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  #1  
Old Feb 4th, 09, 7:45 PM
real reddog real reddog is offline
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Steve
 
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Default 327 small journal vs large journal?

Whats the difference and which is better or are both just as good as the other? Is the large journal stronger? Does the small journal twist up quicker? Just wondering what the pros and cons are.
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  #2  
Old Feb 4th, 09, 7:56 PM
trmnatr trmnatr is offline
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Default Re: 327 small journal vs large journal?

Quote:
Originally Posted by real reddog View Post
Whats the difference and which is better or are both just as good as the other? Is the large journal stronger? Does the small journal twist up quicker? Just wondering what the pros and cons are.
For a street engine or street/strip engine i would go with the large journal for a few reasons,,,,
- cheaper rods
- blocks more available (350 block)

In a high RPM 327 i would want the small journal, small rod journal cranks i prefer. The bearings look better in them usually. I like smaller rod journals.

I like to use 350 blocks and a crank that is 350 main sized with small rod journals

So bottom line as you can see there is almost no difference.

You know how they have bearing spacers to use a 350 main crank in a 400 block ? They also have main bearing spacers to use a small journal main crank in a 350 block and you just use small journal rods. Alot of super stockers do this

You get the bearing spacers from Race Engineering
http://www.raceeng.com/p-7689-bearin...27-to-350.aspx
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  #3  
Old Feb 4th, 09, 8:07 PM
pdq67 pdq67 is offline
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Default Re: 327 small journal vs large journal?

What Butch said!

And remember that guys are rpm'ing SB 350+ engine cranks up above 9,000 rpm that have been cut to Honda rod journal size fine!

GM and aftermarket SB designed cranks are that tough!!

pdq67
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  #4  
Old Feb 4th, 09, 8:50 PM
1989GTA 1989GTA is offline
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Default Re: 327 small journal vs large journal?

...and they make rod bearings with spacer for using a 2.100" rod on a 2.00" rod journal. Lots of 350 main bearing crankshafts with a 2.00" rod journals available. I guess it is worth a couple of extra horsepower.

Last edited by 1989GTA; Feb 4th, 09 at 9:41 PM.
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  #5  
Old Feb 4th, 09, 9:08 PM
trmnatr trmnatr is offline
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Default Re: 327 small journal vs large journal?

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Originally Posted by 1989GTA View Post
...and they make rod bearings with spacer for using a 2.100" rod on a 2.00" rod journal. Lots of 350 main bearing crankshafts with a 2.00" rod journal available. I guess it is worth a couple of extra horsepower.
Yes, race engineering has the rod bearings that go into a large journal rod and allow them to work on a small journal crank

Also, federal mogul used to have main bearings to go into a 350 block that would allow you to use a small journal main crank, i no longer know of anybody offering these

Actually, myself and a machine shop tried to find a set with no luck
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  #6  
Old Feb 4th, 09, 9:40 PM
1989GTA 1989GTA is offline
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Allen
 
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Default Re: 327 small journal vs large journal?

Lunati, King Bearing and announced by Clevite late last year that I'm aware of. Must be some demand for the rod spacer bearings.
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  #7  
Old Feb 4th, 09, 9:49 PM
trmnatr trmnatr is offline
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Default Re: 327 small journal vs large journal?

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Originally Posted by 1989GTA View Post
Lunati, King Bearing and announced by Clevite late last year that I'm aware of. Must be some demand for the rod spacer bearings.
interesting

Probally because small journal rods are so heavy

If your building a street car with 5.7" eagle h-beam rods the weights are a good difference, the weight are as follows
5.7" h-beam large journal 630grams
5.7" h-beam small journal 670grams

I dont recall the spacer bearings being 40grams heavier !!!!!
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  #8  
Old Feb 4th, 09, 10:38 PM
1989GTA 1989GTA is offline
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Default Re: 327 small journal vs large journal?

That makes a lot of sense to me. Probably not to much difference in the weight of the bearings.
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  #9  
Old Feb 5th, 09, 12:22 AM
Wolfplace Wolfplace is offline
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Default Re: 327 small journal vs large journal?

Quote:
Originally Posted by trmnatr View Post
interesting

Probally because small journal rods are so heavy

If your building a street car with 5.7" eagle h-beam rods the weights are a good difference, the weight are as follows
5.7" h-beam large journal 630grams
5.7" h-beam small journal 670grams

I dont recall the spacer bearings being 40grams heavier !!!!!
=
That is because the forgings are the same and if you put a thick bearing in the rod you will be right back where you started weight wise

A dedicated 2" rod of the same design will be lighter
Look at the Oliver or Compstar line
6" Compstar rods
2.1" rod 612
2" rod 591
1.88" rod 522
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  #10  
Old Feb 5th, 09, 10:03 AM
Bryan Maloof Bryan Maloof is offline
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Default Re: 327 small journal vs large journal?

Remember too, not very many large journal 327 steel cranks around. They only came in 68 1/2 trucks. I have one left from many years ago, but they are not near as strong as the small journal crank. The small journal 327 crank is the heaviest/strongest SB crank GM has ever made in a production engine.
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  #11  
Old Feb 5th, 09, 6:20 PM
1989GTA 1989GTA is offline
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Allen
 
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Default Re: 327 small journal vs large journal?

I had a chance to weigh the bearings for the 2.1" rods. One set for the 2.100" journal and the other set for the 2.000" journal. The ones for the 2.100" journal weigh 46 grams. The ones for the 2.000" journal weigh 74 grams. 28 gram difference.

Looking at the rods from Compstar that were posted there is a 21 gram difference. I guess one would have to weigh the bearings for dedicated 2.0" rod to see the real difference. But anyways the bearings are available and certainly doable.
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  #12  
Old Feb 5th, 09, 6:53 PM
daveseitz daveseitz is offline
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Default Re: 327 small journal vs large journal?

Nascar runs the small bearings in their engines as it does cause less friction at higher RPM.
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  #13  
Old Feb 5th, 09, 8:04 PM
pdq67 pdq67 is offline
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Default Re: 327 small journal vs large journal?

Right,

"The small journal 327 crank is the heaviest/strongest SB crank GM has ever made in a production engine. ", but it's the large journal 283 crank that has the most journal overlap.

pdq67
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  #14  
Old Feb 5th, 09, 10:50 PM
Bryan Maloof Bryan Maloof is offline
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Default Re: 327 small journal vs large journal?

Quote:
Originally Posted by pdq67 View Post
Right,

"The small journal 327 crank is the heaviest/strongest SB crank GM has ever made in a production engine. ", but it's the large journal 283 crank that has the most journal overlap.

pdq67
Does that mean it is the strongest though??? The DZ 302 crank is a good crank, but just not as strong as the 327 SJ
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  #15  
Old Feb 5th, 09, 11:04 PM
trmnatr trmnatr is offline
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Default Re: 327 small journal vs large journal?

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Originally Posted by Bryan Maloof View Post
Does that mean it is the strongest though??? The DZ 302 crank is a good crank, but just not as strong as the 327 SJ
327 small journal crank will hold 600-650hp @ 9,000rpm with 330-430gram pistons with the heavier pistons using aluminum rods

Many Super Stock engines going 9,000rpm and many high compression MP Engines

However, i have turned large journal steel cranks up to 8,500rpm at the track, well actually i have turned them much higher but that was when it spun and the reb limiter failed, oh
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