327 crank

I'm going to build a 348 (destroked 400) for my 70 nova project. I know why not biuld a 400? Well the car is an ex-modified production racer from the early 70's and a 348 was hot motor for the wieght per cubic inch class. I heard that all the large journal 327's had forged cranks, is that true? I do have access to a number of these motors and 2 or 3 are 275 hp motors. I hope they are cuz i'm getting impatient and want to hear 348ci at 8500rpm as soon as possible.  

You should be able to easily find a forged 327 stroke crankshaft, remember wide casting lines are steel cranks, narrow parting lines are cast cranks. Remember 8500 RPM's is nothing to joke at, the rest of the engine and driveline better be up to snuff to take it.

Give it up for a short stroke!!!!!

I love em dude...theres nothing better...forget that "no replacement for displacment" stuff

Build a short stroke motor right and itll beat em everytime..

Stick a good long rod in there too....are you gonna use spacer bearings or do you have a different block?

-Shred

I know all the small journal 327's had forged cranks, but I don't know about the large journals.  

yea i'm gonna use one of comp cams spacer bearings, i dont see any problem with running one, its only a extra thick bearing,who knows it might be better.

And the short stroke motors are definitly fun to drive. The 350 that was in the car when i first bought it sounding like it was busting ass at 4500 rpm. I have a small journal 302 (310 actually) in it now and it will cruz at 4500 all day long with out even sounding stressed one bit. and theres nothing like going 8000 with open headers on the street.

how come no-one else build short stroke motors? After all the thing that made SBC's so great in the first place was the ability to rev really hard.

That's a completely incorrect statement.  

being that the car is an old MP car, it has a 12 bolt with 4.88's, 33-spline axlesand a new detroit locker (had 5.14's when i bought it). and i believ back in the day it used a doug nash 5 spd. or a hemi box. it is currently running a G-Force 4 spd. I wanted the driveline and suspension to be ready before I actually built the motor. So far it shrugs off the 7500rpm launches i've givin it with my 310ci.

yeah ok....so I guess its just personal preferance...
Some might say that is incorrect too...but thats fine

I just like the torque curves of short stroke engines.
Its easier to hook em up, and they like the top end.
Theres just somthing about a screamer that I like...

I WANT A 302!!!...GIMME ONE!!
but...pistons are too expensive...darn

-Shred

Is this what you have in mind?

http://purplesagetradingpost.com/sumner/techinfo/350%20chevy%20engine.html

yea, It was a popular motor in Modified Production way back when. My car was built run MP in 1971, and from what i have been told by the original owner it started the 71 season with a killer 288ci small block. I believe it was then upped to a 302ci. I'll try to post some of the old  race pics of the car launching. If i had to guess, i'd say he was side stepping the cluth at about 10-11,000rpm's. Crazy!

If I remember Chevy only built the large journal 327 for 1 year (1967) and it was forged... later 307 motors used the large journal cast crank.
Can't wait to see those photos.. in 1970 I built motor mounts for a freind to put a 302 with tunnel ram into a 1960 Ford Falcon, he used to drop the hammer at 8500 RPM, once he gave me a ride and he missed 2nd gear and with no rev limiter it went way in excess of 10K rpm, the valves floated and puked gas all over the windshield, I looked at the tach which was a 10K unit and it was pegged so I don't know how high it went... But, it didn't blow up!

1967 was the last year for the small journal 327, and the only year for the small journal 302.  In 1968, both the 302 and 327 converted to the larger journal cranks.

* Many rodders prefer(ed) the small journal 327 cranks due to less rotational surface area - thus, lower bearing speed.

Okay, let me get this correct..All the 1962 thru 1967 327 cranks were small journal and 1968 and 1969 were the only two years for large journal 327 cranks and 1968 was the only year for the large journal steel crank.
The large journal steel cranks were only used in 1968 Corvettes and GM trucks.
Right?  

"Okay, let me get this correct..All the 1962 thru 1967 327 cranks were small journal and 1968 and 1969 were the only two years for large journal 327 cranks and 1968 was the only year for the large journal steel crank.
The large journal steel cranks were only used in 1968 Corvettes and GM trucks.
Right?"

Yes, all pre-1968 cranks/blocks were small journal. 

Were '68 large journal steel cranks only used in 'Vettes and trucks?  I don't know, and wouldn't bet bank on it.  Too much funny stuff rolled off the assembly lines back then.  It's possible that forged assemblies made their way into sedans, etc. during that era and vice versa.  Cast and forged cranks were offered in both small and large journal measurements.

As someone else pointed out, one way to tell a cast crank from a forged one is to simply look at the 'parting line' on the front journal arm.  A very thin 'parting line' indicates a cast crank, while a wide 'parting line' (~1/4") is a forged crank.  

You are RIGHT ON about funny stuff getting out back then.. a friend of mine bought a new 454 and when we pulled the oil pan I found that the block was drilled and tapped for 4-bolt mains yet it had 2-bolt mains installed! I had never seen this before yet someone else told me they had. Also, I bought (and still have) a 454 with 2-bolt mains with a forged crank part number 7115 I check it out and found it was forged, nitrided and cross-drilled crank. I know that they would sometimes just use whatever they had to make the orders and refill stock later.
Those were sure great times tho!

Edited 2/19/2006 1:06 am by Wulff406