Jared Moore

So, I'm planning on doing an engine swap in the future to replace my 305 in my 92 firebird right now. Which is better over all, 350 or 383? Thanks

fasteddi

iTrader: (2)

dmccain

iTrader: (2)

More cubes more power. If you plan on racing do the 383. Be forewarned though. It will be a torque monster and shred tires and stock rear-ends.

Orr89RocZ

iTrader: (20)

Cubes is always good in na application. If you are buying a crank might as well go 3.75". Now if you are on a budget and need to run stock crank that is fine. Can make a very stout 355

-=Z28=-

iTrader: (3)

you can get a scat9000 for cheap(3.75). def want to balance your set-up.

Tibo

iTrader: (15)

Depends on your skillset and pocket book. Personally I would build an all forged 35X engine and do a turbo. I seem to come across lots of used forged 350 cranks and rods and roller block sbc are not expensive or hard to find anymore. If I couldn't do that I would go with a 383 stroker. I'm currently enjoying my second 383. That prementioned Scat 9000 crank, forged pistons and rods with a 230-240 cam is a great street engine, small lope and a good powerband. Depending on the heads and and some other bolt on parts it can easily produce and handle 350 rwhp up to just north of 400 with those parts.

TOM305T/A

just wondering, if u have 350 bored .30 over. is that a 355? how much addl hp do u get from being bored .30 over?

Jorlain

iTrader: (4)

The guidelines I stick to for building engines goes something like:

1) If you have to replace\turn the crank, add stroke.
2) If you're throwing boost\N2O at it, build for durability.
3) If you have to mess with the fuel system on a carburetored car, switch to fuel injection.
4) If it's an auto, replace the converter after considering your rear gear ratio, transmision, tires, and desired power band.
5) Remember, the engine is only one piece of the car.

There's more to go through obviously, but it's usually where I start when friends want a 10 second car to show them that there's a lot of things to consider.

sofakingdom

iTrader: (1)

Cubes are good. But there's more to it than that.

Jorlain's list makes good sense. Use as much of that as applies to your situation.

I would NOT NOT NOT NOT NOT NOT NOT spend money on a 70s 350 block, PERIOD. Not on a rebuild, not a crank kit, not a can swap, NOT NOT NOT NOT NOT NOT NOT NOT.

Used to be, I'd advise people to look for a 400 block. Unfortunately now, in 2017, those are becoming far and few between. Time was, you'd find some old broken-down van or station wagon or some turd like that in the buzzard nest, and there'd be ... a 400, that nobody else noticed. Those days are pretty much OVER.

Today, a roller-cam 350 block is the foundation of choice for a 1st gen SBC. And blocks today, with modern FI, don't have what we all used to call "Powerglide wear", which I now realize, wasn't the PG AT ALL. It was the POS 2G carb washing the oil off the rings during cold starts. You just don't see blocks that the wear at the top of the cyls is so bad they won't even go .060", anymore.

First question I'd ask though is, why "350 or 383"? Why not 5.3/5.7/6.0/6.2? Those engines will UTTERLY SMOKE the old small block. As good as it was for as long as it was good, ... times have changed. If you are starting out from DEAD NOTHING, widen your options.

NoEmissions84TA

iTrader: (1)

Don't forget about your exhaust system. More cubic inches and increased HP need to breathe. You can't create a 500 HP engine and expect to exhaust through a drinking straw.

Jorlain

iTrader: (4)

Sofa has hit the nail on the head. The LS is the way of the future, as much as some dislike it. The LS platform has a HUGE aftermarket, not unlike the SBC. The bottom ends on these are about as stout as they come (without spending thousands on a rotating assembly) and a swap to LS6 (243) heads if necessary will get you to supporting 450hp, give or take.

There are some caveats, however.

Since our cars never came with LS motors, that means we have to do some fabrication or pay someone for their fabrication. Swap parts can get expensive real quick. If you're starting from scratch, it'll cost you about the same either way as you'll end up putting more money into the SBC than the LS, but you'll use that money towards swap parts instead. The scales might tip towards the LS route being more expensive if you're not patient and\or deal hunting. There's also the concern about your ECU tune. Unless you're proficient in tuning, you'll have to pay someone to do that for you. The best tunes come from fine tuning on a dyno, so you need to pay for dyno time also. If you're just throwing in a stock LS without any changes, there's no need to tune. Most people do a cam swap at least, though, even if it's just a used LS1\LS6\Hot Cam.

On a side note, you may want to find yourself a spare rear axle to keep around in case of trouble. Our tiny ring gears don't last long with any sort of power and traction. Do yourself a favor and start saving for an aftermarket rear for when the inevitable happens.

-Mike

89Warbird

If you are going to replace the engine then get the 383. Mine is a 6 inch rod 389, 383 bored .060 over not .030. Truly it's 388.4 CID but, close enough to the historic Pontiac 389, so, I have a 389! It doesn't cost anymore than the 350 so you might as well do it, remember the old racers adage, "There is no replacement for DISPLACEMENT!

Jorlain

iTrader: (4)

I somewhat disagree. A 383 will cost you more if you would otherwise keep the stock rotating assembly. You also need heads that can take advantage of the larger displacement\stroke. If you're not getting any more air\fuel into the engine all you're doing is wasting money.

Also, as far as "there is no replacement for displacement", that's only true within a category and with supporting modifications. We have other options now.

89Warbird

Nothing you would ever notice, 5 HP/TQ if your engine is 1 HP - 1 CID.

89Warbird

If you have a 305 donate it to a boat owner for an anchor and start over with a 4 bolt main block and build a 383. You are going to dump those 305 heads as well, they are too small and not worth the cost to port and put in oversize valves. You are getting an entire new engine, you don't want to use anything off the old engine except maybe the upper plenum of the TPI unit and that's it.

Also, yes plenty of power adders around. However, you can only wind an engine so tight, then you up the displacement for more power. Compare a 305 CID pumped up with dual turbo's intercoolers and Nitrous to is MAXIMUM potential. Can it make more HP/TQ than a 455 built with the same mods to it's MAXIMUM potential, no! So, "There is NO replacement for displacement!

Jorlain

iTrader: (4)

Again, I feel that is only true within a category. A 350 has more potential than a 305, and a 383 has more potential than a 350. However, I'd say that a 5.3 is far superior to a 5.7 even though the 5.7 is larger.

Now, all of that being said, if you're buying one already built for you, then yeah, do a 383. It makes sense. But if you're planning on grabbing a 350 from the junk yard, it doesn't make a lot of sense to go with a 383 unless you like lightening your pocket book. You're looking at 1500 for the rotating assembly, plus another $200 to balance it. Then you have to machine the block. There's another $800. Bare heads to support it are another $1000 (unless you got Vortecs with the junkyard engine, then you just need to pay for a valve job, cut down the guides, magnaflux, etc. ~$300 or so. Lose a lot of power this way though).

So, pretending that we paid $300 for a Vortec truck engine\heads that doesn't need to be bored, we're looking at $2600 for the short block plus bare heads.

Taking that same engine we got from the junk yard, we bring it into the machine shop to get it hot tanked, cam bearings\freeze plugs, polish the crank, rods checked, heads checked, and a valve job\guides cut for $500. If you decide to change pistons, figure another $250 for the pistons and to have them pressed on.

This comes to about $1100 give or take, or about $1500 cheaper than the 383. Assuming we have to pay for the valve train, cam, gaskets, bearings, etc, for both engines we'll just leave it here.

So what do you lose? Well, with the aftermarket heads on a decent street combo 383 will probably get you 450/450 HP and torque respectively. The Vortec headed 383 will probably end up around the 400-420 mark. The Vortec headed 350 with flat tops will be at the 350-380 mark.

*This is all assuming you're not using a stock TPI and you're using all of your accessories.

And then Mr. LS rolls up in his L33 and smokes us all.

-=Z28=-

iTrader: (3)

But then as stated above, its way more that just the engine. drive line, rear, tran, etc. Best advice I've read in this thread is build to your budget. I recently built a 383, do a search, and it will show you all of what is involved. plus a bunch of cash. I have been thinking of doing a LM7 or of the like, 1) I need to learn about that field, 2) They are light years ahead of 1st gen sbc. I will always love old school blocks but its time to get in the new.

fasteddi

iTrader: (2)

I think it just depends on what you have access to. Me personally i had access to a great 385 for a under 3k and it was from pan to carb. So i went with that when doing a V8 swap. Of course since ive added alot of things to it in hope of making it a 10 sec car which i have no doubt it will be but a old 355 383 is still a very common motor. I ran some 11.60s with my car ever week at the track and spent less then 3k on the whole motor swap including the engine.

So if you intent is only to run 11s or so on all motor then I say that a old school 4 bolt 350 block(383-388) or even a 400 sbc block is a perfect step, its not very hard at all. So dang easy to mod and work on. Just my 2 cents.

Jorlain

iTrader: (4)

Overcomplicating things is in my nature. Someone thwap me.

What they said is pretty much what I meant. Build the best base that you can afford and that is within your reach. Building something that takes you 2 years to scrounge up the cash for and eventually ditch and\or get bored of isn't nearly as "good" as throwing something you can afford in and driving the hell out of it for 2 years.

Arctic White 91 RS

350 or 383? Neither. The 383 is better than the 350. However for what a motor build costs I'd skip both of them.

If your going to spend the coin to build a SBC get a Dart SHP Block with 4.125 bore. It's easy to build a 4.125 bore x 3.75 ( or better) stroke motor that works out to 400 or more CID. The Dart block also has many improvements over a production block.

sofakingdom

iTrader: (1)

While that's a great idea, and arguably a highly sensible one for a "serious" kind of Gen 1 SBC engine builder these days, I kinda doubt it's "The Right Answer" to a guy that doesn't know whether a 350 or a 383 is better.

For a guy like that, a motor that (a) he can get done in a time horizon that doesn't rival retirement, (b) doesn't cost as much as 2 years rent, (c) doesn't require detailed knowledge, planning, support parts, and other stuff only acquired with even more $$$$ or LOTS of experience, and (d) runs as good as or better than something that somebody else spent more $$$ on, is probably a good measure of success. It's not always about making "The Most Power" or whatever; there's other measures of success for other kinds of people.

That's what makes a 5.3/4L60E pullout SO DAMN POPULAR. It's cheeeeeep, reliable, effective, cheeeeeeeep to operate over the long term, relatively eeeeeezy, the knowledge is WIDELY available, and can be done in acoupla weekends of actual swappage.

Arctic White 91 RS

sofakingdom, I tend to agree that an LSx/4L60e swap of some sort is the ideal way to go for most of these swaps.

Hopefully the OP will read and learn more to get a better idea of what will suit him best.

​​

skinny z

While on the topic of the LS swap, you have to consider the cost of the swap itself compared to what's involved in just going up in C.I.D.
Case in point,(and this may be relevant to OP's original question) my 355 is worn out. While the crank and rods are sound enough to reuse, and of significant value to reuse, I'm faced with the idea of just swapping out the shortblock and going with the top end I have now. As was pointed out, if the current reciprocating system needs attention (turn or polish the crank, new pistons + re-balance?), then leave it and add the stroke on a new crank (plus rods, pistons). Interestingly, I've found an all forged shortblock (with made in USA parts) for less than 4k USD. That's a 4k outlay seeing as I have the rest of the parts. Bolt in and go. (Might need pushrods).
Now if I were to go LS, even though I have a 5.3 (LM7), I'd need more than 4k to make it fit. Engine mounts, headers, accessory drive, oil pan, intake and TB, (ECM?), flexplate (to work with my existing Gen 1 TH700 or add a trans swap to the list), transmission mount, etc. Not including what's involved to bring it all together tuning-wise.
So it's all about the particular circumstance, including parts available and budget.

NoEmissions84TA

iTrader: (1)

Abubaca

iTrader: (3)

Frankly.....we need more information. I understand what you're asking, but it's just not that simple. It's just not. Budget, goals, skills, etc. etc. Dad used to say don't put anything on your car if you can't explain WHY you're doing it. Meaning do your research. Take our advice, absorb it, research it and come to your own conclusions. I've made countless decisions on how to build my car that definitely are not the "norm" or perhaps the "right" choice, but they were right for me. In my opinion, with the amount of time and money that this hobby eats up.....knowing for yourself why you've made certain decisions is the only way to go.

Jorlain

iTrader: (4)

In any situation conceivable by my brain, a car that runs and drives (even slower than you'd like) is better than a car that gets left in your garage to rot for 10 years because you get bored or run out of money.

Build what you can afford and get back in the car so you can enjoy it.

But being that Jared hasn't logged in since December, I'm guessing this is all a moot point.

skinny z

Such are the forums. I've gone back to a few I've posted in and asked for updates and on a couple of occasions been surprised with progress. Perhaps our OP will drop in.

Tibo

iTrader: (15)

True, but the clencher for me is now how cheeeeeap you can buy a pullout LS engine that makes at least 300hp to begin with. Stick a cam in it and change the intake and you have 400hp. To do that with a SBC you need lots of expensive aftermarket parts. If my current 383 blows I'll be crying in my beer for weeks about how many parts broke and how expensive they were and the machine shop bill and how long it's going to take them. This compared with the LS guy who can be up and running in one weekend.

fasteddi

iTrader: (2)

I disagree and say it just all depends on what you have or find. Also what you know how to do.

I think i said this earlier in this thread but i got a 385 sbc for 2500 bucks. Which you can find pan to carb sbcs all day long on classifieds and racing forum, or from word of mouth.

Mine had a eagle rotating assembly, comp cam xe268 cam, dart 200cc iron heads, performer rpm intake, proform elec water pump, 11.1:1 compression, msd pro billet dizzy, holley 750 dp carb, comp cam gold 1.6 rockers... the list goes on. So for 2500 bucks I swapped it into my former Turbo V6 camaro in litterly about 12 hrs of work. I added in the regulator to step down from high pressure to low with a return style regulator, and moved my motor mounts for the V8. It was so easy to do.

Granted some dont like carbed cars, but the point remains that ya ls engines are nice and very common, but there is nothing wrong with a solid 355 or 383, 406..exc. Any sbc in my mind is quite easy to make it fast weather its a ls style or gen 1 sbc.

By the way that 2500 dollar turn key engine i got ran constant 11.60s @115mph at the track shifting at 5400 rpm.... yea it wasent built to rev at all. But it was a mild build and was fun to drive on the streets while still laying down mid 11s on drag radials at the track.

I just recently did some mods to the old sbc because I want to run some 10 second passes but if you only want a 12 or 11 second car, a ls or even a low cost gen 1 sbc will get the job done easy. Its pretty easy to make any sbc in a f body fast if you have the correct supporting mods....converter, trans, rear, suspention...exc.