Why is it so hard to make a 305 fast?
What holds it back?
Im just trying to find the week points...

Please explain....

Thkzz

 

Simply put... the small bore. It severly limits the size of the cylinder head valves which let air in and exhaust gasses out of the combustion chamber. However there are guys running mid 12's with naturally aspirated 305 setups. It's not that the 305 is incapable of making awesome power but it simply has a disadvantage due to its size.

 

can it hit higher rpm's or anything special?
Make more torque...
Are there any pluses?

 

Well, one plus is that they have a decent crankshaft stroke of 3.48 inches. That is the same stroke size as a 350 motor. This is what helps the 305 make its ok low-end to mid-range torque. The 305's 3.78" bore can also offer better fuel mileage than a 350's 4.00" bore. The only other benefit is that a decent running 305 can be "initially" had for next to nothing. However the cost of performance parts for a 305 is about the same as any other small block V8. Therefore You might as well start off with a 350.

 

The 305 has many pluses when it's compared to other engines of the same size (307 Oldsmobile, most 302 Fords, 307 Chevrolet, etc.). Like most small pushrod, N/A, engines, it doesn't compare well to larger displacement engines like 350, 346, 427, 454 and up. It produces a lot of torque through the longer stroke and was never designed to RPM as high as a 302 Chevy that has a 3" stroke. It's a very respectable combination when apples are compared to apples.

 

The small bore limits the max size of the valves, as Rik89GTA said. That means there are very few cylinder heads that will fit, as most aftermarket heads have 2.02/1.60 valves. You need to stick with 1.94/1.50 valves.

Its ok to build up a 305, but once you have to remove the engine and rebuild it, its foolish to spend the money on it, when you can get a 350 for a similar price, or larger for more money.

 

does anyone on here have a built 305 thats making some good numbers?

 

My 305, nicknamed the Feeble305, was making 262 RWHP and comparable torque up until the time when I sold it. That correlates to 300(ish) at the crankshaft, maybe higher. It turned 101 MPH quarter mile times, 14.0 second typical E/T. It ran the original Quadrajet carb, with Edelbrock torquer intake manifold, gasket matched to the ports on the fully ported 305 heads. The heads had been opened up to host 1.94 intake valves. I ran an XE262H cam, used a 2400 RPM lockup-style torque converter, and shifted at 6200 RPM.

 

nice!
I have read that these 305's are actually pretty tough little motors, if built correctly could it handle a large shot of nitrous? and put it over 500hp that way?

 

500+ horsepower should be a piece of cake as long as You think it all through. First off, make sure You build a bottom end that can withstand the nitrous. Make sure You spend the extra money on a forged crankshaft, rods, and pistons.

 

if youre dead set on building a 305, go with all lightweight forged components. less rotating weight will help gain back some of the handicap of starting off with small displacement. faster revving means quicker ET's

 

im running a built 305 that i aquired from another internet friend. the motor is pretty much what i wanted to build and does exactly what i want it to do. i will agree, a 350 is the better way to go if your wanting strong #s. but for fun purposes, a 305 can be great. but if you want anything more than 480 lift and plan to do some racing of any sort a 350 is your motor.

 

This is the problem every time there is a discussion about the 305. Things are going fine, when someone has to leap off the levee into the Bull S***!

 

z28sorr, why dont you explain why that is a bs comment?
Why couldnt you just built the motor for nitrous and run a big enough shot to put it over 500 hp?

 

Iam in the process of building a budget 305.......
Iam thinking home ported heads and cam that makes good power to 6000rpms..
then have the 700r4 shift at 6000rpms....
So iam thinking home ported heads,cam,headers,intake manifold and a good 650-700cfm carb should make a good 215-230hp out of the little 305.....



Never know, maybe a 150hp nitrous with alky injection to keep the temps down to put me in the 350hp range.....