The Stovebolt Site Forums The Shop Area Engine Shop Straight 6 Guys are gonna hate me, but...

chevyvan77,
I live in the country so 75% of my driving is on gravel, usually around 40-45mph.
I do have a 4 barrel carb.
Overdrive would help but...oh well.
My rear end ratio is 4:11.
So going down the hwy @ 65-70mph is about 3,000rpm.
I've had tune-ups and really it runs quite well. When I first got it I drove it home on interstate and got 14mpg and was totally impressed.
I do agree though...why buy something new if the gas mileage is the same? As long as you've got a vehicle you enjoy I guess that's the most important part.

cubic inches are cubic inches, and weight is weight. whether you've got a 2003 chevy van with a 6.0 or a 77 with a 400 smallblock, you're still talking 5000 lbs. and 365-400 cubic inches of engine. I think maybe the new trucks have better fuel economy potential if driven lightly, but who wants to do that?

Hot Rod Dad,
I'm building the 400 for the 'Vette. It's going to be an odd hybrid fuelie motor - LT-1 intake manifold modified for standard-flow cooling, probably with stock LT-1 heads also modified for standard cooling (cheap and flow well, especially with some port work). 5.7" rods are the most likely length. I haven't decided on pistons, but I don't want to get over 10:1 - 10.5:1 compression. This will all be backed up by a 5- or 6-speed manual. It should be quite fast, with plenty of torque -- much better than the late '70s smog-era L48 in there now.

Flat cams in 305's, how about 350's? I worked as a mechanic in a school bus garage for a time when construction was slow in this area.The company got about 25 brand new 1980 one ton dualy van school bus conversions,all 350 powered.Before 10,000 miles,half of them had wiped out cams using the 10/30 fleet oil that previously caused no problems in earlier 350 powered small buses.One bus actually threw a rod on the first school run it ever did.GM tried to ignore the problem,but for sure it was a cam quality problem.
This school bus contractor company wouldn't buy full size Chevy 350 powered buses cause of cam problems in the past from heavy duty use.
From what I heard from mechanics,Chevy small blocks often had cam failures when in heavy trucks.

whats the world coming to when you cant even rely on a chevy smallblock

Sawby, I have to agree, but I'll rely on any GM engine except that annoying little carbureted 2.8L V6.

I have been away for a while, so I'll just post to many things of what ya'll have said.

I have heard from MANY owners that the I-4 is WAY better than the 2.8 V6. I drove one with a 2.8, and I thought it was horrible.

While the 305 isn't the most powerful engine (because it wasn't meant to be), it's still a good engine for later guys (like me). For example, in 1973, it was HORRIBLE, but by 85, it had DRAMATICALLY increased. This of course isn't "pre-73" but it's an added point. I've got an 85 w/ a 305, and it's great.

So anyways Sawby, how much? I love my engine, but hey, a new engine is a new engine! Can you tell me some specs? email me or pm me, thanks!
Stephen Hardy

Evidently there were several versions of the 305 made.I have heard a lot of complaints on this site about them being underpowered.I had a 56 BelAir,that had a 305 high performance out of an 84 Monte Carlo.That little 305 blew the doors off of a lot of 350s.I never took the time to have it dynoed but it had plenty of power.

Hardy,

I didnt have the engine built and the guy who did doesn't remember too well. I do believe that it's freshly built though, because it runs flawlessly and quietly (leaky dual exhausts notwithstanding). I think if it had been driven in that bus for any length of time it would sound pretty dogged. Honestly this whole post could have been in vain because he may be wrong about it being a 305. It never made sense to me, I thought maybe he was dyslexic or something, but he sticks to his story so until I find the casting numbers or take the heads off I wont know. Horsepower, with the headers and the duals, I think could maybe be 180. It's only got a 1 barrel carb on it but it's got okay balls for a small block in a 13,000 lb. bus. I suppose if it's rebuilt it might not have a soft stock chevy cam, but who knows. It's a mystery motor, but it seems healthy. Put a bigger carb on it and tune it up and I'll bet it would run for ya in a smaller vehicle. I have to find a suitable replacement before I sell it...anyone got a 366 or 426 Tallblock truck engine in decent running ocndition?

With gas going up, you might want to reconsider that big-block upgrade. Run the 305 until it dies.

shouldn't take long

Good one haha

correction on the carb on my 305...it's a 2 bbl Rochester. Once again the information I got from the previous owner proved wrong. I could have a 350 yet.

I looked up the 305 specs that were originally in my friend's 1982 Trans Am that I just helped him rebuild a 330 horse 283 for. The 305 in 1982 was good for 145 hp and 205 lb-ft of torque. The torque was okay down low, so it may be a good economy motor for a truck. However, I don't know if it would make any more torque than an I6 would.

By the way Saw4by...I checked with my friend on that tall deck 427 in his garage. It is spoken for, I'm afraid. There are plans for that motor...sorry.

I rebuilt a 305 last year, and put it in our 73 C 10. The motor runs great, and has plenty of power for what we do. We usually haul a bed "full" of newspaper to the recycling place, the engine works great. Came out of a 77 Nova. My thought on 305's is they work fine for lighter vehicles, but when you move up to a 3/4 ton rig, better upgrade to a 350 so you dont put too much load on the engine, unless of course you have the right gearing and such.

- Shane

thanks for checking into that tall block Hot Rod Dad.

Shane as for your post, I think you're right about what the 305 is good for, but that said, I have a full length schoolbus with a 305 under the hood. Not for long though hopefully

lol, um....yes you should probably get a bigger motor, like a 454. Wow, a 305 in a school bus?

- Shane

the 366 and 427 truck moters are unbeatable for a bus or truck

In one of my dads trucks(GMC 7500) we built a 454 with (8 to 1) smog pistons RV cam stainless valves and 600 holley.
And his outher truck(Chevy C70)
has tall deck 427 it has 7.5 to 1 pistons factory grind cam and and 600 holley. It makes just as much or more low end tourq but mabe not qite as much top end power.
Besides it has factory forged crank and four ring pistons

Hey thats pretty cool, never heard of gas engine having 4 rings, bet it lasts a little longer that way and has more compression than normal.

- Shane

4-ring pistons cant help your mileage, but in a medium duty truck who's gonna know? my dream motor for that bus is a 427 tall deck, but I can't seem to find one, apparently they were rare compared to the 366.

Shane, I'm more concerned about the build quality and durability of a 305 than its power. they aren't very good motors from what i've seen and heard of them, and the stress of heavy duty operation will probably kill this engine quickly

I'm a School Bus Mechanic, here in N.Carolina, & at one time we ran about 50-60 1980 Chevrolet C60 School Buses(I purchased 4 of them myself). They were 350 powered, with Allison AT545 Automatics. The most common problem we had with them, was the cams, & that was only with about 10% of them. They had plenty of power. We still run 3, 350 powered activity Buses,'78, '80, & '81 models. So, other than the cams, they were pretty good engines.

Is that transmission a good one for a V-8 powered truck?

I have a 454 powered P30 with a TH475 behind it. Would the Allison be better?

Is the AT545 that Allison Slip-0-matic with no lock-up torque converter? I hate that transmission, haha, what a slug with a diesel in front of it. I cant believe a 350 could push a school bus around tied to that slushbox

I noticed this in the link provided by Xram:

Zinc is the amount of zinc used as an extreme pressure, anti-wear additive. The zinc is only used when there is actual metal to metal contact in the engine. Hopefully the oil will do its job and this will rarely occur, but if it does, the zinc compounds react with the metal to prevent scuffing and wear. A level of .11% is enough to protect an automobile engine for the extended oil drain interval, under normal use. Those of you with high revving, air cooled motorcycles or turbo charged cars or bikes might want to look at the oils with the higher zinc content. More doesn't give you better protection, it gives you longer protection if the rate of metal to metal contact is abnormally high. High zinc content can lead to deposit formation and plug fouling.

This makes me wonder, would a high-zinc oil help in an engine that was designed for leaded gasoline, but is forced to subsist on unleaded now? I know there are lead substitutes, but I don't know what they really are or how well they work.

Saw, I've got a 305 in my 64, runs great, I only use straight 30w oil in it. I had a 307 bored to 4 in. making it a 327 big journal, which I ran in my stock car for 2 years without any problems, then sold it to a guy that put it in his camaro with a tunnel ram and ran it for another couple of years, hard and it never expired..........resto44

I was thinking of straight 30, but I dont know about cold weather starts with it. I guess I can't have it all 7 ways, so there's gonna have to be a compromise somewhere