I have a couple engines laying arround. one is late sixties sbc 307 the other is 305 don't know what year. My buddy says the 307 is such a good engine. I disagree. so tell me what you think.
Compared to a 305, the 307 is a good engine. It has the same bore as a 283, and the same stroke as a 327. You can use heads with bigger valves, and rev it a big higher, compared to a 305. Although the 307 was never a performance engine, it was only offered with a 2bbl carb. It only looks good when you compare it to a real dog like the 305.
I am partial to the 307. Just because I have had two of them and currently run one in my plymouth. 307 's are known for soft factory cams (so change the cam right away). My 307 has power pack heads , edelbrock carb/intake and electronic ignition and runs real well. Burn-outs and high RPM!!! Oh Ya!! Basically its a stroked 283 from the factory. I've heard of people useing 305 heads on there 307 and its supposed to breath better than the power pack heads. Maybe do that and race me for pinks! lol
307s had something like 86cc heads, 7.5:1 comp. Changing heads and cam would be mandatory unless you drive an Olds 98 to church on Sunday. The blocks were better back then compared to the sh*t 305s. put the 307 crank, 350 block and you have a 327
they had 70,74,75cc heads but i'm sure the valves were small with that bore. Cheap motor if you need one.
You have the makings of something great there, but YOU gotta do the math and figure it out...take your time, and evaluate it all...it's not that hard. (sigh) ONE more time, people... 307 CHEVY: Essentially a small bore 327, came from the factory with unhardened camshafts so the lobes wore out very quickly...killing performance and economy. Know-Nothings labeled them as 'dogs' without breaking a seal to find out WHY. Nothing a cam swap and bolt-ons can't fix...as small blocks go, the 307 is as good or bad as any other. 305 CHEVY: Nothing but your beloved 350 with a smaller bore...torquey midrange motherfuckers that will flat STOMP your bullshit rumors and wive's tales about them if you apply an ounce of effort towards making them run right. It ain't hard...play to the engine's STRENGTHS...mild dual pattern cam, high rise dual plane intake, or a Torker II with the right cam, 600-700cfm carb, reworked HEI, headers...if you don't TELL assmunchers it ain't a 350 after that, they'll never KNOW. There's another option open to you, but explaining THAT scenario here would be like trying to herd cats or nail jello to a tree...but a clever, open-minded individual could figure it out...it's right there in front of you, Sir!
Basically, a 307 is a large journal 327 with a 283 bore. Since it's more oversquare than a 305, it should respond to the same performance modifications that the other '60s small blocks did. I've got to believe that a block cast in the '68-'73 era has more integrity than the later, lighter castings like many of the 305s were. A couple guys that have been working in the dealership where I work since the early '80s speak of a run of 305s in the mid '80s that cracked through the lifter valley. I've never heard of a 307 doing that.
Both can be made to boogie......I prefer the 307. After all...it is a small block and with the right mods......a 307 will rock on. Hack had a line on these in another thread mentioned above.
305 and the 307 are both nice little motors, setup right with mild modifications will get them performing. I think you'd be pretty suprised. I'd be happy with either one.
Both are engines with potential...the smaller being for the lighter cars and vice versa,As the 305 will out tourque the 307 at lower RPMS.....USE 305 4 BBL HEADS ON BOTH ENGINES AS THAT SHOULD YEILD THE MOST COMPRESSION-the cheapest HP gain you have.....
"There's no replacement for displacement" or so the old adage goes. Before I put a dime in either one, I'd find a good 4" bore block (302, 327, 350) and expend the exactly same money and effort required to do one of these. Just the fact of the larger bore resulting in less shrouding of the valves is going to contribute greatly to the efficiency and power of the engine and that's totally discounting any contribution larger displacement will always have on power production. About the only thing I might consider using from either one of these would be the 3 1/4" or 3 1/2" cranks themselves.
I suppose it all depends on your purpose for either of these engines. I've never even considered a "build-up" of a 305 or 307, always opting for the 4.0 bore mills laying around. I recently picked up a 305/700R out of a Chevy "Box Van" for $150.00;... only because of the price. That combo is perfect considering the current outrageous gas prices. I've heard nice exhaust set-ups on both 305/307's in "mild" street rods, & they sound real good. They sound like any other SBC;...I just have never known either of these to be "strong runners" in anything! I may use the 305/700R in a future "T" project because given the light weight of a T, (1600-1800 lbs. on average) they perform pretty well & are quick. To me, small bore & long stoke only equate to torque;...not power. Just my .02 on it.
I'd use factory 305 Vortec heads. You'll need a Vortec specific intake, but Vortec's are hands down the best performing factory gen I heads you can buy(and they're cheap at the pick and pull). Personally, I'd go with the 307. Either way, read this. It will open your eyes to the potential of the the lowly 305... http://www.goingfaster.com/spo/carcraft325hp305.html
All you have to do is slot the center holes out on the non-EFI intake and make angled shims. http://www.jalopyjournal.com/forum/attachment.php?attachmentid=153020&d=1137120645
Well my daily transport is a 81 el camino with the stock 305 and a turbo 350 when i got it it hwas stock with the computer and a 750 Quadra-puke. It loaded up and had no power So then i got a 450 holley carb and a little but taller holley Contender intake and now it runs a lot better and is torquie as hell still not enough top end it stops about 115 m.p.h and really likes to run around 2500- 3000rpm and gets 15 mpg might be better if it wasn't auto
I'm with Fathack. We used to run a .060 over 307 ( well a 283 with a 327 crank, small journal) in a sportsman with powerpack heads and it was no slouch. Whille the 305s did have some crappy soft metal, they have good potential too. I would go with the 307 and get the 305 HO heads with the 58cc chambers. Put 1.94 intake valves and do a bit of cleanup on them. They have an excelland runner design and are inexpensive.
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