can a 305 be a fast engine?

can u build a 305 to be a fast engine ? cause ive got a 305 and id like to put some money into it but everyone on here doesnt seem to like it,"although mine seems plenty fast".
and if i can get good power what do i need to do to get it ?

ps. somewhere i read about a guy that couldnt even do a burn out on dry cement with his 305, is this true?cause mine can do huge burn outs?without any brakes or popping the clutch!

Well, as far as upgrades...it depends on how much money you want to dump into it. Id say things like headers and catback systems are a go, but once you start getting involved in cams and such, you might start second guessing yourself as to why you didnt just do an engine swap to a lt/ls1 or something. Try a few searches.

305's are the worst SBC. You can get a 350 for cheap. I'd do a swap with a LT1 carb motor. If not you are making a huge mistake. But its your decision, as mods go Id do headers with cutouts right after the collectors. You dont the catback money back ****. A stout holly carb would help. The a 4.10s ring and pinion.
Thats a good start and would make a nice difference
Post any questions.

the engine doesn't neccessarily make the car fast...

500hp in a poorly set up car won't do crap.

300hp in a well set up car can do amazing things.

the problem with the 305 is that it doesn't have much for aftermarket high end stuff.
it's hard to make power without good flowing heads, which are pretty hard to get for the 305.
not to mention the nature of the bore/stroke makes it a poor canidate for extreme power.

now you could easily built a bulletproof bottom end, the best flowing heads you can find, stick a HSR on it and then a dual stage nitrous kit and make 500hp.

but strictly engine...much harder.

and you say yours seems to be fast...cause that's a relative term. going from a honda to a crappy base model 305 would probably feel fast. going from a 305 to a cammed LS1 the 305 would seem slooooWWWW.

as for the burnout...not much of a comparison. some 305s came with as little as 150hp i think, some with 225. some came with crappy 2.73 gears, others with 3.23s or 3.42s.
not to mention the condition of the engine.

if i did go for an engine swap which id like to how much money would it cost on top of buying the engine and tranny?"i can get the engine and tranny for free". but ive never done that major of work on my car before, and will certain engines be a direct fit or will i have to do major rigging?

it really depends on what engine and tranny you're looking at

a basic carbed small block 350 or similar and a 700r4 trans, or even a TH350 trans will fit with little extra work.

even some of the readily available fuel injected, turn key crate motors will bolt in with little trouble

i suggest you start with some basic mods that will help you learn and get familiar with your car. if chosen properly, they will swap over to most any engine you decied to run later on after you've gotten some knowledge.

and engine such as this FI 350 (http://www.jegs.com//cgi-bin/ncommerce3/ProductDisplay?prrfnbr=199564&prmenbr=361) would be nearly a bolt in engine, depending on trans type.

well like i said i can get the engine and tranny for free so i just need to figure out how to switch it and what ill need to make it fit, and i need to figure out which engine to get!
and would like a 454 or some other big engine fit cause if i do do a swap i want alot of power gains from it!!!?

thkzz :)

A 305 is basically a 350 except it has a smaller bore. Asking if you can make a 305 fast is like asking if you can make a 327 fast, or a 302 fast, or even a 427 fast.. heck, I can make a riding lawn-mower that would whoop some serious a$$.
So yes. A 305 can be made VERY fast.

If you call a high 13 sec 1/4 mile fast...then yes. If you want real speed, ditch the 305 and go LT1 or Ls1 and run low 12's with moderate upgrades.

I relize that I can make 400+hp EASY in an LT1/LS1, which is my main reason for wanting one. Plus, I will be getting pretty awesome gas-mileage :cool:
BUT.. in my current condition, as-is, I think I will be able to hit at LEAST mid 13's if not better.
Think about it; 300hp is 300hp, it doesn't matter if it's your LT1 making it or my 5.0 305 making it ;)

yea i agree, you can make anything fast...just depends how you put it together...

also it depends on how fast you wanna go? do a few minor things and you can get that car running high 13's with a 305 in it....then maybe get it down to like 13 flat with major upgrades N/A...but thats about it...350 blocks are cheap, if your gonna spend the money to build up an engine, IMO you should start with a good base..

then its all about practality...you can build a 12 second car, and get 5 miles to the gallon, the hard part is making it streetable...much like my car...this winter i was confronted with tons of ideas...i could've went the easy way, get an air gap intake, 750 carb, and cam, and boom i'd have a 400 hp+ motor, then thro some 4 10's in the rear and i'd be running low 12's without a doubt....but i opted for the HSR instead and probably have like 1200+ into my intake alone, opposed to the 400-500 total i'd spend on a carb setup...

its all about what you want in the end, and your gonna have to make comprimises between form and function...

What did you do to your 305 to get 300hp?

Eh.. theres a list and a half.
cammed it, some intricate head-work done, Performer intake, Performer 600 carb, custom 80-Series catback, hi-flow race cat, dual-snorkel intake, and some gold old Fashioned Headers. Oh ya.. and a new vacuum advance distributor.
If I want to bump that to 400+hp, I am going to get a dual-electrical high-output fan system, new lighter and hi-perf. radiator, possibly a Performer RPM Air-Gap intake, electric water pump, and I also have my eye on some nice heads :cool:

will any basic 350 fit in my 91 RS or will there have to be major modding?

Like I have said before there are 305 sprint cars that make 400 - 450 HP and last all season there all motor and quite reliabe. I mean I am one of the biggest fans of "Theres no replacement for Displacement" but any motor can be made powerful and "fast" it just depends on how good you are and how much you like to be different

305 and 350 are same block... as with all the sbc afaik so any will fit... a FAST 305 would be cool, but the same amount of money in a 350 would be much quicker... my 91 rs LO3 supposedly had 170hp/255tq from factory... but to the tires it was probably more like 150hp/250tq... good ole TBI powered! had the 2.73's but it was still quick (for what we had in high school) and could do decent burnouts... they were not really built for performance... nice cruising car though:) cant wait to put my 700r4 back in it w/ a good cam... somehow find some good heads for cheap...

Here's a link (http://www.goingfaster.com/spo/325_horsepower_305_cid_chevrolet.html) for how to make 325 HP on a 305. My recommendation for getting a fast 305 is the following.

-Get a nice cam, like maybe .460 lift or bigger and 218/224 or better duration
-Get a nice exhaust system, long tube headers, dual exhaust
-Nice ring and pinion gears, 4.10's are nice, 3.73's will work nicely too, fast acceleration
-Better heads, LU5 heads that came on the Cross-Fire camaro's are nice flowing, but LE1/LE2 heads are nice too.
-Bigger throttle body, if TPI, like 52mm or 58mm, depends
-A very nice tune
-A nice big intake manifold
-And just for safety, get a roll cage to support your frame so it doesn't twist. Along with a strut tower brace for the engine bay

I don't know, i just came up with a lot of that on the fly, so if any of that doesn't sound right, let me know.

ShibbyZ

If you got the money a big block is the best choice and its not put one in a 3rd Gen car. Its bolts in. And a big carb on it and that car would pull the tires off the ground, with a good big block and carb

94 red dragon u saying that a big block is a bolt in for a third gen camaro?

305 and 350 are same block... as with all the sbc afaik so any will fit...

Sorry man, the external dimension of the blocks are the same, as with all of the other gen 1 sbc's, but they are not the same block.

- Justin

94 red dragon u saying that a big block is a bolt in for a third gen camaro?
:eek: :lol:

#54 on the craziest things I've heard about thirdgens list.

hey insane how is that #54 on ur crazy list?

Dude, going fast is going to cost you money any way you look at it. Depending on what your starting with will determine how much you need to spend.

But honestly, if you want build a 305 then do it but be prepared to spend some coin.

If money is going to be an issue, then look for another option (350 with HSR, LT1 or LS1 swap).

hey insane how is that #54 on ur crazy list?

54 was just a random number I picked out. I just meant that someone saying a BBC will "drop right in" to a thirdgen is just funny.

well ive been doin alot of reading on here and i think after i get a paint job im gonna try to start building my own 383 stroker, just slowly but surely build up the ultimate engine with the highest quality fastest parts i can get ! :D

thkzz for all the info

It can be depending on how much$$$$ you are willing to spend.I used to have a 1988 irocz with a 305 tpi. Well I put a 335 stroker kit in it. Had a shift kit installed and some 3.73's and ran dead even with a stock 96 z28.I didn't even touch the upper part of the motor.Could've went faster with more money.But There is no substitute for cubes . Builld the 305 if you want. You'll have fun with it.But you can do alot more with a 350 or a 400. I mean what ever you will do to the 305 you will get better results from a 350.more cubes

I have rebuilt a lot of 305s for my camaros and firebirds. Most of the time it was because of the budget I was dealing with. When you start increasing the cubic inches other things come into play. Such as, carb sizes/computer programming, parts fitting, fuel injectors, accessory drives, etc, etc, etc. You have different issues with whatever decision you make.

But, here is the fun part. It doesn't take much to wake up a 305. The stock motor is very restrcted and a lot can be done with very little money. I have built 305s knowing this and have had a lot of success. Most people wouldn't believe me when I told them it was a 305 and that made me feel good. I had built something that a lot of people said couldn't be done.

I would like to get more in depth, but I don't feel like typing a 4 page reply. All I am saying, is what ever decision you make, choose it well. If you want to stay with the 305, which is what your original posting said, then there are a lot of things you can do to help that are cheap. Some other the changes will make a noticeable improvement and others not so much. But, I gaurantee you will have lot more fun with your car.

It doesn't take much to wake up a 305. The stock motor is very restrcted and a lot can be done with very little money.

Ding Ding Ding.. he's right. From the factory 305's are HORRIBLY restricted. Like dahaus said, it does NOT take much to really wake them up.

Thank you 85 305. There a lot of misconceptions about the 305 and all the smaller sbc poweplants. "There is no substitution for cubic inch", but I don't think we are trying to build a pro-street camaro. We are trying to build a fun daily driver with a budget in mind.

I almost forgot. I also built a stroker 305 as bluebyeyouirocz28 did. I had great success. I was fortunate enough to dyno the motor (329bhp and 380 ft-lbs). One caution though. I wouldn't recommend using the 400 rod combination with regular 305 pistons. Although the compression was raised, the power band seemed to be a bit short. I suggest putting the extra $$$$ into the silvolite pistons that can utilize the 5.7 inch rod.

Thank you 85 305. There a lot of misconceptions about the 305 and all the smaller sbc poweplants. "There is no substitution for cubic inch", but I don't think we are trying to build a pro-street camaro. We are trying to build a fun daily driver with a budget in mind.

Yes, a lot of misconceptions indeed. Although I agree with the "No replacement for Displacement" saying, again as dahaus said I am not building a pro-stock/Jonh Force dragster here. I am building an 18-year olds first car :D

Oh and btw, what all was done to your stroker car if you dont mind my asking? Is all you did was stroke it or no :confused:

From what I understand the worst part about a 305 isn't the 45 less cubes, it's the shrouding of the valve. Especially if you want to run larger valves. :shrug:

First of all, yes there is some concern with valve shrouding, but bigger isn't always better. The biggest and in my opinion is a 1.94/1.5 setup for a 305. If the biggest valves made were the best then people would complain about not being able to put big block valves in a 350. And since we are on the subject of heads. The only aftermarket head worth a damn that I have seen is the World Products S/R Torquer 305 heads. They are cast iron and have 1.94/1.5 valves with a lot more flow than stock. I have modified 305 heads for bigger intake valves and port/polish the runners with success, but I do not particularly recomend this. The stock 305 heads are very weak.

I have heard that Top Line has a set of 305 heads out, but they are going through a ownership change so everything is on hold with them.

Something I want to try is using the Vortech 305 heads on a performance motor. I have see an article, in I believe Hot Rod, where they installed a set of 350 vortech heads on a 305 in a camaro, with great results. But, I know the 350 heads have a shrouding problem on the 305. I wonder, if a person took a set of 305 vortech heads and put bigger intake valves in with some mild porting and polishing, would it be better? Somebody needs to try it. Vortech 305 heads are plentiful and cheap at the salvage yard.

As for my stroker buildup, here is the specs:

.030 bore 305 block
Elgin 3.75" stroker crank
Stock 400 rods w/ ARP bolts
Cast 305 flat top pistons
Note: I recommend you use 305 length rods and the KeithBlack hyperuetec pistons (I can't spell today)
Stock 305 58cc heads with 1.94 intake valves and mild port and polish
268H Comp Cam (Hydraulic Flat Tappet)
1.5 rockers
Weiand Stealth intake
600 Holley carb

Use the recommended rods and pistons, better heads, more lift with 1.6 roller rockers, roller cam, and attention to detail, and you might be pretty close to your goal of 400hp.

You better hurry though. You got me thinking and I might try this combination.

Thanks for spilling :D Good stuff. I was interested in a 305 stroker for a while, but I didn't think it would give me enough performance for the price.
But would you take World Products S/R Torquer 305 heads over the Vortec heads?

I don't know. I haven't seen any flow tests or examples with the 305 vortech heads. Now, if I were to compare the 350 vortech to the S/R Torquer on a 305, I would pick the S/R Torquer. They are specifically designed for use on the 305

I may be wrong on this but I thought even the stock 305 heads shrouded the valves? It's just because of the small bore?

I don't know all the measurements, but we are talking about less than a quarter of an inch difference in bore size. Yes, you will always have valve shrouding. It is a well know fact that head designs have inadequecies. This is why it is such a big topic. People are always trying to find that extra flow from their heads.

All I can say is installing 1.94 intake valves on 305 heads, with the 1.72 or 1.84 valves, will make an improvement on the dyno. One thing that most machinests do is open up the chamber on the shrouded side of the valve. They will grind out to the edge of the bore. This is common even with 350 and 400 heads. Try grabbing the modifying cylinder heads book and you can read all about these problem areas.

A quarter of an inch if HUGE amount in heads. Of course it's going to be less than that.

Have you seen such improvments (going from 1.72s to 1.94s) without anything else done? (porting, cleaning, cam change, etc) I can't imagine someone would actually dyno such a small change. I was under the impression those larger valves barely fit within the bore of a 305. :shrug: I remember seeing a picture of the whole problem awhile back on thirdgen.org tech section. I'll see if I can dig it up.

1.94's fit in 305's just fine. I believe that's what the aluminum L98's have and they fit fine on 305's :D

I had an 80 El Camino with a factory 305 (biggest engine offered for that car in that year). I put a fairly small Comp XE cam in it, Vortec heads, RPM Air Gap, AFB 625 carb, MSD HEI Dist., headers, shift kit, and 3.42 gears. That combo ran 13's. I also know they make a stroker kit for these engines...it takes them to 331 CID. As for the displacement argument, let's remember that 67 Z28 Camaro's are 302's. It was a mixture of 327 and 283 components. So obviously with the right parts small cube motors can sure run...and many to higher RPM's than their larger counterparts. That being said I put a 468 BBC into the car the following year and went MUCH faster.

Zach

BTW. I used the XE cam from Comp instead of a Magnum because of the way the intake ramp works. It basically fools the motor into thinking it has more compression by waiting until the very last moment to throw the intake valves open. So, with low factory compression even with 62-64cc heads, the cam worked VERY well.

I have a set of 305 heads, somewhere, that have been modified with 1.94 intakes. If I can find them, I will try to post a picture so you can see what I mean.

And to answer the question about dyno gains with just the valves, no I haven't tried that, and wouldn't suggest that. Here is why.

When you machine the seat for the bigger intake valves you will have a large lip, in the bowl, from the transition of the old size to the new. You must enlarge this area slightly to take advantage of the larger valve. And when I say slightly, I mean slightly. These castings are thin. That is why I suggested going aftermarket, if the budget fits. To add to this, you must also unshroud the intake valve on the cylinder wall side. If you just put 1.94 valves in and don't do anything else, it would probably run worse.

I recently built a flow bench and am wanting to do some comparison tests. Maybe this will better quantify the gains that can be made. We will see.

I do know that I am definately not the only who does this. I read about doing this modification many years ago in a Hot Rod article and many articles since.

Iansane, I think I understand your concern now. 350 heads, with 1.94 valves, have a clearance problem on 305s. The valves on 350 heads are a little farther apart from each other. Thus, causing a shrouding problem at the cylinder wall.

I simply think making a 305 fast would be a waste before any part for a 305 would be the same for a 350 as they are mostly the same. So why not spend the same money and have the 45+ cubic inchs. Much more power poltentional. You can find short blocks so cheap. So do yourself that favor.

Iansane, I think I understand your concern now. 350 heads, with 1.94 valves, have a clearance problem on 305s. The valves on 350 heads are a little farther apart from each other. Thus, causing a shrouding problem at the cylinder wall.

All SBC heads should theoretically have the same pattern of valves. They shouldn't be in different places. Otherwise stud girdles wouldn't work (or they'd have different models for 305 vs 350). So they problem you're refering to, is on all SBC heads.

I never thought about it like that. You're right. I have never really measured the difference. It was just a comparison thing and what had been told to me. I guess you got me there. I am going to have to put my foot in my mouth.

But, did you read the link, earlier in this thread, that shows a 305 buildup producing 325hp. It was pretty interesting to see the difference in the heads. And amazingly the 350 vortech head did the best!!!

Takes a confident guy to admit something like that. :)

I didn't get a chance to read it, lots of surfing and reading about turbos to do. :) What are the differences between 305/350 vortec heads? So they used 350 ones and got the best results? Were they milled down any to increase compression or what cc were they? I guess I should just read and find out. hehe BTW, I don't think any reasonable person discounts that any engine including a 305 can make decent power, it's just the effeciency (=cheap to make fast) that it does so. Plus there is a huge stereotype against them.

I also know they make a stroker kit for these engines...it takes them to 331 CID. As for the displacement argument, let's remember that 67 Z28 Camaro's are 302's. It was a mixture of 327 and 283 components. So obviously with the right parts small cube motors can sure run...and many to higher RPM's than their larger counterparts.

I don't know much about engine building, just from what I've read so I'm not the person to take advice from. But the comparing the 305/307 to a 302 is like comparing the camaro ss to the cobalt ss. They're two completely different animals. They have totally different rod/stroke ratios. The 302/327 lend themselves quite a bit better to high reving (from what I understand) because of their larger bore and shorter stroke. Nothing to shroud the valves at high r's. :)

You are right about the lack of comparison in the 327,302,305,307. They are all different. This is why GM made them. They are for different applications. The 305 and the307 were designed during the 70s and 80s, when they were in search better emissions and economy. The 302 was designed in the late 60s to be able to compete in the trans am series with the camaro. And, the 327 was put together for a bad ass motor. I don't know the exact reason why.

But, the question here is not what motor is better than the other. The question was, what can be done to the 305 for better power, and would it be worth it? My answer is use what you've got. That is if you are working on a budget. I have seen many 300 to 350 horse 305s with minimal parts and money.

If you have the money and the capability, I say get a LS1. The LS series of powerplants has to be the most impressive that GM has ever put out on the market. In my opinion.

Right, I was just stating the Laguna's comparison wasn't very accurate. Which you agree with.

Then the question comes into play. Which is more cost effective. Modding your 305 (eventually rebuilding it..?) Or just driving the 305 till it blows and save for a 350 build or building a 350 yourself. :) It's all in your end goals. If you never want to make large amounts of power then just stick with a 305 a mods. If you want to surpass 350-400hp easily (<--keyword right there) then save for a larger cube motor with more room in each cylinder for better air flow and a better rod/stroke ratio.

As for the displacement argument, let's remember that 67 Z28 Camaro's are 302's. It was a mixture of 327 and 283 components. So obviously with the right parts small cube motors can sure run...and many to higher RPM's than their larger counterparts.

It was the RS camaro that came with a 302 in 67 and 68. The 302 used the 4" bore block of the 327 (same as a 350) and the crank from the 283, the reason was becuase chevrolet wanted to win a series of rally races with a maximum displacment limit of 305ci (and they did!) and felt that the 283 was too small (Ford was running their 289ci). Anyway 305's are junk motors with junk cranks and junk heads. The 283 has one of the best ever made cranks, those motors will run 7500 rpm all day stock without hurting them in the least. The 4" bore block will go down in history as one of the best blocks ever made, please don't compare crap with crystal, the 302 is a legend the 305 is somthing chevy fans prefer not to talk about. If you put horse power to a 305 you will twist the crank. Yeah you can build them but why put more money into a motor to get less hp than you would with a 350 and then limit your hp with crappy heads and eventually blow it up after hitting 6500 rpm a few times.

The 305 and the 350 cranks are the same!!!! They are just balanced differently for the difference in weight of the piston!!!!!

The 305 and the 350 cranks are the same!!!! They are just balanced differently for the difference in weight of the piston!!!!!

Finally, this is what I said in another thread after the other guy repeatedly states that the 305 cranks are junk and twist. They are made from the same material, same process being made, and pretty much the same. Now I am not a 305 lover by any means, and you can certainly tell that by my other posts..but 305 had junk heads huh? What are you comparing these 305 heads too..AFR, TFS, Dart...? There are a couple stock 305 castings that flow pretty well really, and to say that the 350 heads and 327, 302 heads are better..I would wan't to know how they are being compared. Sure none of the stock 305 heads flowed as good as an aftermarket head. The Al L98 heads can't touch an LT1 casting, the LT1 casting can't touch a LS1 casting...what is your point? There are a couple 305 castings that flow pretty decent for what they are and would probably outflow alot of the 350 heads. 283's run 7500 all day long, thats super...its a commonly known thing that big bore small stroke cranks rev higher. I have seen plenty of stock cranks rev over 7000 and never have any issues.

Nobody denies that the stroked 305, or a stock stroke 305 will make less power than a 350. Thats his own choice. You don't need some crazy heads to support 400HP sorry, The heads that came on the LB9's with some work should be up to task for that really...and if he wanted more I am sure the TFS heads for the 305 would be super, or even the AL L98 heads would be sweet for it. The stock crank will be fine to over 400hp with a good balance, decent rods( factory or some cheap I beams), and a good forged lightweight piston. The excess weight than can be shaved off with a Eagle I beam, and a light piston will relieve alot of stress on that crank. With the right parts the 305 can make 400hp, can a 350 make more...yes. Can a 305 be made fast...well fast is a relative term I suppose....it may be fast to you, and not fast to someone else. To each his own, but Lynk stop being a hater.

I just looked at the specs on those TFS 305 heads. I can't wait to see some tests on them. I they are as good as I expect, then this would definately be the way to go with small bore motors. This solves all the issues with valve shrouding. I think I'm gonna start saving money.

A good set of aftermarket heads for a 305 would probably cost just as much, if not more than a 350 shortblock and vortec heads

But, a head swap is easier than an shortblock swap.

they are listing the tfs heads at about $900 and the world product torquer heads go for about $650

^So do you think that the TFS 305 heads would be better than vortec 350 heads for a 305? And what about the world product torquer heads compared to the Vortech 350's and TFS 305's?

I think that both the torquers and the tfs heads should be better than the vortec 350 heads. These aftermarket heads have a combustion chamber that is designed for the 305 bore. But, the link earlier in this thread showed us an extra 20 horsepower with the vortecs over the torquers. So, I'm not sure. I guess the only test would be a comparison of all three heads on a 305. Flow numbers wouldn't be a good comparison, because the vortec heads were tested on a 4 inch bore.

Hmm.. you have a good point. Why do you think that the Vortech 350's give a 20hp advantage over the heads *designed* to be used on a 305?

I'm not sure other than the vortec head has a small chamber and maybe it doesn't interfere with the 305 bore. I have a 305 block and some vortec heads here. I think I am going to look at how they line up sometime soon.

Well make sure you come back on here and tell us what happens :D

I thought is was only the early Z/28 Camaro's that had the 302's. . .

Anyway, there was a dyno test over 10 years ago that tested stock versus 305 Torquer versus TFS Twisted Wedge heads. The TFS's made the most power despite 2.02/1.60 "shrouded" valves. Hell, the intake valve almost touches the cylinder wall.

I had an '89 Firebird Coupe with TFS Twisted Wedge heads, ZZ3 cam (208/221), Edelbrock Performer TBI intake, Edelbrock headers, etc. . . that ran 14.20 at 97 mph. Not too bad, but a short block swap over to a 350 (no other changes - same cam, heads, etc. . .) netted some 13.30's at 106 mph.

Also, the Stock Eliminator 305 TPI and carb'd Camaro's that run stock heads, intake, quadrajet/TPI, bore, stroke, compression, etc. . . are running high 11's NA. But. . . Stock Eliminator LT1 cars are running in the 10.40 range.