I just showed you a real world comparison of very similarly built engines in similar cars. Show me a better one? They run very much the same up to 100mph. This is not scientific. The 305 hangs with the 350...yes mostly because of the rear gear. Show me a better comparison? At this hp level 325-350 Not a big difference like many 305 haters seem to push. Would be hard to get 450 hp out of a 305 no doubt and a 350 would make that easier.

 

You're right, it's not scientific. A "real world" comparison would be dyno results...

 

Wow your making this difficult. More real world than actually driving the cars against each other? Yes the 350 prob makes 20-40 more hp..and 50 lbs ft of torque more. The whole point of this post was to show how using vortec 305 heads on a 305 with similar compression cam and such can make a decent running street engine. Nobody is saying its better than 350! But surprisingly competitive in this case. I cant wait to run the 305 car at the track next year. Surprisingly easy and cheap build for a 305. I had stock 416 heads on the 305 previously. Could not keep up at all with the 350. Now go away 305 hater!

 

I was kind of w/TL....now I see you're more so going for the subjective "how it feels" points.

Yeah? The 305 pulls the 350 by "a bit" over 90? But the 350 pulled the 305 by a full car length going up a hill? That doesn't "jive". It's just too uncontrolled to make any real claims or determine anything concrete. My takeaway is that you got two sort of similar combos but not the same, that provide about the same SOTP experience? Sort of? And that's cool. But check this out.....
THAT is objective. with a 104 trap, you've got about a 300-320ish hp car there. Pretty good. What's the 305 car? You don't know...we don't know. SOTP=WAG.

 

Runs even with black 350 car? Neither car pulls more than a length. How's that for knowing? Repeatable many times over. Lots of fun too I might say! I was surprised as the 350 car feels stronger stabbing the throttle. But the 305's power comes on pretty good after 4000 rpm. Ill post the results when i get a chance to run the car at the track. I'm sure the 3.73's are helping a bunch with the smaller engine. maybe ill swap axles and find out. How's that for scientific? lol

 

I'd just take the 305 to the track and get a trap speed. Assuming the cars both weigh the same....there's your objective comparison.

I'm a 305 hater....and I've had 3 of 'em. But MY comparison is:
Two box stock Chev Silverado, x cab, short bed, 4x4 trucks, both 5 speeds. One was a '96 350. The other, which I have now is a '98 305. Same-same, both stock, Vortec/5 speed same truck. One of my "dyno's" is a canyone I climb every day; Parley's canyon which gains ~2500' elevation over 13 miles from SLC to Park City. Climbing Parley's....
350 would go any speed I want (up to about 80?) in 5th gear. No prob
305 won't make it in 5th gear. It'll go ~75 in 4th.

Towing my boat up Parley's...
350 would go any speed I want (up to ~80) in 3rd gear.
305 will only go about 55-58 in 3rd. Using second gear, it will make it allllllmost to the rev limiter (but not quite) at 62 mph. So it's tapped out at 62/5500 RPM

Both stock Vortec engines in the same vehicle, same configuration, same gear, same trans....same-same. The 305 uses more gas in all driving conditions that I encounter. I wouldn't buy a 305 version of this truck again. I'd buy another 350/5speed in a second.

 

I've always preferred a 350 also. Its a no brainer if you don't have a good engine already. I decided to experiment with this 305 only because its a numbers matching l69 block for the car and ran well with 100,000 miles. I did all the mods such as cam, intake and 1 5/8 headers, with a flowmaster merge into a madrel bent 3" pipe back to a Magnaflow 3" Camaro muffler. Identical setup to 350 car. they both run Qjets and chinese performer copy intake manifold. Nothing special. With the stock 416 heads it ran better but was not what i hoped for. I decided to try vortec 059 heads after reading many of Fast355 posts over the years. Found rebuilt pair for $450 online. They fit the small bore 305 well and flow better than old camel hump heads from what i have read. My butt meter says a 50 hp improvement over the stock 416 heads and now the car runs as fast as a almost identical car with a mild 350 build. This 305 is a mild build also. Idles at 750 rpm pretty smooth once warmed up. Summit el cheapo 1103 cam and lifter kit. I am surprised to say the least. Now put this motor in a heavy 4x4 truck and the 350 would perform better im sure.

 

I think somebody said WWWWWAAAAAAAAAAAYYYYYYYYYYYYYYY earlier on in this thread:

Anything you can do to a 305, you can do just as easily to a 350. Only difference is, you START OUT WITH about 15% more, and you get about 15% more out of everything you do. FOR THE SAME $$$$. EVERYTHING. Buy a cam, you start out with 15% more, spend the same, and get 15% more on top of that. How is this hard to understand?

Why would you limit yourself to 15% LESS for your dollar? COMPOUNDED?

Let's apply a technique I learned (sort of) from one of the most intellectually gifted humans to ever live. I'm much too stupid to even observe such heights of genius, let alone aspire to ever achieving even a tiny fraction of what he did. But however all that may be, he called his technique the "thought experiment". It allowed someone willing to escape the bounds of their own preconceptions and prejudices, to fill in the blanks about what would have to happen if certain other things happened. It was particularly useful for situations that couldn't be duplicated on Earth even if they might exist somewhere else in the universe, but can be just as worthwhile in situations that are hard to do an A <—> B comparison with. So, let's do a quick one.

You go to the grocery store looking for steak. They have "levels" of the steak experience, like rib-eye, porterhouse, T-bone, round, chuck. Each one is a 15% increment in price above the next lower one. Furthermore, each packaged one weighs 15% more than the next lower tier. OK: the store offers a 0.87 lb porterhouse. You walk into the store and think, OK, looks good, I'll go for that. BUTT, for THE SAME PRICE, you can get 1 lb of rib-eye. 15% more food, and 15% better. Now the $64000 question: WHY WOULD YOU EVER BUY THE LESSER CUT OF MEAT? There's no real difference when it comes to motor displacements in the SBC family; a cam costs the same no matter what displacement, boring/honing costs the same, crank work costs the same, valve jobs cost the same, pistons cost the same, spark plugs, oil, coolant, ... all cost the same; WHY WOULD YOU DO ALL THAT TO A LESSER MOTOR when you can do all the same things to a GREATER one and get COMPOUNDED better results?

THAT'S what's wrong with the 305. Not that it's "bad"; just, there's BETTER choices, and therefore BETTER ways to spend your money. Spend EXACTLY THE SAME, get COMPOUNDED BETTER results. It boggles the mind to contemplate how stupid, stubborn, and pig-headed someone would have to be to ignore and even ARGUE AGAINST such a simple and obvious FACT. Yes I'm talking to those who have attempted to defend the 305 in this thread. YOU are the stupid, stubborn, and pig-headed ones.

The 305 is a perfectly OK motor, IN A VACUUM. If there were no other SBCs to compare it to, it would be ... divine, almost. BUTT: there IS something else. That "something else" is BETTER IN EVERY WAY, and ther initial cost of buying it (the core) is utterly NEGLIGIBLE in the big picture. Most especially, it's negligible if the "goal" is fixed: so many HP, a particular ET, or whatever. Whatever the goal is, it's EASIER with the alternative to the 305, than it is with the 305.

There are no "alternative facts", only alternative logical fallacies that the deliberately self-blinded might choose to allow themselves to subvert the cognitive dissonance that comes from willful idiocracy.

 

Oh also ran a 300 mile round trip down to Walla Walla to pick up some parts. I'm seeing 22mpg at least on this trip with the 305. My 350 car gets 20. lol same carb, intake and headers, and 323.vs 373. Just saying...Im not a 305 fanboy...But performance in these two cars is way closer than expected. 13 second 305 with cheap heads, cam and intake? I think its a reality the vortec heads allow. In fact im saying i have a 13 second car for cheaper than if i would have built a mild 350! Now if i wanted to run 12's or faster, might be a different story. 350 all the way.

 

That's a lot of rationalizing for the 305 going on there. It's working for you though.
FYI, that 350/speed truck I mentioned above? That would get 22 mpg on a higway/road trip. A truck. My '92 'Vette (which obviously has a 350) will do 30+ on a highway trip.





So, 22 out of a 305?......

One of my Trans Am's (back in the day) started with a 305. It consistently returned 24 mpg, hwy for me. I put in a 350 (LO5). It consistently got 24-25 highway. Maybe the increased displacement was offset by the swirl port heads? Nope. Later, I put in a 400, medium cam, ported intake, bored TB's, and other mods.....still got 24 hwy and on one trip from Utah to LA, it got 25.

So? I don't know that a 305 getting 22mpg is a "selling" feature for the 305.

 

Double post

 

Sounds like you need to fix what is wrong with your 305 Vortec. Low fuel pressure or a plugged cat maybe. I have driven and owned half a dozen of each. The 305 and 350 have close to the same power even with 5-6k on the back. In the 3,000-5,000 rpm range the 305 and 350 make very similar power. The 350 falls on its face way earlier then the 305. In fact I have dropped the shift points from 5,000 to 4,600 on several 350s just to make them not feel like they are dying out. On the 305s I usually raise the shift points a smidge because they are still pulling.

The 305 in my 99 Tahoe with headers, baby cam and a volant CAI would do bad things to a stock 350 vortec and showed tailights to a couple of 5.3s. 305 got 22-23 mpg highway in a 5,000+ lbs Tahoe on 32" tall 20s with 3.42s. I pulled my 6,000 lbs travel trailer with the 305 a few times and it handled it like a champ. No problem running 70 mph in 3rd gear at about 2,600 rpm. Also pulled the same trailer with my Express van with the 350 and shorter tires. The van has shorter 30.5" tires and 3.73 gears. ~3,000 rpm at 70 mph. Tahoe had a 60E and the van an 85E. Power wise the Tahoe would get the trailer rolling noticeably easier. The van now has a 383 and the Tahoe an 8.1L and 80E. Van was about 700 lbs heavier then the Tahoe but had a small cam and headers as well and 45 cubes more.

Its not a little aerodynamic trailer I am pulling either. Its 26' long, 10' tall off the road and 8' wide.



The 350 in the van was no slouch either. Not towing anything it would run whatever I wanted to run. Could set the cruise at the GMs limit of 98 and the cruise would hold it all day long. Cruise can only open the throttle 3/4 open. The 305 in the Tahoe had no problem going faster then you would want to drive the brick.

 

Nobody asked for your opinion to be frank. Frankly I do not care. I have built several good running 305s. Good 350 blocks are becoming harder to find. I have had several 305 blocks given to me that only needed to be honed, new rings and new bearings. I have slapped together 300+ hp 305s cheaper then I could have bought a core 350 for. In every vehicle I have run them in a 305 gets 2-3 mpg better then a 350 in real world driving.

As I have also said before...Why stop at a 350? When a 383 and 396 can be built from a 350 block for nearly the same money. Then why build a 350 when an aftermarket 400 block is not much more. Then again why stop at 400 when the rotating assembly for a 415 or 427 barely adds anything to that Dart SHP block. I built a factory 880 block 383 and would not have spent much more building a SHP block 427. Talking $800-900 more at the time. 383 runs great but a 427 would have been a different beast all together.

Then again if cubes are the answer, why not a big block 454? Stroke it to a 496. Or maybe a 502? 632? Why build a 350 when you can put 454 cubes in a small block?

 

They're not the same power and we know that because of the rating given to them by GM. This is REALLY basic stuff that doesn't need to be debated.

There is nothing mechanically wrong with the 305 truck that I have, other than that it's a 305, when the same space/weight package under the hood should have been a 350 from GM, and for the same cost.

 

Is this a joke? It HAS to be. When you say stuff like this, you lose credibility. There is NO shortage of Chevy 350 blocks on this planet.


I don't doubt that you made a 300 horse 305....no one has debated that pretty unimpressive point. But there is no meaningful fuel economy in a 305, and you can buy 350's all day long from u-pull-it yards for ~$130. ALL DAY LONG. In fact, you could use that ****-box 305 someone gave you as the core!

Is this a joke? While I'm ALL for getting the most displacement out of a package size, cost also matters. In 4 sentences you "might as well'd" from a $150 short block to a combo costing thousands.


Does this actually need to be answered? Come on, man. Let's get real.

 

We are looking at HP but TQ is where the difference is made up for on the 350. OP said he ran a 13.6 spinning horribly with the 350 car. Id say that car may run a 13.2 on a perfect pass. The 305 car on a perfect pass may run a 13.9 on its best day I would imagine.

 

Well lets see....GM claimed my 97 350 made
245 hp @ 4,600
335 tq @ 2,800

GM claimes the 98 305 made
230 @ 4,600
280 tq @ 2,800

55 ft/lbs difference at lower rpm but the torque curves then converge and become much closer; given the 15 hp difference at 4,600 rpm the 305 is a scant 17 ft/lbs less than the 350 at 4,600 rpm. I am sorry I do not see 20-50 ft/lbs of torque making for 20 mph more speed climbing a grade. Not only have I not seen that much difference between a properly running 305 and 350, I also have a Nissan Pathfinder with a 4.0L V6 that I also tow with. Its rated like 288 tq @ 4,000. It has a 5spd Auto behind it with a 3.15 rear gear. With 6,000 lbs behind it, it will hold 70 mph in 3rd gear at ~4,000 rpm going up the steepest grades. The Jatco 5spd has very similar gearing to a NV3500. Not towing that 4.0L will climb a long 6-8% grade at 90+ in 4th.

I do not disagree with the fact GM could have put a 350 there. They could have easily put a 6.0L anywhere a 4.8L or 5.3L was as well. Then GM could have been bashed by every car magazine article writer for not offering more than 1 engine option. Something every one of the writers have done to the Nissan Titan since 2004 because Nissan put the big punchy 5.6L in every gas Titan.

I had a L30 vortec in an AWD Astro van as well with the factory 4.3L torque converter and 3.73s. On dry pavement the little 305 would bark all 4 tires from a stop. i towed a pretty heavy boat with it as well and the AWD setup with a V8 over the front wheels really made it nice pulling the boat back out on moss slick ramps. 305 did a great job moving it around unloaded or loaded with 4 adults and the boat.

 

I guess you should come down and scout the pick and pull yards down here. The mass rebuilders snag them as fast as they come into the yard. I was at several wrecking yards here a few weeks ago. I ran across exactly 4 sbc powered vehicles and none of them were 350s. The yards have loads of 4.8s and 5.3s though and not a 6.0L in sight. If the vehicle had a 350 in it, especially a Vortec the motor mounts get torched and the engine is long gone.

 

Just because the 350 makes more torque does not mean that the power can be put to the ground. There are numerous instances I have cut low-speed power by retarding the timing curve at lower rpm and gone quicker.

 

255. Not 45. 55.
That's a 25hp/55tq diff. That's a pretty meaningful difference in both numbers. Is that a diff you can feel/use? Hell yes it is.




Look harder.


IDK what to say....try towing a bigger boat? High elevation?
Back on point though: A-B comparison, 305 don't do so good. Building engines? Build a good-bottom-end 305. Bad bottom end? Get a 350 for the same money. This stuff is pretty clear and obvious and doesn't need to be complicated with subjective stories about Astros and camper trailers.

 

97 5.7L Express is rated 245 hp not 255 hp.

That is 15 HP and 55 TQ. As I have also said you once you hit 3,500 rpm like climbing a steep grade there is no difference at all. 17 ft/lbs is almost not even noticeable when it is spread out over 10,000 lbs. If you are noticing some huge difference you most likely have a plugged cat or low fuel pressure.

 

Why wast your time on a used up 350 when you can build a 383 or 406?

 

Covered, above. MONEY.

Just like the 305/350 change over point covered above, same goes for a 350; if you got a 350 w/a bad bottom end? 383. No brainer.

Like you got some junk 305's for free, I got a 400 for free. So? Am I building a 305 or a 350 out of it? Obviously not.

 

Who here, has talked about the F'ing Express Van??? NOT ME.

255hp.
Read the first paragraph. 255. That's a two, five-five'r. :yesnod:
Here's ANOTHER

And holychit....mang! Even YOU quoted 255hp....right here on this very forum! Wow, man, wow.

It was 255hp in the truck that I cited, that started you down this irrelevant rabbit hole. 255. Two....55.


You're struggling with reading comprehension. No plugged cat. Fuel pressure is fine. I've had this **** box for about 5 years now...nothing's changed. The problem is the hp and the tq; there isn't enough of either.

 

I will say now that I have had two different 383s and a 6" rod version, I am stuffing the longest stroke and rod practical in whatever block from now on. It makes more sense $ wise to get an aftermarket rotating assembly then it does to recondition the factory stuff.

Something you might actually like if you find another 400. I was payed to build, install and tune a very mild vortec head 406 under the vortec injection in a cutaway van RV. Way better running then the 350 Vortec even though the 400 had a flat tappet 214/224 cam and stock 22cc dished pistons. Made close to 500 ft/lbs at 3,000 rpm on 87 octane. Granted that torque would destroy every piece of your 98s driveline with ease.

 

Its 245 not 255. Get it through your thick skull. I used the comparison between the 305 in my Tahoe and my Astro van to the 350 in my Express van. The 97 Express is 245 hp not 255. PERIOD. The 350 in my 97 made 180 hp and 250 tq at the tires when it was stock. My TBI 305 with headers made 181 hp and 268 tq at the tires. 245 hp is the factory rating in GM Heritages information. The 305 Vortec had plenty of torque and hp to pull a decent load from sea level to 8,000 ft when I have run them. Not much difference from a 350. I also observed 2-3 mpg better in almost all highway driving with the 305 vortec. If your 305 is struggling put some headers on it. 305 with headers will make more power then a stock 350. The Vortec log manifolds flow like garbage.

 

Because MONEY.

400 blocks are getting REAL hard to come by these days, and people who have them don't give them away as just being "some old 2-bbl turd out of an Impala" anymore. The few that are left are just as prone to all the 70s quality control problems as any other 70s blocks, making them a total CRAPSHOOT anyway, at best; just as they have always been in that respect. In 1995, yeah, that was the way to go; in 2022, not so much. Great for those of us who already have them, but not applicable as "advice" to a beginner. Just because I built one for myself 40 yrs ago doesn't automatically mean that it's The Right Thing for someone else to do TODAY.

383 requires different pistons, different rods, and different crank, in some combination or other. (crank always, the other 2 you can pick one or the other or both) MONEY.

350 is simple. Go to the junkyard, buy it, DONE. You already have the crank, you already have the rods, and the pistons (if even NEEDED) are the single most common part # in every piston mfr's product line and therefore the easiest to get and least costly. Then whatever it needs, costs the same OR LESS than doing the same things to a 305; but you get to enjoy the effect of COMPOUNDING as described above. Making a 305 economic suicide.

But of course, ANYTHING in a van is TWICE as good as ANYTHING in ANYTHING else; the magical wonders that seem to happen in your van (its engine compartment that is), both here and on other message boards, never cease to make me smile. I don't generally bother replying to anything you say on any forum because arguing with an idiot leaves bystanders wondering which is which, and if you don't get any oxygen from anyone else, that whole situation remains obvious to all. But this time, since you actually ASKED a legitimate question AS IF you wanted to learn something instead of just being a blowhard, I am choosing to answer.

Have a nice day!!

Frankly, Tom hit the head right on the nail here, about the 305.

 

^That^ guys GETS IT.



My "thick skull"?? Wow.....Use your eyeballs, you numb nuts. How much spoon-feeding do you need?


No one...and I mean NO ONE, gives a *** about your stupid, retard-bus van. NO ONE. Here's what you ACTUALLY did:

You rebutted MY point about two identical trucks that I've had/have. One has a 220hp 305. The other, had a 255hp, 350. You tried to rebut that by telling us (in post #67) that you you don't believe that the "15hp" difference would make the performance (hill climbing) difference that I cited!!
So yeah....the power matters and the power of the truck that I was citing in my comparison, and you were trying to rebut is???

 

Given junkyard 350s are practically impossible to find in 2022 since they were last used in a road going vehicle 20 years ago in the US and people want ~$1,000 for a questionable core now days. Dart SHP block looks better all the time. My last bare 880 block came already machined, stroker clearenced and ready to go from Summit at a very good price pre-covid. I noticed recently they did not even have any of them and it was listed as Not Available recently. At the time my machined block and whole rotating assembly including being balanced and pistons fitted with rod ends properly honed for pins locally was $1,600 for the 383. $1,000 for a core engine vs $1,600 for a stroker short block.

 

When Summit racing cannot even source a bare block, kind of shows they are getting harder and harder to find.

https://www.summitracing.com/parts/sum-150100-30

 

Ya just keep on rapeat'n the same old dog ****....even after you've been clearly shown otherwise.

OR...$124.99
Just because YOU can't seem to find 'em.....you better stick with 4.3's and 305's.

 

As I also mentioned spending 2022 time and money. A Dart SHP block is not much more $$$ compared to buying a $1,000 core, having it machined, possibly finding cracks, bad bolt holes, etc in a 20+ year old block. A Dart SHP cost the same $ as a 4.00 or 4.125" bore. My next performance small block will not be a GM block nor will it be a 350. In 2022 money Summit was $800 for a machined 880 block. Having one done locally would cost substantially more to get the same work done. Last I checked its about $50 a cylinder to prep, bore and torque plate hone a block. Align bore is $300. Decking is $150 a bank. Now you have $1000 core engine for a block as it likely has cracked, junk vortec heads with $1000 in machine work. Then you are probably going to run into a damaged crank and maybe a rod that has been destroyed when it spun a rod bearing. Not worth it to buy a 20 year old, 300K mile 350 to me.

 

As I said its location, location, location. Several mass rebuilders here snag them up. They never even hit the u-pull it yards unless they have a rod hanging through the pan. Been that way for 8-10 years here.

 

When I can drive 20 minutes and pull as many 350's as I want to, from countless yards, that's not what that shows me.

 

Well then? Solution for you is super simple: Play with 305's in mini buses!


255

 

245

My solution is an aftermarket 415 on my next build.

 

You don't know how to click links and read...do you?

 

You wull not find a resonable one within 200 miles of here. As I said places like ATK scoop them up. I bet half those Summit blocks came from every yard in a 100 mile radius of here. ATK is only 20 minutes from my house.

 

Honestly you do not know how to read. GM literature has it at 245. Further enforced by 180 wheel HP when others were closer to 200.

 

Whatever. Let's see it. My reading is fine, the numbers are readily available, I made it perfectly clear, then backed it up with a plethora of links....WHO can't read?? Truck was 255. I could hit you on the head with a "255"....and you still won't "get it".

Super. Play with short-buses, 4.3's, 305's.....enjoy the HELL out of that. As you were.

 

To say that a 350 "falls on its face" sooner than a 305 is just nonsense.
They both have the same stroke, and there is no reason that a larger bore is gonna cause it to run out of steam sooner.
A 305 is a detuned 350, and detuning never makes more power (of course we ARE living in the Twilight Zone these days in case anyone hasn't noticed)...

 

^^^Totally.

 

Well, if 350 blocks are so damn rare, go LS!! A whole 'nother can of worms opened now. I like gen 1 SBC's but I'd defect to LS's if the other side of the coin were a 305. I can only take denial of science so far.

 

With the same cam and same head flow the 350 will fall off sooner. Vortec 305 and 350 have the same cam from GM. You have to move roughly 12% more air per cylinder with the 350. Look at the dozen or so 4.8s and 5.3Ls that Richard Holdener has dyno'd. They share the same block, heads, and cam. The 4.8L makes its power at a higher rpm. Give. The same cam a 305 will make power just as high of an RPM as a 350 with less head flow and because it is smaller. Give them the same gead flow and the 305 will make power at a higher rpm then the 350.

 

 

Im no expert..but i would guess to say from looking at the dyno that the dz302 could run with the lt1 350 in a light car with deep gears. In the case of these stock type heads..Head flow limits the bigger engines ability to breath at higher rpm. Basic stuff!

 

Nonsense...

 

Nonsense? After looking at that dyno graph? wow Some people u just cant reach! the 302 revs out to 7k no prob! that a big deal...with the same torque than either the 327 or 350! boom! Deny the evidence! Now with AFR 195 heads...the 350 would win I'm sure.

 

I agree. I have the same argument with guys trying to put a "torque" cam in the 4.8L for towing. They fight me when I say the best cam swap for low end torque includes a 5.3L or 6.0L housing it.

 

Yes my 5.3 Silverado 4x4 is a noticeable improvement over the almost identical 4.8 one i traded in for. Similar mileage too.