mystery of the 307
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mystery of the 307
hey im only 19 and i have not been around the chevy sbc corner if you get what im saying... i have some questions some of you guys who know the ins and outs of the chevy small block could tackle.
is the 307 the same as teh 327?
why does the 71 307 produce 70 more horse then the later versions that remain carbureated?
what is the compression of the 307 for the first run of the engine?
are the 305 307 327 357 396 and 400 sbc engines all share the smae block casting?
any info will be greatly appreciated thanks.
is the 307 the same as teh 327?
why does the 71 307 produce 70 more horse then the later versions that remain carbureated?
what is the compression of the 307 for the first run of the engine?
are the 305 307 327 357 396 and 400 sbc engines all share the smae block casting?
any info will be greatly appreciated thanks.
#2
The 307 has the same bore as a 283 and the stroke of a 327. Chevy didn't make a 357 of a 396 small block. The 400 has larger main journals. After 1970 auto makers changed the way the rated engines. The swithed from gross to net. Also after 1970 automakers had to comply with stricter emissions standards.
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thank you guys for the info, i have some questions, i dont want to mention the blue oval but the ford 302 is well the 302.... in that there are 302 parts... in the chevy world can parts be switched over do 327 cams fit 307 blocks? and heads and intakes. or is it pretty much just a backlist motor that never really got any attention?
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you can interchange small block parts, like putting 305 heads on a 350. 307 IMHO aren't worth modifying, and with 305/350 engine easily attainable I'd set your sights there as a starting point.
Derek
Derek
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well i got the truck in and she started right up, its pretty health 307, the prior owner has done some whack ****, its running a 4barrel i think its a webber but its still running the 2 brl factory cam, it idles smooth, i dont think im going to be building this motor up i will prob settle with a mild 350 crate motor as for now though the 307 has plenty of omph to get the s10 running.
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#8
The 307, 327, and 350 are all the same. The difference is bore and stroke. Forget the 350 crate, punch the bore of the 307 to 327, and get a set of high flowing heads (double hump heads are cheap), and get a good cam, intake, and carb. It'll be cheaper than a good crate and I guarantee if you build it right, the 327 will kill most of the 350s you'll encounter and run with the rest. I have a built 327 in my '69 Camaro backed by an m21 and 3.73s out back and I have no problem against ls1s, lt1s, and 350s. Not saying it can't be beat, but it's a lot cheaper and the 327 really likes to rev.
#9
Originally Posted by CarelessAndImprudent
The 307, 327, and 350 are all the same. The difference is bore and stroke. Forget the 350 crate, punch the bore of the 307 to 327, and get a set of high flowing heads (double hump heads are cheap), and get a good cam, intake, and carb. It'll be cheaper than a good crate and I guarantee if you build it right, the 327 will kill most of the 350s you'll encounter and run with the rest. I have a built 327 in my '69 Camaro backed by an m21 and 3.73s out back and I have no problem against ls1s, lt1s, and 350s. Not saying it can't be beat, but it's a lot cheaper and the 327 really likes to rev.
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I wouldn't waste your time with a 307. The heads did not
have hardened seats. I got one in my '68 El Camino and the
valves were sunk in anywhere from 0 to 1/8". I put 305 heads
on it and it's run for 10 years, but it's still a weak little pig.
350 for sure, unless you want to go stroker.
have hardened seats. I got one in my '68 El Camino and the
valves were sunk in anywhere from 0 to 1/8". I put 305 heads
on it and it's run for 10 years, but it's still a weak little pig.
350 for sure, unless you want to go stroker.
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I just did my senior research on Chevy muscle cars and I've found that the 307 is a 283 block with a 327 crank in it? I think thats what I read. Anyways I'd get a 350 and spray it. my 2 cents
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WOW, thanks guys for all the info, the truck is running good but it def does not resemble anything close to the power a small block chevy is known for, as for building it up i wrote some emails out to edlebrock and well you guys are correct, i could slap heads on it but i cant get any serious lift out of the cam, clearnce problems after .450 lift. there for i will let her be, then a 4 bolt 350 and some spray, im looking for a dependable turnkey street dogger, that wont see teh strip but once a season. thanks for the info again
#14
look for an 87+ 350 block from either a camaro or firebird, or any sort of GM truck. make sure its a 350 block and not a 305. i say this because its a 2 bolt main with a factory roller cam. the 2 bolt mains can be splayed and they end up stronger than a 4 bolt setup, and the roller cam opens your cam options up but more importantly should make them cheaper as you dont have to retrofit anything. run a GOOD set of heads (no factory heads period as none are worth the money) with a decent sized cam with a good intake and carb combo and it will run good. make sure you match the heads/cam/intake/carb combo well. that will make for the best performer.
myself, im going with a 224/230 .560/.598 112LSA cam from combination motorsports with a set of patriot SBC heads CNC ported and a holley stealth ram with 52mm throttle body and maybe some 30lbs injectors. it will also have new comp lifters, hardened pushrods and 1.6 comp roller rockers. from what ive seen in the LT1 world ill need to shift around 6200 but im hopin to make almost 400hp to the wheels with a stock L98 bottom end and a t56 6 speed combo in my 91 trans am. ill be happy with 380+.
myself, im going with a 224/230 .560/.598 112LSA cam from combination motorsports with a set of patriot SBC heads CNC ported and a holley stealth ram with 52mm throttle body and maybe some 30lbs injectors. it will also have new comp lifters, hardened pushrods and 1.6 comp roller rockers. from what ive seen in the LT1 world ill need to shift around 6200 but im hopin to make almost 400hp to the wheels with a stock L98 bottom end and a t56 6 speed combo in my 91 trans am. ill be happy with 380+.
#15
Originally Posted by Z-Convert
I hate to say it but you are "close but no cigar" buddy. Possessing a 327's large journal stroke of 3.25" and the 283's bore of 3.875" it had neither engines potential. Unlike earlier 283's from the 50's and early 60's (which could be overbored .125" to a 4.000" bore), the 307's made from 1969-up cannot be overbored beyond .060". You can put a 327 forged steel crank inplace of the 307's cast iron unit but why bother. If you use a head with larger than a 1.72" intake you will have a problem with valve shrouding. .
Uhhhh..... Don't know where you got your information from, but the 327 that I built from a '71 307 begs to differ with you. not only was this block bored out .125 over but I can still go another full .060 over if I want. these blocks typically had just as much metal as their 350 counterparts, just their bore was not as big. This is not the first one of these I've built either, I love guys like you that think the 307 is junk, go ahead give it to me I'll just make another 327 that will blow your doors off. hmm another 400hp, that's just too easy with these. The small block heads will fit these, what's this about valve shrouding . The only thing you have to remember with the conversion to a 327 with the 307 is that you have to order the correct 327 piston's in the stock size, not overbored....Duhhhh. Now 305's you can stroke them to a 334 but why go through all that trouble unless you get the heads that can help them breathe. All types of engines can be built, just don't take the word of someone on a message board just because they think they know what their doing. Talk to a reputable machine shop and see what they say about what you want to do. Sometimes you have to find one that's been around awhile that will remember these tricks to save money.
#16
Originally Posted by jimmyblue
I wouldn't waste your time with a 307. The heads did not
have hardened seats. I got one in my '68 El Camino and the
valves were sunk in anywhere from 0 to 1/8". I put 305 heads
on it and it's run for 10 years, but it's still a weak little pig.
350 for sure, unless you want to go stroker.
have hardened seats. I got one in my '68 El Camino and the
valves were sunk in anywhere from 0 to 1/8". I put 305 heads
on it and it's run for 10 years, but it's still a weak little pig.
350 for sure, unless you want to go stroker.
Then have your local machine shop put in hardened seats, it's not that expensive. 305 heads are 54cc's no wonder it's a weak little pig, you'd be weak too if you couldn't breathe.
#17
Originally Posted by 1bdbrd
look for an 87+ 350 block from either a camaro or firebird, or any sort of GM truck. make sure its a 350 block and not a 305. i say this because its a 2 bolt main with a factory roller cam. the 2 bolt mains can be splayed and they end up stronger than a 4 bolt setup, and the roller cam opens your cam options up but more importantly should make them cheaper as you dont have to retrofit anything. run a GOOD set of heads (no factory heads period as none are worth the money) with a decent sized cam with a good intake and carb combo and it will run good. make sure you match the heads/cam/intake/carb combo well. that will make for the best performer.
myself, im going with a 224/230 .560/.598 112LSA cam from combination motorsports with a set of patriot SBC heads CNC ported and a holley stealth ram with 52mm throttle body and maybe some 30lbs injectors. it will also have new comp lifters, hardened pushrods and 1.6 comp roller rockers. from what ive seen in the LT1 world ill need to shift around 6200 but im hopin to make almost 400hp to the wheels with a stock L98 bottom end and a t56 6 speed combo in my 91 trans am. ill be happy with 380+.
myself, im going with a 224/230 .560/.598 112LSA cam from combination motorsports with a set of patriot SBC heads CNC ported and a holley stealth ram with 52mm throttle body and maybe some 30lbs injectors. it will also have new comp lifters, hardened pushrods and 1.6 comp roller rockers. from what ive seen in the LT1 world ill need to shift around 6200 but im hopin to make almost 400hp to the wheels with a stock L98 bottom end and a t56 6 speed combo in my 91 trans am. ill be happy with 380+.
This is the best advice I've seen in this topic.
#18
Originally Posted by char
WOW, thanks guys for all the info, the truck is running good but it def does not resemble anything close to the power a small block chevy is known for, as for building it up i wrote some emails out to edlebrock and well you guys are correct, i could slap heads on it but i cant get any serious lift out of the cam, clearnce problems after .450 lift. there for i will let her be, then a 4 bolt 350 and some spray, im looking for a dependable turnkey street dogger, that wont see teh strip but once a season. thanks for the info again
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Originally Posted by my68camaro383
The small block heads will fit these, what's this about valve shrouding .
Before you call BS and start posting things like Duhhhhh maybe you should realize what somebody is saying first.
#20
well of course any head will flow better on a larger bore, but what he said is that you can't go over a 1.72 inch valve, which is BS when you step it up to a 4in bore which is what a 327 is.