Remember it's basically just a 350 Chevy with a smaller bore. Same rods and crank.
There were many 2 bolt 350's as well, but are still a different casting. The 305's are a lighter block by design (for economy).
Don't forget the 400 had Siamese cylinder bores. Need them steam holes for running 350 heads.Yes, different casting and of course much smaller bores. Conceptually the idea that it was a reduced bore 350 is correct, as they are the same architecture just like the 283, 327 and 400. But each variant had its own castings AFAIK, and so from a technical standpoint it is obviously more complex.
Don't forget the 400 had Siamese cylinder bores. Need them steam holes for running 350 heads.
Not exactly the same, the crank balancing is different between the two, 305's also had cast internals, and 2 bolt mains.
Not sure why the push for SAE30? This isn't 1983. Back in '05, I scored about 40 gallons of Delo 400 SAE30 from AZ for $.99/gal. It was a good deal and discussion back then revealed it behaved more like a 15W30 than straight weight. Still, not sure why you would not run a quality 5W30 lube in this stock 305. No extra ZDDP is going to save a physically inferior junk cam. As far as flat tappets go, there are millions of GM small blocks (and Jeep 4.0L/2.5L) engines running around on modern oil. I just don't see the value in running $12/qt oil in a 305.
Balancing was different on 400 small blocks. Not 305s. Also lots of 350s also had 4 bolt mains, the 305s just didn't ever come with the 4 bolt mains. It only mattered for higher RPM. And other than high performance or heavy duty versions most were cast. Rods and crank were the same part number for the same year 305/350.
I agree about the oil, my 240k 305 has ran on modern synthetic 0w30/5w30s for the past 40k+. No issues.
I didn't bother mentioning that 350's also had 2 bolt mains. There was no need.
400 small blocks are externally balanced. 305's and 350's are internally balanced.
The 305 crank and 350 cranks are not balanced the same. They will physically interchange (they used the two piece rear seal "442" cranks) but the 305 weights were drilled more to make them lighter for the smaller pistons and lighter duty rod.
Now that's an idea! Harder to pull a cam on a late model smogger than a '63 though. So much junk all over the engine.Those engines are incredibly cheap and effective to modify. If that was my car, I'd wish the cam would wear out to give me an excuse to add some power to to the engine.
Agreed about gutless. I had 305’s in my 86 Blazer and 85 Trans Am. Completely reliable and durable on Pennzoil 10w30 yellow bottle.My 83 305 has 240k miles. My last one (an 89 roller cam 305 had 332k miles). I've had several and known lots of people that had them, never heard anyone say anything like that. Gutless yes, unreliable...no. Remember it's basically just a 350 Chevy with a smaller bore. Same rods and crank.
They did have camshaft issues mainly 77-83. A friend of mine has the original cam in his 77 with 330k miles though. His dad bought new.
I run 0w40 euro in mine usually because it's my winter beater, cold starts at minus 20 or colder.
If it's low mileage I'd worry more about the cam. High mileage like mine it's either had the cam replaced years ago or it's not going to fail.