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ok could you explain what makes a 307 so bad? ( and i really hope you try to explane it) is it the tiny 283 size 2bbl? or maybe the 1.72 intake valves? or the .390 lift cam ? or the smaller then normal intake runners on a 307 manifold? or maybe the 8.5 to 1 compression they had? lets say chevrolet offered a 307 with 11 to 1 compression,, a duntov solid lifter cam,1.94 valves in small chamber good flowing heads,a winters intake a holley carb? would it still be slob? ill answer it for you and the answer is NO it would not ! it would run like every other small block chevy less the cubic inches! my 17 year olds 307 is not a race engine by any means, but if you put race heads,race rods and pistons and a race roller cam it would be just as powerful as a 302! and actually a better combo for a race car with an auto then a 302 with identical mods! this is a fact! if you know anything about the old class Modified eliminator it was lbs per cubic inches like comp eliminator C/EA cars had automatic transmissions and used to run 312 small blocks! do you know what a 312 is ? yeah i didnt think so its a .30 over 307! i actually bought one off a comp eliminator racer and put it in my all steel 3250# 68 camaro and it went [email protected] mph with iron chevy heads and a 750 dp holley with a powerglide trans! and yes it was a 307 2 bolt main block!! do you base a 327 off the 210 hp 2 bbl version? of course not! you base it off the 365-horse version, why do you think modified eliminator racers used 283s 302s and 307 ? because the little motors made more HP per cubic inch then the big motors and the cars had to carry less weight! PROVE ME WRONG!
The factory could not offer heads w/1.94 valves in a stock 307 block because the valves breathing would be restricted because of the smaller bore.And that smaller bore is why a 307 cannot be a factory HIPo engine.
Why do you think the Hot Rodders and racers from the late 50's would bore their 283's out to make it a 301 ? It's because they bored them out enough that it was a 4 inch bore and that larger bore would get their engines breathing so they didn't run out of breath in the higher rpm's.

[URL https://www.jalopyjournal.com/forum/threads/301-chevy-question.966114/ [/URL]
why would they bore 283 engines out .125?if they didn't have to ?
Especially see the undated ad for the over the counter 301 V8 that cost $299 with exchange.
Read some of the reply's in this jalopy journal thread.Why would they make 4 inch piston
if you know anything about the old class Modified eliminator it was lbs per cubic inches like comp eliminator C/EA cars had automatic transmissions and used to run 312 small blocks! do you know what a 312 is ? yeah i didnt think so its a .30 over 307! i actually bought one off a comp eliminator racer and put it in my all steel 3250# 68 camaro and it went [email protected] mph with iron chevy heads and a 750 dp holley with a powerglide trans! and yes it was a 307 2 bolt main block!!
Any pictures ?
 
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That's the funniest joke I ever heard. :p The 307 was designed for fuel economy and low emissions while the 302 was designed as a Hi Perf engine so the Chevy racers could compete in SCCA's Trans Am series that had a 5 litre engine limit no matter what the design. Incidentally they won the series a couple of times too.Do you really think they could have won any of the trans Am road races with a 307 ?
In the early 70's we would see a beat up Chevy smoking like a 3 pack a day guy and me and my pals would bet whether it was a 307 or a 327 9 out of 10 times the smoker was a 307.Or the cam would have about 3 or 4 flattened lobes,time wasn't kind to those engines.
The 305 got all the design improvements they learned on the 307 but the only problem was the emissions specs had gotten stricter and CAFE standards had higher MPG's to meet.
Yes, I think Chevy COULD have won T/A titles with a 307 had they chosen to try. The longer stroke crank actually would have been an advantage at certain tracks. Who cares how the factory utilized a particular engine? What you can do with it is what matters, and for the most part none of these parts know what size engine they were put in. There is absolutely zero reason why any size small block Chevy would be more of a smoker or have more flat cam lobes than any other. Most of the smoking was valve guide seals and they are all the same and while the cam specs might be different, they were all made out if the material in the same factories. Most of the cam lobe failures back then were due to poor maintenance and improperly machined lifter bores anyway. What improvements did the 305 get? The ONLY reason it exited was because it could use the still in production 350 crank casting, and that long stroke could help get all of those underpowered slugs of the era moving. The tiny bore of a 305 is a HUGE hindrance to performance, yet just like the 307 it CAN be built to produce respectable numbers with the right parts. Some tend to forget that until the introduction of the 327, the 283 was Chevy's performance engine, and all a 307 is is a stroker 283. Until the supply of 327's made it a moot point, Chevy street performance guys would have KILLED for that.
 

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The factory could not offer heads w/1.94 valves in a stock 307 block because the valves breathing would be restricted because of the smaller bore.And that smaller bore is why a 307 cannot be a factory HIPo engine.
Uh, later 307's HAD 1.94 valves from the factory. My dad's 73 Blazer engine had them. I used 1.94's quite successfully on my 68 engine. Would valve shrouding hinder ultimate high end performance? Maybe, but most street engine guys build to impractical RPM numbers anyway. If I had a nickle for every guy that said "my engine makes X power Y RPM, and then I ask them when the last time they actually hit that RPM, the answer is usually silence.
 

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1970 SS454 LS6 11 second street car
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Fred, I think its both awesome and impressive that your son ran a best of [email protected] mph with that little 'ole 307 he built.
How cool is that!!
I have seen people running that ET and MPH with a pretty much stock 396 w/manifolds at the drag strip!
And that little 'ole 307 and Mustang are in street trim..closed exhaust and street tires
 

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307 specs:
Stroke:
3.25
Bore: 3.875
How in the heck is that such a long stroke ? its the same stroke as a 327 and a 305's bore is only 1/8 of an inch smaller than a 307 so if a 305 is tiny and the 307 is only a smidge bigger then WTH do you consider it tiny ?
 

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307 specs:
Stroke:
3.25
Bore: 3.875
How in the heck is that such a long stroke ? its the same stroke as a 327 and a 305's bore is only 1/8 of an inch smaller than a 307 so if a 305 is tiny and the 307 is only a smidge bigger then WTH do you consider it tiny ?
By the same token, a 307's bore is only an 1/8 smaller than a 350, but is considered junk. The reason I singled out the 305 is because I think it really IS too small for decent sized valves.
 

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I think people put too much emphasis on the numbers thinking well a 307 is close to a 302 and bigger than a 305 but that's not what is important with these SBC's.The 307 was built using the same bore as a 283 as an economy motor and a 302 was built using the 327 & 350's bore as a performance motor.
All 3 of those motors were built for 3 different reasons and thats where we should let it go.
This post was supposed to be about a guy's son running his engine at the track and doing good. I say let's let it get back to that.
 

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The beautiful thing about hot rodding is using what could be considered junk to make something unique and functional. And why not use something that would otherwise end up scrapped?

Sure if you're going all out, cubes are an easy way to get power, but it can also be fun to build something just to see what happens. A good running, well tuned small engine is just as fun as a not so good running big engine.

While the 307 may not be everyone's first pick, it is a small block Chevy after all and will respond well to the usual port work, cam, four barrel and headers. A .060 overbore and it's damn near a 327. Add some cheap 305 vortec heads with their small chambers for a bump in compression and you've got a great budget build.
 

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A lot of focus in the bore size.

Interesting, as the 4.8/5.3 LS use an even smaller 3.78 bore and 3.622 stroke and either with cam/headers runs real strong. I know the design is completely different and I'm assuming the valve angle is enough to negate the "shrouding" of the smaller bore in the 23° small block chevy.

Most fun, cheap engine I ever played with was a 4.8. Stock everything except cam/valvesprings/headers, went [email protected] in a 3400lb Camaro with a TH400 and 4.56 gears in a 9".
 

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Discussion Starter · #31 ·
If you don't like it, don't look at it (or comment about it)...

Why such high emotions about a CHEVY SMALL BLOCK, IN A CHEVY, doing well?

I applaud your work sir, enjoy your 307.
Its actually my sons 307 😂 but it is kind of odd that some get so angry over a broke college kids budget learn how to build a motor project ! 😂 But you know what, there were slower street cars there that day then his little junk 307! There were a few automatic 350 chevys with the same mods going 15s! i bet this car goes 13s in the cool weather ! And if you look at the combo section there are many 13 and 14 second cars here in the group! I have a 408, 355, and a 350 that i could have installed to go 11s or 12s but that was not the point here! And as far as small bores being only for gas mileage! I suppose 283-220s were for gas mileage as well!
 

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I think it's great that your Son did the swap, me I would have just run a 302 in that car for the ease of swapping stuff. Now look at all the Fox body cars with Chevy engines in them, warms my heart the Ford crowd thinks so highly of the LS and SBC's. At the last big car show I was at there was a kid there with a black Notch Fox body that had a 400 Vortec engine in it. I asked why he ran the Chevy engine in his Ford, his reply "I was never able to get in the 11's with any of the small Ford engines 1st time out the car ran 11.50's" He just had the usual bolt on stuff that got the job done. Like you Son's 307 Chevy getting the job done once again.
 

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I think this thread has turned into two different topics: 1) whether you love or hate the 307, and 2) what the OP did on this build.....with his son.

Obviously, I'm not a 307 fan....but the OP and his son did a great job on this build.....for very little money.

Nice to see old school hot-rodding still taking place in 2021 and 2022. Not every kid is attached to their smart phone, apparently.
 

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Its actually my sons 307 😂 but it is kind of odd that some get so angry over a broke college kids budget learn how to build a motor project ! 😂 But you know what, there were slower street cars there that day then his little junk 307! There were a few automatic 350 chevys with the same mods going 15s! i bet this car goes 13s in the cool weather ! And if you look at the combo section there are many 13 and 14 second cars here in the group! I have a 408, 355, and a 350 that i could have installed to go 11s or 12s but that was not the point here! And as far as small bores being only for gas mileage! I suppose 283-220s were for gas mileage as well!
Great job with the 307. I'm sure you'll be able to get it into the 13's with tuning. They are the same as any other sbc in that they are a sum of their parts. Unfortunately they were a base model engine and the factory gave them anemic cylinder heads and low compression. I've built a few for dirt cheap and they responded just like any other sbc if given decent heads and compression. All that hate on 307s means you can still pick up a decent runner cheap. I picked one up last year for $40. All it needed was a ball hone and new rings polished the crank and installed new rod and main bearings. Put a set of 416 heads on it and a small performance cam and its a lot of cheap fun. No its not a 350 but where I'm at $40 doesn't even come close to a decent 350 bare block much less something you can ball hone and throw a set of rings in it and expect it to run. It serves its purpose in getting my Chevelle 300 moving again while I finish my other projects.
 

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Discussion Starter · #38 ·
I think it's great that your Son did the swap, me I would have just run a 302 in that car for the ease of swapping stuff. Now look at all the Fox body cars with Chevy engines in them, warms my heart the Ford crowd thinks so highly of the LS and SBC's. At the last big car show I was at there was a kid there with a black Notch Fox body that had a 400 Vortec engine in it. I asked why he ran the Chevy engine in his Ford, his reply "I was never able to get in the 11's with any of the small Ford engines 1st time out the car ran 11.50's" He just had the usual bolt on stuff that got the job done. Like you Son's 307 Chevy getting the job done once again.
He wants to run a 302 (or any Windsor) but his car was a 4cyl car and he's a broke college kid so it was a matter of the cheapest route! but we did have the free 307 that he built a little over a year ago, so that was the cheapest way to go V8, that 307 has been in the corner on an engine cradle absolutely complete it even had break in oil in it, i had a couple of chevy transmissions laying around so all we needed was swap mounts and headers, the mustang crossmember bolted right up to the chevy trans it just needed a stud type trans mount,and the ford driveshaft just needed a 1310 turbo 350 slip yoke,the tin man mounts were $200 and the headers were $86 block hugger 1.5" shorty's from speedway (i think the 307 cast exhaust manifolds would flow better but they didn't fit) over the winter we will either put all the fresh pieces from the 307(cam, lifters ,timing chain, bearings, oil pump, intake, carb, heads) on a nice 71 350 core i picked up for $100 or put the 406 i have in it, so until he gets a full time job and moves back home Hes stuck with my chevy junk i have laying around! :ROFLMAO:
 

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Discussion Starter · #39 ·
The factory could not offer heads w/1.94 valves in a stock 307 block because the valves breathing would be restricted because of the smaller bore.And that smaller bore is why a 307 cannot be a factory HIPo engine.
Why do you think the Hot Rodders and racers from the late 50's would bore their 283's out to make it a 301 ? It's because they bored them out enough that it was a 4 inch bore and that larger bore would get their engines breathing so they didn't run out of breath in the higher rpm's.

[URL https://www.jalopyjournal.com/forum/threads/301-chevy-question.966114/ [/URL]
why would they bore 283 engines out .125?if they didn't have to ?
Especially see the undated ad for the over the counter 301 V8 that cost $299 with exchange.
Read some of the reply's in this jalopy journal thread.Why would they make 4 inch piston

Any pictures ?
PICTURES? of what my 10 second 307? no i dont have any pictures of that motor but i have plenty of the superstock camaro it was in if that would help with your doubt ! and the reason guys bored out 283s was to make them bigger motors PERIOD! you guys crack me up with these 302 chevy storys! 1969 Z-28s were high 14 second cars from the factory! if i put a 780 holley,a factory chevy aluminum intake,3.73 gears, dome pistons, a 4 speed, a windage tray with a trap door oil pan, and a solid lifter Duntav cam in this 307 i would be willing to bet this car would be a mid to low 13 car with the street tires and closed exhaust! it was not the 4" bore that made a 302 a great motor it was all the things i just listed above! look i never said the 307 was anything special and my sons 307 is not a race motor its his daily driver but i think its funny and kinda ignorant how some people base their hatred for a 307 on the 190hp version! remember this 307 ran 14.40 first time to the track through stock exhaust,on hard radial street tires,with an air cleaner in place on top of a stock qjet on a cast iron intake manifold,with 3.55 gears in a daily driver street car,not to mention this tiny motor is a 80,000 mile cast piston junk short block with NO machine work! maybe you and the other 307 haters should read this article to put the automatic 307 car going 14.40 on a hard radial cooper tire through closed exhaust with 2.00+ 60' time into perspective ! i would totally enjoy making you eat your words and doubts about how a 307 would run as good as any other sbc (short of the lack of cubic inches) but i have other projects and am not gonna waste any more effort or time in it. Vintage Dragstrip Test of Iconic 1969 Chevrolet Camaro Z/28 (motortrend.com) here is the factory z28 test artical and this is my car that had my 10 second john Guilus 307 in it, it ran SS/CS 10.29 @129.50 with a power glide trans
Tire Wheel Vehicle Land vehicle Car
 

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A friend recently bought a 302, destroked 350, it'll rev to 7,500 easily but I guess that's where the 302 shined per 5.0 limit, he also paid over $3K for it so not much of a Budget type engine, I think it's great you & your son built the 307, when I was 16-17 I made friends with the owner of a JY and can't remember all the parts I swapped on my 65 Impala with a 327, heads, intakes, dist., carbs. Wish I'd of swapped trans & rear gears but for a broke teenager I had a lot of fun on the Cheap, Surprised a BB Roadrunner once till a C clip & rear end gears blew out of the 10 bolt cover lol
 
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