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![]() dr511scj_1:
The 307 is merely a 283 with a 1/4" stroker from a 327 (same bore as a 283).
While GM made a number of horrible SBCs in the emissions era (i.e. 305, 262, 267), the 307 is not one of them.
On the other hand, because it costs about as much to build a 283/307 as it does a larger SBC, spending the money on a small SBC doesn't make a lot of sense unless you're restoring a car, building to a specific set of class rules, or trying to build a high m.p.g. V8.
O you are right about building a bigger engine and getting more HP for the dollar, however I'd like to state that everyone says that here. We already know this to be true. People are building what they have, for their own reasons. I'll tell you right now, in my area you will not find many old 350's in salvage yards. I'm not gonna blow 1500+ dolaars on a Mexican cast hunk of scrap, crate 350 either. I'll build any first gen block that was cast here in the states, with American pride, and quality, over a cheaply cast engine desinged to turn a profit for GM. I have read posts where car crafters are having problems with heads cracking and head gaskets blowing on their crate engines. The worst thing SBC had trouble with in the smog era was athe valve guides wearing out.
Now onto your claim about horrible smog-era engines.
The 262(4.3L): Put into production in 1975 and 1976 only, this engine was designed for smooth driveablity that only a V-8 can give, pass emissions, and get fairly good gas mileage like that of the Buick 231(3.8L) V-6. GM missed, what they created was a V-8 economy, with 4 cylinder performance. This engine was serverely underpowered, and it was taken out of production in 1976. It has a 3.671" bore, and a 3.10" Stroke. Not many internal parts were interchangeable, maybe connecting rods, and pushrods, with other SBC in the family. Power was not present, at 110 HP @ 3600 RPM, and 200 lbs.-ft. of Torque at 2000 RPM.
The 267(4.4L): Put into production in 1978, until 1982, when it could no longer conform to emissions standards in California, this is once again a low-powered, economy version of a SBC. Once again GM missed their goal. Power output was a meager 125 HP, @ 3800 RPM, and 215 lbs.-ft. of Torque @ 2400 RPM. This engine has the smallest bore of the family(3.5"). It has the same 3.48" stroke of a 305, or 350. All journal and bearing sizes are the same as well, which means you CAN build this engine and interchange parts, fairly cheap. I am currently building one. My power output without a cam, or head work done is up to about 160 HP and around 4000 RPM.
The 305(5.0L): Often considered the most notorious dog of the family, this first gen block actually had close to 240 HP with T.P.I. I have witnessed STOCK versions of this first gen block run mid 15's in the 1/4. The guys lived in PA, had to pass inspections every year. I live in Ohio and know how strict PA is with their inspections. This SBC has many different variants, like the 350, and power ranges, based on production year and heads, cam, or carb. It has a 3.736" Bore, and the magical 3.48" Stroke. People have successfully built this engine to generate 376 HP on pump gas. Also read Car Crafts street build on the Ford 302. It has 392 HP, without a blower. That is only 16 more HP, and it has a 4" bore. This displaces the claims that you should not build any engine with under a 4" bore.
The 307(5.0L): My books only go back to 1970, but I think production began in 1968. Pre-smog era engines had 200 HP from the factory. Their actual power was 200 HP @ 4600 RPM, and 300 lbs.ft. of Torque at 2400 RPM. No high performance version of this engine was EVER produced. This was a V-8, once again made for economy, and personally I think it is a heap of scrap. It shares the bore of the 283, as you stated, with a 327 crankshaft. I feel the 307, could be a power producer, if it is built with a crafter who researches his build, rather than just putting in a HUGE cam, and a 4-barrel. With a 350 you can do that, you cannot do that with the smaller bores. Post-smog era engines the power was reduced to 130 HP @ 4000 RPM, and 230 lbs.-ft. of Torque @ 2400 RPM. Compression was also reduced to 8.5:1, down from 9:1. All applications have 2 barrel carbs. In 1973, power was further reduced, thanks to Uncle Sam and his dumb emissions standards, to 115 HP @ 3600 RPM, and 205 lbs.ft. of Torque @ 2000 RPM. This gave the 307 the LOWEST power output to displacement ratio of the entire SBC family. It was phased out in 1973 as well.
The 283(4.6L): Quite possibly the most solid SBC ever porduced. I have NEVER heard anyone talk about this engine as being "junky," "scrap," or a "boat anchor." It has the thickest cast cylinder jackets of the entire SBC family, and is the ONLY SBC that can be SAFELY bored out to 4.001", to make a 302. Only the 1958 to 1962 castings cna be bored this way. 1963 and up shouldn't be bored more than .060". It has the smallest stroke, at 3", which is shared only by the 302, and the 265. This engine can poop some high-end power, with the right build, from it's short stroke. Corvettes with these engines had great power output, with small 1.94/1.50 valves in the heads. I will get a 283 eventually to put in my Malibu, unfortunately the car will rust away before the engine blows up. Anyone who has a 283, and wants to build it, should. These are a very rev happy engine.
So to say the 307 wasn't a bad engine, may be somewhat accurate. In terms of performance and dependability, the 283 is far superior. What you gain in displacement with the 307's longer stroke, you lose in RPM redline. Look at most race engines, and how they are tuned. Most have huge bore's and short stroke's to maxmize flow through top-end RPM. Look at your laws of physics, as engine speed increases, engine torque decreases. The 307 will perform better in low-end off the line, but will lose ground in top-end. A 283 has the same bore, and smaller stroke. This means the build on it can handle more RPM. Since bores are the same, and volumetric efficency is what it is with natural aspiration, a 283 would out perform the 307 in High RPM power output. It'll will NOT outperform a 307 of the line, where low-end torque gets the vehicle in motion. So if the two engine were put on a dragstrip with the same build(Cam, pistons, cmpression, gear ratios, etc.) under IDEAL conditions. The driver with the 307 would ave more consistent power off the line throughout the 1/4. A 283 would respond a little slower off the line, but would start catching up in top-end, where the engine would generate more of it's power.
Guzzling gas and hauling ass, the true American way.
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