V8 difference 307 or 350 ???

[brawley]

Im looking at a 1971 parts truck , I was told it has a V8 in it, before I take the ride over to look, how can I tell by looking at the engine weather its a 350 or 307, I can look up numbers, but wanted to see if you can tell by looking at engine??

[landy]

Since the same block is used for the 307 and 350 (and for many other small blocks as well), I don't think you can tell just be looking at them.

[jocko]

not that this will help you tell by looking - but if there is no engine listed on the SPID (and it has an "E" code vice an "S" code on the SPID), the base V8 was the 307. If it came with a 350, it would be listed on the SPID. Again, this doesn't guarantee the motor hasn't been swapped, just helps you confirm what it "should" have in it - or, at least, what it would have had from the factory.

[Mikeeal33]

Did any 350's come with a 2-barrel? I know the 307's did.

[brawley]

thanks for the info about the SPID, that helps....any info on the 307's im thinking about swaping out my 250 inline, not sure if that's much of an improvement or not....

[King Cary]

Look at the harmonic balancer, there is a size difference. Google 307 harmonic balancer and 350 harmonic balancer, that way you will see what I'm talking about and be able to spot the difference.

[69GMCLonghorn]

Someone touched on the carb... There were 2 barrel 350's, but NO 4 barrel 307's. So if it appears to be all stock and has a 4 barrel carb, it is a 350 (or something other than a 307).

[69GMCLonghorn]

Originally Posted by brawley

thanks for the info about the SPID, that helps....any info on the 307's im thinking about swaping out my 250 inline, not sure if that's much of an improvement or not....

Lots of people consider the 307's to be boat anchors because they're not as powerful as a 350. I'm not in that "boat" so to speak. No, they don't have the power of a 350 but they are good engines, and will definitely be a big improvement over a 250 I6. You can put a small 4 barrel and headers on a 307, get decent power, and better mileage than a 350 (maybe close to what your I6 gets since it won't be working as hard!). Just food for thought.

[54blackhornet]

I have a 71 C/20 with the original 307. It sat for twenty years inside a grain elevator building before I bought it. After rebuilding the two barrel carb and installing a HEI the engine runs like a sewing machine. Does not smoke or burn a drop of oil in 3000 miles. I believe the 307 receives bad reviews because the 350 is so much more common today. It’s also very easy on fuel. I use the truck strictly for bringing in fire wood. The low first gear in the original four speed is perfect when it’s loaded with wood.

[RustyPile]

Originally Posted by landy

Since the same block is used for the 307 and 350 (and for many other small blocks as well), I don't think you can tell just be looking at them.

This is incorrect information. the 307 has a 3.875 (3 7/8") bore, while the 350 has a 4.000 (4") bore.. Basically, the 307 is a stroked 283 with the same stroke as 327.. A 350 is a stroked 327 using a 3.47 stroke crank. Meaning a late 327 and 350 are the same block. The short lived 302 had a 4" bore and the same stroke as a 283... The only thing in common with ALL these engines was the rod length -- 5.7".

[MARKDTN]

Originally Posted by RustyPile

This is incorrect information. the 307 has a 3.875 (3 7/8") bore, while the 350 has a 4.000 (4") bore.. Basically, the 307 is a stroked 283 with the same stroke as 327.. A 350 is a stroked 327 using a 3.47 stroke crank. Meaning a late 327 and 350 are the same block. The short lived 302 had a 4" bore and the same stroke as a 283... The only thing in common with ALL these engines was the rod length -- 5.7".

That post is 10 years old, but perhaps what he meant was that all large journal small blocks (except some 400 with more freeze plugs) look similar and are dimensionally the same outside. 2bbl vs: 4bbl is a good clue but in the last 52+ years of these trucks a lot may have been swapped around. Oil dipstick location helps with later blocks as does 1-pc rear seal if you can see that if it's on the ground with no flywheel. Honestly the stamp pad is the best way to tell what it is without too much work-assuming it's never been built and decked.

[RustyPile]

Originally Posted by MARKDTN

That post is 10 years old, but perhaps what he meant was that all large journal small blocks (except some 400 with more freeze plugs) look similar and are dimensionally the same outside. 2bbl vs: 4bbl is a good clue but in the last 52+ years of these trucks a lot may have been swapped around. Oil dipstick location helps with later blocks as does 1-pc rear seal if you can see that if it's on the ground with no flywheel. Honestly the stamp pad is the best way to tell what it is without too much work-assuming it's never been built and decked.

True about the age of the post, but be honest with yourself -- you have not the slightest idea what he meant, only what he said. What I stated here was also correct ten years ago and is still correct today. None of that alleviates the fact that the post was incorrect. This is a prime example of how false and untrue information gets spread over the internet.

I started building race engines around 1962.. The favorite sbc for some of the racers in those days was a Chevy 301 cu. in.. Do you have any idea how many ways that engine can be built using ONLY factory Chevy parts?.. (1) bore a 283 block to 4 inches.. (2) put a 283 crank in an early 327 block. (3) use a factory built 302 engine. (4) put that same 302 crank in a 350 block, just to name a few, but there are more.. And to top it off, none of the "factory stamped numbers" mean a damn thing in each of those examples.. Those numbers only tell what the block started out as.

Just for the record, I didn't revive this thread, someone else did that......

[jumpsoffrock]

Originally Posted by RustyPile

True about the age of the post, but be honest with yourself -- you have not the slightest idea what he meant, only what he said. What I stated here was also correct ten years ago and is still correct today. None of that alleviates the fact that the post was incorrect. This is a prime example of how false and untrue information gets spread over the internet.

I started building race engines around 1962.. The favorite sbc for some of the racers in those days was a Chevy 301 cu. in.. Do you have any idea how many ways that engine can be built using ONLY factory Chevy parts?.. (1) bore a 283 block to 4 inches.. (2) put a 283 crank in an early 327 block. (3) use a factory built 302 engine. (4) put that same 302 crank in a 350 block, just to name a few, but there are more.. And to top it off, none of the "factory stamped numbers" mean a damn thing in each of those examples.. Those numbers only tell what the block started out as.

Just for the record, I didn't revive this thread, someone else did that......

Rusty, your original correction post was helpful and I appreciate it.
But Marks reply to you didn't seem to have much aggression. Yes he pointed out you replied to an old post, but basically none of his verbiage came off like he was "setting you strait".

But your reply that I have quoted comes off a bit on the offensive.
Mark never accused you of reviving anything.

Again, you are definitely correct about the spread of misinformation. Thanks for the specifics you gave.

[geezer#99]

Originally Posted by landy

Since the same block is used for the 307 and 350 (and for many other small blocks as well), I don't think you can tell just be looking at them.

Isn’t that the truth!
100% of the people (that includes crusty pile) who pop the hood to look at a small block can’t with any degree of accuracy tell the cubic inches let alone the bore stroke or journal size.

[truckster]

Originally Posted by geezer#99

Isn’t that the truth!
100% of the people (that includes crusty pile) who pop the hood to look at a small block can’t with any degree of accuracy tell the cubic inches let alone the bore stroke or journal size.

I was suckered once. Being young and honest, I believed other people were honest too. I ended up buying a SBC, without checking any numbers, that was supposed to be a 350 but turned out to be a 262.

And the bickering is silly.

[RustyPile]

Originally Posted by jumpsoffrock

Rusty, your original correction post was helpful and I appreciate it.
But Marks reply to you didn't seem to have much aggression. Yes he pointed out you replied to an old post, but basically none of his verbiage came off like he was "setting you strait".

But your reply that I have quoted comes off a bit on the offensive.
Mark never accused you of reviving anything.

Again, you are definitely correct about the spread of misinformation. Thanks for the specifics you gave.

I make no apologies for correcting erroneous information. Speaking of being offensive. I took offense at Mark telling me what Landy meant some 10 years ago. Landy said, "the same block is used for the 307 and 350 (and for many other small blocks as well)".. They are not the same, they only look the same..

And the tone I used got your attention.. It will also get the attention of any future readers of this thread.. For the most part, the information given on these forums is accurate, but some people post simply to see their name "in the lights", damn the accuracy of what they say.. This really screws it for the ones who are searching for answers to their questions.