first i am going to say i am wanting to build a 305. i have heard it all..... about junk motor and whatnot. im just asking an unbiast opinion on this. i wanna build this motor or very much like it. with execptions on that i want rollor motor(mine came with it) so im asking. would i have the same power curve with a 335 as i would with a 305 only higher numbers? another question. they say in this article that if they had higher compression and a rollor cam they would have gone with a more agressive cam. what would that be?

forgot to post link



http://www.popularhotrodding.com/eng...cks/index.html

You're going to get flamed for this but it's your motor so go ahead and do it but it will cost more to build a 335 than it would a 350. I have already laid it out here.

https://www.thirdgen.org/forums/tbi/...-synopsis.html

there's all the part numbers and prices you need.

ok ok yeah i have seen some of your posts. you sound like u really know what your saying. well this is my "plan"
get close to 400 mark with that build. i think i can do it. and here is the catch. i know ill get flammed for this too. but i want to do it. i have done research on this topic for about a year and a half so i wanna do it. tbi. its what i want. i was thinking the 335 because easy lower 400hp? robert i saw your parts list. would those parts give me similar power curve? i like the straight tourque and the high rpm power. i wanna set my car for a road race and some fun strip time. and this is the type of power and range i want.

You want to road race? where do you want your power to come in at? that would really depend on head intake and cam selection. Not to mention gear and suspension. 400 hp with a 305 TBI won't be easy. it can be done I believe but it will take ALOT of time and tuning. Tuning being the operative word.
if it were me and I was going to do a roadrace car and I was stuck on a 305 stroker this is what I would do.

Ultimate TBI mods
Powerhouse "335" kit fully balanced.
Mildly ported vortecs with Z06 springs
Edelbrock RPM intake
ZZ4 cam with 1.6 rockers
T56
4:10 gears with a good posi
Take out even more weight than what I have now. (2900 flat)
And tune the hell out of it.

that should give a strong powerband and still pull like a beast in the top end.

Definition of opinion: "An opinion is a person's ideas and thoughts towards something which it is either impossible to verify the truth of, or the truth of which is thought unimportant to the person."

So, there is no such thing as an "unbiased" opinion. Having done both a souped-up 305 and a 350, and having done extensive research on the stroked 305 before doing the 350, I think I can at least provide an "informed" opinion.

Now, about this 335 thing (which is really a 334): 90% of the power gains were from what else was done. Meaning do those other things to a 305, and you'll get 90% of the gains.

From a money standpoint, spend the same $'s on a 350, and you'll get even more power.

The 334 makes no sense either from results obtained or performance $'s spent.

One of the original questions asked was about the powercurve - would it be the same, but only higher?

I think the answers is not exactly. Based on the rest of the engine (cam, heads, etc) being the same, I would expect that the torque curve would shift a little to the left (toward lower rpm), and a little higher, towards more torque. This is on the torque (y-axis) vs rpm (x-axis) graph.

Whatever minor restriction the rest of the components make is going to be a little more pronounced when you are trying to run 335 cubic inches worth of air & fuel through it than with 305 inches worth. So those restrictions will become significant sooner (at slightly lower rpm) and shift the torque curve left.

The torque curve moving a little higher (higher ft-lbs, not higher rpm), towards more torque is the benefit you get from the extra displacement.

These comments were on the torque curve, not the power curve. All I can say on the power curve is that it would come on sooner, I think it would also be helpful at higher rpm, but less of an increase than a ratio based on the displacements. (335 power would be less than 305 power x 335 inches / 305 inches)

I have never understood why 302 based Ford motors have always made good power compared to 305 based chevy motors. My friend has a 331 stroked from a 302 based Ford with a AFR 185 head, 10:1 comp and a .560 lift cam and the thing makes 450 at the crank. Now if somebody offers this setup on a chevy based 305 most people say it's unrealistic or a waste of time. What gives??

A Ford 302 has a 4" bore, which allows you to place reasonably-sized valves in it.

Its all in the bore. The 302 ford has the same 4.00" bore as a chevy 350.
The chevy 305 has a small 3.7??" bore.

The 305 still has a bigger bore than the 4.7 (287) in my Dodge Ram 1500. The 4.7 has a 3.66" bore, 3.40" stroke, and 1.89/1.46" valves. It makes 310 HP @ 5,650 and 330 ft/lbs @ 3,950. Its a SOHC V8, but regardless it is proof a small displacement V8 can still kick out plenty of power. Keep in mind these are SAE Net numbers and through power robbing, restrictive intake and exhaust setups.

The LS1 also has a smaller bore than the Gen I 302/327/350. Really hurts it, right? Obviously, there's more to it than just bore size.

The 334 would tend to lower the powerband.

ok first i want to say thank you for you guys not being so hatefull towards a lo3 "fan" robert, first i have always wanted to have a motor with high rpm capability but also make power up there. and the straight power curve of the build i showed you is something i desire i have always heard if its straight like that it will really give u a kick in the pants. as far as gearing i was still debating on either a 342 or 373 i didnt want to go too deep becase i wanna still keep it a nice street car, that i can take to the track(and autocross) i am aware that the higher gear would prob be best for the motor setup. and yes i plan on doing a t56 swap. but back to the motor.

i know there willl be lots of tuning with a tbi. but part of me is i guess you can say,,, drivin to do it? im sick and tired of ppl as soon as they hear tbi they think POS. and ppl saying oh..... or well i would.....rip it off,or grab a TPI. i want to show what they really can do. and ,i say this now, i think that it would be alittle fun learning exp tuning it. maybe get a little good at it?

and guys, thats the other reason i want a 305. EVERYONE it seems like has a 350/355/383 i wanna show what the little guy can do. i am aware that the 305 would prob be a better choice.



so robert after a little more explaining.. why those part choices? what numbers are we talking?(in power)

305 can definately make power and move.

https://www.thirdgen.org/forums/tbi/...ml#post3278199

THATS WHAT IM TALKING ABOUT AND ITS A TBI. the power is a little much too up for my taste but still BAD ***. fast, im a novice when it comes to the tune and computer but... the system u used controls the 4l60e what if i have a 700? and will change to t56 down the road? will it throw things out?


and what if someone supercharged that setup? thats the kind of power i want out of my 305. TBI.

I don't see anyone here asking about those engines. In regards to what was asked about a 305 chevy and a 302 ford it is the bore size that lends itself to the 302 making better power then the 305.

We are talking 305 not 350 bore size here. The ls1 has a larger bore then the 305

I'm not going to argue that those other motors are better motors with smaller bores but in the context of the question asked it is the bore that makes the 302 a better base to build of off then the 305. Now I'm not dissin the 305 either I've seen some great builds on this site that amaze me at the power gotten out of these little motors.

Honestly you'd be a lot better off using the money spent to build a stroked 305 on something else, like a better set of heads, or a new exhaust, or a 'bore kit', or anything else.

My point bringing up the LS1 is it is NOT just the bore size. The Ford 302 also has 4 head bolts per cylinder, which leaves more room for better ports. The Chevy 302 also had 4" bore, made a lot of power by reving high, but the same equipment on a longer stroke 350 would make more power. The same equipment on a 305 would make significantly less power because of the small bore shrouding the SBC valves, based on their location in the chamber.

Thanks for clearing that up!

Yeah, I've noticed a predilection towards ridicule of those who want to explore the full potential of the 305's..granted, you'll make more power sooner with a 350, but where's the challenge in that?

I honestly believe there's more in these engines than has been revealed.......more potential.

I have a .060 305(315) that mildly built, and it's progressing rather nicely...I say if that's what you have to work with, and are willing to put the thought and work into it, GO FOR IT.

I feel that with those Items together with a proper tune will generate a close 275-300+ horsepower at the wheels. CHP did a project 305 TBI car that dynoed in the 330 fwhp range a couple of years ago.
https://www.thirdgen.org/forums/tbi/...?highlight=chp

http://www.chevyhiperformance.com/te..._ii/index.html

I know the ZZ4 cam is smaller than what they used I know with better supporting mods (better exhaust, intake i.e) it is totally possible.

dollar for dollar spent on the 335 stroker, you could have had a 383, and made more power yet. hp per $ just doesnt make it worthwhile to build the smaller engine. just because you have a bigger engine does not mean that you will get inferior fuel economy either. the 383 will have to do less work to move the vehicle than a similarly speced 335, so it could very well get better fuel economy.

No, there's not. In the past 30 years thousands of fast 305s have been built, and their potential is well known.


Where's the challenge in any of it? There's nothing challenging about building a small block. It's all just a matter of bolting together a pile of aftermarket parts. Anyone with a Summit catalog and a credit card can do it.

If it's a challenge to get the same power out of a 305 as a 350, go make the same power out of a 350 as a 400, or make the same power out of a small block as a big block. You'll have something more impressive, and you'll have spent less money doing it.

that car tho is ultralight at 2700 lbs. Most street cars are 3200-3300. That car is doing extremely well for a 312 but in a heavier car its gonna slow down unfortunately. that car made 423 flywheel hp, i make 400wheel hp and i trap the same. My car weighs 3450 with me in it.

305 can make some decent power as that build shows, but in a average street car weight you need more cubes to make more power to get everything moving

But i'm all for a 305 or 335 build. Its different. Just dont expect something thats out of this world from it and you'll be fine

and im not looking for MASSIVE power just a good solid car. like that maybe at least 360 or 70 to the wheels. trap speed is not TOO important to me.
and pos a supercharger? i like that idea because in my mind its the ultimate mod.

with such a healthy goal, why shoot yourself in the foot by limiting cubic inches? start with a bigger mill, make the power at a more usable RPM, increase your drivability. jump in a car with a 283/283, then jump into a 300hp 350 car, if you cant tell the difference in drivability, there's something wrong with you.
turbo is where its at. you have to have exhaust anyways, why not add a little bit of a restriction to it for a gain at the other end. where a supercharger, you're adding a bigger parasitic drag to the front of the crank.

im kinda stuck with the 305. just because the bad mouth they get. i like doing something diferent. and a turbo for a tbi?
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also. if i screw my motor parts go through the turbo and i have to replace turbo and motor

Depends what goes wrong. The vast majority of failure modes don't involve anything solid going through the exhaust.

you're "stuck" with the 305 because of the bad mouth they get? that makes absolutely no sense whatsoever. you've been told the drawbacks of the engine, and they are very real, and dyno proven. if you want to build a brick house, are you going to start with a pile of legos? absolutely not! why would you think of starting with an inferior base, just to be different. that's just asinine.

i've been inside alot of broken small blocks, very rarely do broken parts show up in the intake or exhaust ports, most of the time you'll find them in the crankcase. if you've got broken parts making it past the exhaust port, you've got bigger things to worry about, your entire engine is already junk.

In a heavier car it will slow down, but not as much as they would lead you to believe. I ran a one time best of 14.73 @ 94.43 mph with a 2.38s 60' time in a 5,600 lbs fullsize conversion van with a much more low-mid range torque oriented 310 CID TPI Vortec under the doghouse. Stock 1,600 rpm torque converter, 3.08 gears, and 29" tall tires BTW. I could not launch at more than 1,000 rpm brake stalled or I spun the tires, despite 295/50/R17 tires.

Here is a time slip from said combo, but the engine was 220*F on this run in 95*F weather.

fast. so i know u are a fan of the 305? what is your official opinion of this thread?

We frown on building 305's for the same reason why we laught at ricers. They're trying to go fast with small engines, when we all know there's no replacement for displacement.

There's nothing wrong with building on the 305 that came in your car. The only time it gets to be a bad idea is when you have to remove it from the car and rebuild it. The cost of the 305 parts and the rebuild can easily go towards a 350 engine that is plentiful, inexpensive, and will provide much more power than the 305 will. A 350 engine is the best bang for the buck in small block chevy's. The reason why everyone builds 350s is because its so easy and inexpensive, and they work. Most every aftermarket small block chevy part is built with the 350 engine in mind.
Finding pistons for a 305 is tougher, and they're usually more expensive. Finding smaller valves to fit the 305 is tougher, and they're usually more expensive. Finding heads that work with a 305 is tougher, too. That's why almost all of us will tell you to build a 350 and not a 305.

there are bolt on L98's in the 12's. LB9 with same cam/very similar heads and same intake isnt even close to 12's. Thats the big difference of 45 cubes

I have a TPI 305 T-5 Trans Am vert that is supposed to be pretty rare and it smokes...the problem lies in that I have done the 305 to 350 swap on a 92 camaro tbi t-5 and it was awesome.I wanna build up my 305 to keep the original engine in it..

It's my understanding that a smaller bore(like that of the 305) with a longer stroke is more detonation prone, I think the wy I heard it was that the gasses are compressed more rapidly or something to that affect.

all I have ever driven was 305 and 350 cars and trucks, and I have to say that the 350s performed better overall. they rarely pinged they had more power (with almost identical camshafts)

I'm not bashing 305s by any means, they make great drivers, but if your pulling your motor to have it rebuilt you should really consider swapping in a 350.

on another not, ant bolt ons you throw at your 305 shold work with a 350 too, so you might consider getting an intake a carb (if your motor is carbed) and maybe a set of headers, all of it will work on both motors, it will help the 305s performance(not make it a monster by any means)and bolt to a 350.

from what I've seen, identical (other than stroke) 302s compared to 350s they make similar power, it's just that the 302 makes peak power at a much higher rpm than the 350 which makes it much more streetable. also the smaller stroke kills low end torque (less leverage, similer to turning a vehical with a tiny steering wheel, it's alot harder to turn than a big one!)

Does anyone know where to get the heads used in the article at the top of the thread? I search but couldn't find any prices. PHR is a fan of them, but why them over the 350 Vortecs or milled ZZ4s? If they were great heads and didn't need any modifications (but not $1200 like Trick Flows) that'd be awesome. By the way, now much does having heads ported tend to run? I know one thread suggested having the stock L03 heads ported, and that they were then comparable, or at least good. Thoughts?

The only stock heads worth anything are the Vortecs. And even they cost a ton in new springs and rocker studs, and a new intake manifold.

Stock iron f-body heads (both TPI and TBI) stink for anything over 300 flywheel HP. And the cost to refurbish them to use better camshafts is almost as much as a new set of good heads.

ZZ4 heads are ok, but they're just as bad as stock iron heads unless you pay someone to port them. Then again you're almost to the cost of a new set of good heads.

It's displacement that kills torque, not stroke.

but if you have two motors that displace the same amount and have comparable componets (heads, cam, intake, exhaust) , one with a long stroke and a small bore and the other with a short stroke and a big bore the motor with the longer stroke will have better low torque because the reciprocating assembly has more leverage on the crankshaft, thus more low torque. I'm not saying that a big displacement motor makes more or less to

No it won't, both engines will make nearly the same torque. If the displacement and combustion characteristics are the same, the cylinder pressure will be the same in each, but in the longer-stroke engine the piston face will be smaller, so there'll be less force pushing the piston down, which counteracts any torque multiplication of a longer stroke.

your right, I forgot about the piston surface area.