don't waste money on a cam swap, pistons, etc for the 305.. All of the above parts will swap over and work well with a 350 later on

 

its just an engine. it does not know its a 305. it will respond to the very same things all engines do. specifically, induction, exhaust, cam and compression.(turbo&intercooler) you can build a 330 HP 305 if you make wise choices ,and it will have decent street manners. it all depends what your goals are. or you can listen to the "freefiddy" crowd and have a gas hogging POS . bigger is not always better, its just bigger.

 

Sorry but I strongly disagree with that.
It know's it can't breath do to it's tiny 3.736" bore
It know's it can't handle a 2.02" valve, because valve will fit the cylinder bore.

Yes you are correct, it's just an engine..

But it will not respond just like any other engine.. It's the small block chevy with asthma.

You wouldn't compare an olympian runner to a man rolling an oxygen tank along with him due to his bad asthma, or emphysema.... They are both people though..

But one can run like the wind and the other one can't breath well enough to walk far much less run..

That's the 350 vs 305

 

hey I don't mind, BUT a 305 has a smaller bore, yes. 3.766 if you go ,030 over.but the valves it has are a good match for it. im not gonna start the ol 305 vs 350 thing again. that horse has been beat to death. but I will say for those building for the street and NOT the track when done right. they give respectable power AND decent mileage. nuff said.

 

Gas hogging POS...350 SBC 350 is far from POS. It will respond and it will perform.

 

So intake manifold and headers would be enough, and leave heads alone? I already got a good price for both (intake/headers). I eventually want to get a 350 w/ vortec heads. I want to keep this motor because I want to put it in another project down the road.

 

So intake manifold and headers would be enough, and leave heads alone? I already got a good price for both (intake/headers). I eventually want to get a 350 w/ vortec heads. I want to keep this motor because I want to put it in another project down the road.

Oh I also forgot about the rear end. Thinking 3.73?

 

Depends on transmission. When I had the original 5.0L H.O in my car it still had the 5 speed. I have the original Australian rear, the 3.71 rear gears made a real difference. helps the engine pick up much faster. Now that I have the 6 speed it has made my 1st gear almost useless since I have to shift too fast. lol

 

U gotta listen to these folks, I continue to drive my SBC 305 daily & will do so till the engine blows. This 305 is so reliable, but it's a dog! 15.5 in 1/4 mile!!!! U get more bang for your buck w/350, but it's your ride/cash. When I need speed, I drive my 96 Z28 & decided to not swap the LT1 into my 84 cuz the 96 is such a badazz car. best wishes

 

yeah you will see a modest gain doing those things, and whats good you can swap it over to a 350. I would do a single plane intake and a 3 inch full exhaust so when you do switch it over your not re doing it. and look at you ignition timing bump that up until it pings then back it off a little then check it with the light to see where your at. and if you want to go deeper check your timing chain and gears if they are super sloppy that will change cam timing and you will never be able to correctly tune your engine

 

I agree, for people on a budget for everything like me, I would rebuild a 350 [if my purpose was horsepower alone]. No, the 350 is far from a POS. I suppose it is a POS if you're only judging it by fuel efficiency.

I may be rebuilding a 305 soon just to retain some fuel economy. I'm not personally trying to drag race or wrap my car around a pole, or fly through the intersection at midnight. My pathfinder got 10MPG, and I don't want to go back to that nonsense.

I've got a very tired 305 that still performs good enough to cruise around, but fuel efficiency is out the window due to wear and tear.

Any 350 guys have gas mileage numbers on theirs? That is literally the ONLY THING that would make a 305 desirable at all, hoping to squeeze gas mileage on cruises. Also depends on transmission, rear end, etc.

To anyone who argues that I'm crazy for caring about fuel efficiency, it's rather a novelty to me. My dad's '70 Challenger has a 318 and a little 2 barrel. Over 200HP and still gets about 18-20MPG on a gentle freeway cruise. Not going to win any drag races, but WAY more fun to drive than the wife's Focus For adventure, my room mate has a 700+ horsepower Cobra... I guess when you want to play, you gotta play.

Cheap rebuild kit on the 350 is actually about $40-60 cheaper than the 305 kit.

 

My heavily modified Procharged 350 gets over 20 mPG on the highway. I run a DFI system with it and with the Wide band o2 can fuel it for economy very easily. If I want to make power its just a key stroke away.

My point is, even 350's can be fuel efficient, comes down to how you drive and how its configured. You really just need to factor in what you plan to do with the car. Do mild mods to the car like everyone says, stuff that could move to the 350. Just dont be upset trying to race a modern day import and get upset when it smokes you. lol

 

Wow. That's impressive! I had no idea you could do that. I suppose the difference between economy & performance is a/f ratio and timing?

I wonder if it's possible to get such fuel efficiency on the 350 without that glorious fuel injection management system. Hammer it down for power, drive it nice for fuel efficiency. You may have just sold me on my 350 megasquirt swap

 

With fuel injection, you can get over 20mpg with a 350. My carbed 355 hits 19mpg on the highway if i'm going downhill. 18-18.5mpg on the highway the rest of the time. In town..I don't even bother to count.

My 305 would get 23-24 on the highway.

For the 305, if you *want*, you can build a 300hp mouse motor out of it, but it's going to be more expensive than simply swapping in a 300hp 350. Dollar for Dollar, the 350 is the cheaper/better option unless your really gung-ho to keep the 305.

 

LOL, Well I just saw that the new pro key version of the DFI system has the ability to run dual fuel maps. You can set it to a TPS threshold, anything above will set it to a power map, below for economy.

I have a lot of experience with the MS2 system, but mostly on Turbo VR6 VW's. The DFI system is more refined to the TPI system on my car ( comes with everything to just connect and go, even built in maps to get things fired right up. ), and was a no brainier for me. But I know its hard to look away from the price tag of the MS system.

 

my 350 is not near any stock config. and I get 14 mpg driving how I like to drive not fast a lot but I like to use my WOT at least once twice a day

 

You do not want a single plane intake on most street/strip small blocks. I was running 11.40's @ 118 and still using a dual plane.

No times yet on the new combo but upgraded heads, cam, rear gear, carb, ign. and still running a dual plane. It should be a 10.60's car when I get it back to the track.

If your under 383 cid, 500 HP, 6800 rpm peak HP point stay with a good dual plane intake..

I'm running an edelbrock RPM, that I modded. Port matched the runners to my gaskets, milled the divider wall down 1" deep x 2" long and run a 1" open spacer.

 

I know I'm late to this thread but this article is a good read and is something to consider.
http://www.superchevy.com/how-to/eng...-add-168-rwhp/

I have DD my 305 and have gotten good gas mileage 18-20 mpg but I don't go looking for races in my 305 either. They can be fun and still pick on most cars.(sorta)

 

The 350 will get the same or better fuel mileage than a 305 if done right. It's all about engine volumetric efficiency, gearing and engine power band set up for the range in which you drive.

As I posted above my old combo was a carb'ed (600 cfm vac. sec) 10.18:1 355, that ran 11.40's @ 118. th-400 3 speed auto, 2800 stall converter, 3.42 rear gear.

I got 15.4 mpg avg. fuel mileage. Just think If I had an over drive trans. If I had an over drive trans it would be in the 18-20 mpg range.

Now I can't say the same thing though. With a much 'wilder' build my fuel mileage is only 7 mpg but thats with a 249/252@.050" cam, 750 double pumper, 3500 stall converter, ford 9" with 3.89 gears.

I just built a V8 S10. Milder 355. 10.25:1, vortec heads, 218/230@.050" cam, 600 cfm carb, th-350 (cause thats what I had sitting around), 2800 stall, 3.42 gear. I get 14 to 14.5 mpg but I'm still breaking in the engine and have not fully dailed it in yet. Only have about 1,000 miles on it.

 

Also any suggestions on where to get a 373 gear rear end? Do you have to replace the whole rear end? or can you just replace the gears?

 

Most backyarder's can't do a gear swap. It's not as simple as just throwing parts in and bolting them up. You have to set preload, gear pattern, clearances, need some special tools and the skill to know what your looking for.

You can try to find a rear with 3.73 gears already in it and swap whole rear axle (all 1982-92 camaro/firebird rears will be a direct bolt in... Also the 1993-02 F body rear will fit but they are alittle wider and requires you to run 4th gen rear wheels)

Or you can take it to a chassis/suspension/gear shop and have 3.73 put in yours. Parts will run about $400 and labor around $500-600

 

I totally agree with the gear ratio swap. ( and adding a L.S.D./Posi unit)

I believe it should be done before moding the internals of a 5.0 engine or putting in a 350/etc.

But you must ask yourself what are your power/torque goals going to be and what is the car going to be used for.

There are basically two options IMO to consider.
For a primarily street driven car using street tires would be a total rebuild of the 10 bolt with the best parts you can buy = https://www.thirdgen.org/forums/tran...de-photos.html
Or
For a car that is going to see 1/4 mile track use with sticky tires would be a pre fabbed 9" or 12 Bolt specifically for our cars.

Either way, with the gear swap from let’s say 2.73 highway gears to a 3.42 or 3.73 with a good L.S.D./Posi. unit will change the way the car performs "drastically". Just the change to the rear end will "magnify" the fun factor of driving the car.
That's with a good sound engine and transmission.

Those options are not inexpensive, but having the proper rear for your build is important because now it will be able to handle what you put into the rest of the car. Putting power to the pavement with two tires........

 

Ok so for now this is what Im going to upgrade:

Dynomax Super Exhaust System
Flowtech Headers
Flowtech Catalytic Converter Y-Pipe
Rebuild Rear End & swap for 373 gears
New front end suspension, replace shocks & springs all around

(Heads?)

Also have a Holley 4 Barrel Carb 650cfm/ running a liitle rich. Maybe go with edelbrock 600cfm


Not all at once, few things here and there, this is my daily driver for now and just want it to be fun to drive.

Love 80's muscle cars, thanks for all suggestions.

 

Bang for buck, hotcam plus vortecs.... It will run fun

 

The difference between a 350 and a 305 on fuel mileage at the same power level is going to be..... negligible at best. If you care about fuel mileage that much, get a 5.3.

To do a gear swap you probably need at least a 20 ton press, a regular torque wrench, a solid pinion spacer (to eliminate the hassle of the crush sleeve), and a dial gauge indicator with magnetic base.

It's really not THAT hard, the biggest investment is the press, and you may end up using that quite a bit. You can probably get away with a smaller one if you have no desire to press bearings off axles.

 

Add weld in sub frame connectors to the list. They should be the very 1st mod to any F body really, be it gen 1, 2, 3, or 4th.

I would also recommend spending the little extra and going with hooker or hedman headers. Flowtechs are not that great.

I got a set of hooker shorties that I bought back 16 years ago for a '84 camaro. I used them on 3 diff cars, now my dad has them on his '82 firebird.
Got a set of hedman long tubes that was bought 9/10 years ago and have used them on 2 diff cars.

The only set of flowtechs I bought was for a '73 c10 truck and they didn't even last a year. The welds cracked around the collector to pri. tubes, and got a leak from 2 of the pri tubes to flange joints.

 

my take is to buy and build with the 350 in mind , find a 9 bolt with a 327 ratio our 345 ratio from a stick , 1 5/8 long tube headers custom y pipe to cat back exhaust . buy an intake for a vortec 350 750 vac secondary . new shock and struts fix leaks if any on 305 and save up for the swap . you will also need a trans at some point don't buy a tci
street fighter it was the worst money I have spent

 

Sorry if this is not pertaining to the title of this thread but since its been mentioned and is important to any build I would like to add this ....

So what L.S.D/Posi do the stock differentials have in them?

A good thing to know when considering a used differential.

The subject of gear ratio changes most of the time does not seem to mention what L.S.D. they will be getting with the used rear.

Or "I want a 3.42/3.73 ratio change also with no mention of a L.S.D.

Putting two wheels to the ground with a "strong" L.S.D. is IMO a must have and installing one at gear swap time should IMO be a “very” high priority.

That's it.

 

when I tried to keep my 7.5 10bolt together I got an auburn unit Richmond gears moser axles . without fail every 6 months i would split the pinion . i thought maybe i was setting up the gears wrong sent it to a place that all they did was rears .it happened again . after 5 tries i gave up . i went to the junk yard a found a 8.5 from a
second gen that's whats in there now . my gta has a 9 bolt 327 gears , i got from the salvage yard for 350.00 . when i was looking i asked to go to the cars so i can get milage if possible see if its been in the movie joe dirt see if they will raise it up so i can
pull the cover and inspect it check the cones gears. i have beat the hell out of the 9 bolt and did not have a problem.

 

the 9 bolt is more expensive for parts but i feal its good for up to 350 hp
the ten bolt i tossed in the junk yard with all of the stuff in it

 

if you do a gear swap from a 2 series gear to 3 series gear you have to change the diff

 

7.5 10 bolt rears have clutch disc spring setup

 

Just so everyone knows what we are talking about when we mention the difference between a 10 Bolt and a 9" .Not the 9 Bolt.
I'm not even sure my little 5.0 could handle the rotating mass of the 9".

 

I agree If you don't have a 305 that's built with some sort of power adder I would not
run a ford nine inch . that's why the Australian 9 bolt would be a good choice if on a budget. most people purchase a 9 inch ford then ask why there times slowed down .
they don't have enough motor , plus unless you drag race often the benefits of a 9 inch
are not being used ,most bracket racers never swap gears out at the track.

 

when I said build for the 350 I forgot to say think of what power level you are shooting for. then do the research and choose the parts the meet your goal . I built a 305 for my
iroc so I can get it back on the road . im going over the 357 and th400 . at best the 305 might put out 340hp the th400 will eat a lot of power so im putting my 700r4 in

 

im restoring my car from when I was in school I never got rid of it .when I got married
my wife wanted gone. I told her I had before you I have it after , there both still with me

 

never get in between a man and his third gen you will fail!!!

 

the nice thing about the 9 bolt is its like a ford 9 inch the axles are held in with bearing plates our c lip eliminators to most

 

The 9 Bolt seems to be superior to the 10 Bolt I had built over 5 years ago. I must say though it has seen easily over 100 launches so its working for me just fine.

I just don't like the fact the 9 Bolt Cone cannot be replaced when it wears out.

Or can it ?

 

It can.

New cones can be ordered. But they require the case to be slightly modified, or the new cone to be slightly modified to fit the case. it's not a direct bolt in, but the modifications aren't a huge deal. Something you can do with a grinder by hand if you're REALLY good with it, but not really the best idea...

The problem is that the shims needed to shim the new cones arent exactly available at the parts store, and I've heard REALLY mixed things about how long fresh cones last in these thigns, probably due to the problem with how to shim them and how much preload they are supposed to have.

 

So for now this is what I;ve decided to now:

New carb(600cfm,electric choke) and intake- Edelbrock

New Headers & Y-pipe- Hedman

New front end, shocks and springs all around

rear end rebuilt and adding 3:73 gears

New valve covers & gaskets

New Pulley system

 

Don't forget you will need to get new drive/driven gears for your transmission with the rear-gear swap.

Is your current Holley Carb not an electric choke?

I would also go with Dyno-Don headers if you aren't keeping the emissions. better build, last longer, etc.

 

It is a electric choke but i got a 78 nova im restoring and going to get the holley rebuilt/cleaned out etc, and going to put in on there.

What is the cost for new drive/driven gears? and where to find? also I got a quote from a gear shop to rebuild the rear end and put the new gears in for around 725$, does that sound right?

 

That's ballpark for a rear-end rebuild. I paid $800 for my last one. I just don't have the tools or know-how to do it myself.

For the drive/driven gears, any reputable transmission shop should be able to hook you up. If not, there are some online resources you can turn to. Google search should get you where you need to be.

As for which ones you need, there is a huge thread here on the site somewhere that has a nice list (I've seen it but it's been a few years) of the drive/driven gears needed when compared to tire-size and rear-end gearing you have.

 

This is my first time getting my rear end rebuilt so bear with me. Should I get the transmission shop to put the drive gears in or purchase them separate and have the gear shop put them in during rebuild?

 

The drive/driven gears are in the transmission. I've heard varying accounts of being able to replace them while the transmission is in the car so from what I understand, it's doable. Were it me, I'd have it all done at once by the shop, if they're willing to do it.