What are the pros and cons of the 327 w/ a small journal and the 327 w/ a large journal?

 

Pros: Great mechanical compromise in stroke versus bore because the rod length can be nearly optimized without severly restricting piston design.

Cons: Displacement (If you plan on making more torque).

 

Small journal
Pro: A little less weight spinning around at 7000 rpm.
Con: Finding small journal con rods.

Large journal
Pro: more metal = more strength. Standard SBC con rods are everywhere.
Cons: A little more weight spinning around.

There are very few small journal SBC engines built up any more. Only exotic combinations with offset grinds.

 

Thanks alot guys. You guys sure helped me a bunch.
Also which crank would be a great choice for the 327 if I plan to build the motor for very high performance and Street/Strip racing? The small or large journal? I would go with the large b/c if i throw rods the standard SB Chevy rods are everywhere and readly available.
I just have a 68' 327 block from a 68'Chevelle currently and wanna build it up. I can't find and factory specs on the engine such as bore & stroke and rod size as well as the torque specs, ect.

 

SJ cranks are all forged, LJs are mostly cast

 

Crank journal sizes http://www.mortec.com/journal.htm Mains 2.45", rods 2.10".

Bore & stroke http://www.mortec.com/borstrok.htm Bore 4.000", stroke 3.25".

Your '68 block is the same as a 2-bolt 350 block.

By "torque specs", do you mean bolt tightening specs? If so, any standard repair manual that covers SBCs would have them.

By 1968, the 327 was a base V8, non-performance 2-bbl engine. Step #1 in a build-up is to throw away the heads. Don't try to work them over, warm them up, etc. - don't waste any time or money on them. Step #2 is to do the same with the intake. After that, it's standard SBC build-up stuff.

 

Don't forget that small journal cranks also have a lower bearing speed. This results in less friction (more HP) and better bearing life. For a street engine its not worth concerning yourself with. In a high RPM race engine it can make a difference.

 

I think this is the main concern that's overlooked. There is a degree of gain in low speed torque with every increase in stroke; but there is not however a linear increase in output, power per inch, as the stroke goes up. That's why 400's work so well on the street and you'll find that the 327's work real well on the track.

 

Step #1 in a build-up is to throw away the heads. Don't try to work them over, warm them up, etc. - don't waste any time or money on them.

NOT-ALWAYS-IF-YOU-HAVE-THE-HEADS-SEE-IF-THEY-HAVE-DOUBLE-HUMPS-ON-THEM-THEY-WILL-ALSO-HAVE-THE-NUMBERS-461-ON-THEM-GIVE-THEM-A-POCKET-PORT-JOB-AND-THEY-WILL-FLOW-JUST-AS-MUCH-IF-NOT-MORE-THAN-THE-NEW-VORTECHS-I-HAVE-THEM-ON-MY-350-AND-I-SHOULD-BE-PUSHIN-ABOUT-360-HP

 

Hey smoky21 what are "double humps"? I have power pack heads for my 327 and I was gonna put aluminum Vortec heads on this motor. Also what's UP with the dashes after every word and why is it in all caps?

 

Could it be possible to destroke a 350 to a 327?

Can a 350 crank be fit into a 327?

If I over bored a 327 0.60 will it be more powrful and quicker?

 

Its possible to destroke a 350 to a 327...just use a large journal 327 crank.

A 350 crank will go in a large journal 327 block, creating a 350.

I wouldn't bore any block more than necessary to get good ring seal. Most 327s can go .060, though I wouldn't reccomend it unless you have to.

Some 327s had good heads (461s, 462s, etc), but few had accessory bolt holes, so you can't run late model accessories.

 

look-in-the-post-smoky21-if-you-want-to-see-what-they-look-like-just-go-to-ebay-and-do-a-search-for-them.-theyre-nothing-like-a-dart-but-they-are-a-lot-better-than-most-3rd-gen-heads

 

Hey Smoky21, I already checked out that post titled smoky21, b/c I was a dummy for accidently posting it. I was trying to reply to this tread. Thanks for the input guys.

 

Hey guys nevermind the destroking a 350 part as it will not work anyways.

 

If-you-still-wanna-destroke-that-350-you-can-just-go-get-a-285-crank-have-it-machined-a-little-and-you'll-have-a-nice-302

 

How will it not worK? The blocks are the same: the only difference between them is the stroke. Granted, you can't put a small journal 327 crank in a 350, but a large journal one will give you a 327. I wouldn't do it, but it could be done very easily.

 

smokey you can't change the stroke by machining the crank, unless you know a neat trick i don't. the stroke is measured from the CL of the main to the CL of the pin. no matter how much metal is removed the CL to CL measurement will stay the same.

 

I-was-referring-to-having-it-balanced-and-magnafluxed

 

Called offset grinding. Available at most race shops. Common to increase stroke by 0.015" during grinding. As I recall this is the max allowed in SS classes. However you are limited to whatever metal is there. If you grind it down 0.010" you can take this almost entirely off one side increasing stroke by about 0.015". You should remember all the discussions a couple of years ago about offset grinding a 400 crank for small journal rods to get about 415CI.

 

Here's a set of double-hump heads from the outside. Note that this set, unlike the 461 casting mentioned earlier, has accessory bolt holes, so they will actually install into one of these cars without any .... ummmm, alternate engineering schemes ..... required.

 

And the other end...

Don't let anyone with old heads tell you differently, these are The Heads to have if you want a junkyard performance motor. There are none that are "almost as good". The version with bolt holes also has a modified combustion chamber compared to the older ones without the holes, so they will actually almost run on modern gasoline if matched correctly with the rest of the engine.

 

oooops

 

yeah DR i thought of that when i was typing that reply and figure it didn't apply to waht he was refering to, i damn near went back and editied it but never. also you could build up the pin and move the CL anywhere you wanted, but again i didn'tthink it really applied to what he was refering.