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What is a 305 really good for?

  
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What is a 305 really good for?

 
quasha3 quasha3
New User | Posts: 4 | Joined: 12/07
Posted: 12/24/07
07:08 PM

I just recently remodeled a 1981 Chevy Silverado. The motor company pulled my motor and said that I had a 305 in it so I went back with the 305 not knowing that everything that I wanted done to my motor didn't make any since. I have a racing cam, flat top pistons, and a set of heads thinking that my motor would be ok as far as performance. Did I make a mistake?? My first project and I didn't know. Someone please tell me what's up  

The_White_Knight The_White_Knight
New User | Posts: 2 | Joined: 12/07
Posted: 12/24/07
07:57 PM

305 can be made to make resonable power with the right parts, but power for $, shoulda done a 350.  
Summer : 1988 Pontiac Firebird Formula 350
-L98 350
-Th700R4 With shift kit
-3.73 Posi
-Ws6
----
Winter : 1992 Camaro RS 3.1

quasha3 quasha3
New User | Posts: 4 | Joined: 12/07
Posted: 12/24/07
08:06 PM

So what type of parts do I need? I have a friend who has a pro mod race car and he is detrmine to prove a point. that even though its not a 350 its still a good motor. I know Nos has been mention. He says tha the flat top pistons while hold nos spray better than a 350  

GibTG GibTG
Guru | Posts: 931 | Joined: 08/03
Posted: 12/24/07
10:27 PM

There's a lot of generalizations here with nothing behind them...

As we've discussed a hundred times on this board, a 305 can make 300 horsepower fairly easily with some modifications, such as: an aftermarket carb/intake, headers, and some cylinder head mods

Now, a 350 can probably make 300 horsepower just with a carb/manifold and headers. So if you only want 300 horsepower a 350 can save money. Now, if you want 400 horsepower the 350 will save A LOT of money!

I would leave your friend behind. He will chase his tail for no reason. It doesn't take an engineering degree to realize that with commonly available, stock-replacement parts you will never make up the deficiencies of the 305's design in comparison to a 350. That quarter inch of bore diameter and 45 cubic inches makes a very significant difference...

Plus, what in the world does he mean that flat tops will hold nitrous better than 350 pistons? That statement doesn't really make any sense, there's a lot missing but I can say that If he is looking at crown design before using a forging over a casting he will soon lose that 305 engine that he thinks he will change the world with, if he runs nitrous.  
~Gibs

Pontiacman Pontiacman
Guru | Posts: 1890 | Joined: 11/07
Posted: 12/25/07
06:31 AM

I would not run any amount of NOS on any type of piston other then a forged piston its just  not worth the chance of destroying the engine.Depending on how much power you are looking for the 305C.I. chevy small block can make decent power numbers I have pulled good power out of 305C.I. chevys before and did not use NOS but just the right combo of parts.What is the size lift on the cam in it now.  
Professional hi-performance engine builder
Horsepower sells Engines and torque wins races.
Pontiacman

GibTG GibTG
Guru | Posts: 931 | Joined: 08/03
Posted: 12/25/07
11:49 PM

Sorry to break this to you but there is a HUGE difference between what one person thinks are "decent numbers" and another thinks is "good horsepower."

The morale of the story should be, if your goals are to extract the most power per dollar possible of your engine, then don't use a 305!  
~Gibs

Pontiacman Pontiacman
Guru | Posts: 1890 | Joined: 11/07
Posted: 12/26/07
07:19 AM

Like I said it depends on how much power a person is looking for.Yes a 350 would give more power per dollar.The 305C.I. is more then capable of making good horsepower with the right combonation of parts.  
Professional hi-performance engine builder
Horsepower sells Engines and torque wins races.
Pontiacman

TheSilverBuick TheSilverBuick
Guru | Posts: 1227 | Joined: 02/06
Posted: 12/26/07
11:10 AM

I was reading Popular Hotrodding last night in their Engine master's competition some one built a 305 for around $2,000 that made I think 390HP.  I don't know how long or reliable that engine would be but it's there.  
-
The Silver Buick- '77 Skylark coupe w/ a Fuel Injected Buick 455&TKO-600, '72 Centurion Conv't - 455w/TH400, '67 T-bird 4Dr (suicide) w/428&C6. '69 Firebird replaced!

http://www.bangshift.com/forum/index.php?topic=6189.0

Pontiacman Pontiacman
Guru | Posts: 1890 | Joined: 11/07
Posted: 12/26/07
11:47 AM

I know they had one that put out 372HP one time I had looked and know that with proper tuning and better parts they could get more.I have built engines for a good little wile and was told by a buddy of mine that has been building engines alot longer then I that a 305C.I. Chevy would not be worth putting money in to for power until I took him for a ride in my 305C.I. chevy powered elcamino then he still did not beleive it was a 305 until he ran the numbers now he is a beleiver too and he is one of the older guy's and said its not how long you have been doing it it's how long you've done it right and both he and I beleive that.  
Professional hi-performance engine builder
Horsepower sells Engines and torque wins races.
Pontiacman

77elcamino 77elcamino
New User | Posts: 2 | Joined: 12/07
Posted: 12/26/07
01:10 PM

Things to consider are what you are looking for the truck to do.  If you want it to sound good, have decent low end off the line grunt, and get fair gas mileage stick with the 305.  The 350 will have the same sound, more power and suck up a lot more fuel.  When you open the hood, the 305 will look identical to the 350 so for eye apeal you gain nothing with the 350.  The main thing to consider is the right intake and carb.  An Edelbrock Performer is a good choice for a 305.  More aggresive intakes are too much.  Stick with a dual plane.  The next thing is, don't go overboard on the carb.  500 to 600 CFM is plenty.  On smaller displacement motors it is easy to overcarburate which kills performance.  Then go with an open dual exhaust system or a cat-back performance setup.  This combination will give you a nice runner that will not eat too much gas.  If you are more concerned with running stop light to stop light, or running as fast as you can down the quarter mile than go with all the displacement you can afford and dump the 305.  

GibTG GibTG
Guru | Posts: 931 | Joined: 08/03
Posted: 12/26/07
09:20 PM

Wow, talk about a brickwall...

What exactly is good horsepower? We're all dying to know.  
~Gibs

slowbowtye slowbowtye
New User | Posts: 8 | Joined: 12/07
Posted: 12/27/07
08:23 AM

Pound for pound, dollar for dollar, equally equipt, a 350 will outperform a 305.  As far as "Good Horsepower", I have an 11 year old Tennesse Walker, and a 13 year old American Quarter Horse.  I guess each would be considered one horse power but the Quarter Horse can easily cover the quarter mile quicker than the Tennesee Walker.  In my opinion, I would say the Quarter Horse has "Good horsepower".  Hope this cleared things up for you GibTG.  

quasha3 quasha3
New User | Posts: 4 | Joined: 12/07
Posted: 12/28/07
12:41 AM

I not tring to take the truck down the track or anything like that. I just want a little more power than what I have right now ( which is a v6) thats all I am really looking for, But maybe some where down the line i would like to replace the 305 with a 383 stroker.  

1987cp 1987cp
New User | Posts: 3 | Joined: 12/07
Posted: 12/28/07
10:12 AM

Several these things are important to consider before deciding how to build an engine, including vehicle weight, rearend gear ratio, transmission being used, and torque converter stall speed if using an automatic trans.  Heavy vehicles with "tall" rear gears (especially with ratios under 3.00:1) will tend to want as torque-oriented an engine as you can build.  This will mean a mild dual-plane intake such as Edelbrock's "Performer", a short-duration camshaft (perhaps around 200 degrees at 0.050" tappet lift), small carb such as Edelbrock PN 1403, and small-tube headers.  

A "racing cam" can mean a wide variety of things, most of which are not appropriate for street use; find out the exact specs, and whether your block is set up for a factory-style hydraulic roller camshaft.  Is it practical to run a factory-style rollercam like Crane PN 109815, or would it be simpler to use a (much cheaper) flat-tappet such as Summit Racing PN 1102?  Again, stick with short durations for good torque characteristics, keeping in mind that cams with powerbands starting much over 1,000 rpm may require a performance torque converter with a higher-than-stock stall speed if you're running an automatic tranny.

Head selection is also worth considering.  I've been told that *most* factory Chevy small-block head castings did not flow very well.  If your engine core is an older model, the heads can be ported to do whatever you want, but you may want to look into upgrading to later-model Vortec cylinder heads - here, keeping in mind that these use a funky bolt-hole angle that my limit intake selection - or even a mild aftermarket cylinder head.

Finally, of course, once you're done theoretically spending lots of money on trick parts to make your 305-powered truck quick off the line, there's always the question of whether the money wouldn't have been better spent on a 350.  If so, you may want to consider building the 305 as cheaply as possible and saving up for a more serioius build later on.  

quasha3 quasha3
New User | Posts: 4 | Joined: 12/07
Posted: 01/08/08
06:38 PM

Well I talked to the engine shop and they placed a rv cam and flat top pistons will that improve my horsepower  

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