Why does the Chevy 5.0L / 305ci V8 have such a bad rap?

So what does the casting number/suffix code tell you? You can't mistake a 305 for a 350, those numbers tell you authoritatively. Why guess?

And why is the 305 maligned? Because GM tried to make it take the place of the 350. High(er) compression than all other motors of that era (9:1 when the 350's were ~8:1) so pre-EFI they already had electronic spark control (with knock sensor) to keep detonation under control. Since they were pre-EFI, and pre-Vortec, they had garbage chambers (just like any other motor of that era) so GM had to try real hard to get power close to the 350. Additionally, when GM started using the 305, they also continued using horrid rear gears (due to EPA mileage requirements) so the already lacking in torque 305 felt even worse than it really was.

The actual, physical downside to the 305 is it's bore size. The bores are so small that for real performance duty, the valves end up being shrouded by the cylinder walls, and you can't fix that.

I had a 305 in an '83 and had no belief it was ever replaced, or taken care of, as when I took the valve covers off it was caked in inches of carbon. It was horrible. Yet, I routinely held that thing in 1st and 2nd gear (3.08 rear gears, 700R4, and 31" tires, it was a slug) and it never failed on me, and would respectably get moving, but only if you weren't afraid to rev the piss out of it to get there.

Coupled with 3.73's and smaller tires, I'm sure the 305 wouldn't feel terrible. However, for every modification done to a 305, if you did the exact same thing to a 350, the 350 would make more power. And since the 305 was already lacking in torque in just about every vehicle GM put it in, using more gas/more RPM's to get up to speed didn't REALLY save any gas. FWIW I got the exact same freeway MPG with the 305 setup as I did with a 350 in the same rig, with 3.42's and no OD.

Edit: If you take out the city stop and go, I suspect you'll see it will run 16-18MPG on the freeway if you keep it right around 60MPH and use the cruise control. Doesn't matter what the gearing is for city driving, those motors will net 10-13MPG in those conditions regardless of tire size, weight, gearing, trans, etc. It's just a substantial amount of weight to get moving, coupled with a V8. the only noticeable MPG difference you see in these trucks is when you compare the 305/350, 6.2/6.5 diesel, and 454's.

Maybe, because it was designed to please , big brother.

Very poor computer controlled ignition.

Very poor feedback carburetor.

Very low compression.

Awfull valve timing.

I do have an 84 Camaro, with a 305, runs great.

I have installed:

A) Flat top pistons, and decked the block, to leave only

the head gasket thickness ( .040" ) between the piston

crowns ( Flat ) and the heads. That corrected the compression

issue.

B) Got a HEI distributor, with centrifugal advance and vacuum

advance. Modified the springs and got rid of the computer,

controlled ignition.

C) Got a Rochester quadrajet without the computer controlled

Mixture control solenoid, out of a car from the 70's.

D) Installed and advanced 6 degrees an older Chevy Camshaft

yes, you guessed it right the one used by the 327 of 350 H.P.

at 5,800 RPMS part number 3863151.

It has 221 degrees @ .050" and .447" of lift.

Reasonable Idle quality and revs up really fast. Have to keep an

eye on the tach, to avoid overrevving and dropping a valve, that

will destroy the engine.

Sure a 350, with the same parts would make more power, but I

get with careful driving 17 MPG in City traffic, not to congested

but with several stoplights along the way.

To me , there is nothing wrong with a 305, as long as you replace

the "smog", distributor, carburetor, camshaft and compression!.

I enjoy it a lot!. And is over 3 decades old. With a camshaft that

was released back in 1965.

Well, it sounds like someone yanked the original 5.7 and put a 305 in. It has a bad rap because of engine prejudice. Being old skool I can relate. A matter of power, cubic inches and brand pride. Back in the day people my age pooh'd the anemic 350 Chevy engine and praised the non anemic pre pollution emission laws 327, 396, 427 and even 307, 283 motors. Any praise for pollution era Chev motors was left to the still anemic 454.

Then the computer managed, fuel injected era came. The 350 finally became as powerful as the old pre pollution era Chevy motors. The 305 sedan rear wheel drive motor now the lesser brother.

The Chevy 305 is the same block as a 350 it is just a different bore. The different size boar did create some oil consumption issues on the 305 over the years when they would get up in the higher mileage bracket and they would develop a blue smoke on start up issue. Real important to keep your oil clean on either one of these motors. 1995 was the last year for TBI (throttle body injection basically a fuel injected carburetor) and was followed by the Vortec fuel injected set up introduced in 1996. I wouldn't say it gets a bad rap but it did have some known issues and guys that work on GM will agree. Not everyone had these issues it was mostly the people who liked to skip oil changes. These were not the engines to do that with nor is any engine for that matter.

I have a 94 chevy 1500 with a 305. The engine runs great, starts every time, but does burn oil. (It only has 47k on it as it is a funeral home truck) The only problem with it is it has no power. Our '90 Suburban with a 350 will smoke the tires down the road...this thing won't even turn the tires with a clutch dump. Dealer has always said that it was fine and that was the way it should run. Has gone thru 3 clutches so far from slipping it even in low 4 wheel with 1000lbs in the back.

I own a 98 silverado 165K miles stock motor, my dad has a 96 Sierra with a 350 and my truck has way more get up, you have to push the pedal down a bit more to get power outta his and his burns/or leaks a quart every 5K mine burns none. Probably mileage related though

I am a retired mechanic,the 305 engine in the z28 camaro 1986,had tuneport fuel injection and was a screamer,the throtelbody injection was junk ! The tune up and fuel system was the trick.

Your 350 truck serial number should have a "K" in the eight position, and I wonder why you were told it's a 305 as they look the same.

I am a mechanic and do not know of a disadvantage of that motor. All three motors are good motors. Just keep it maintenanced