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350 with small journal's???

 
67Delmont
I love my Chevy Chevette!
Posts: 18
Joined: 03/13
Posted: 03/18/13 02:35 PM

Me and one of my friends got in arguement last night. He allowed his 350 was a small journal. I have never heard of one. First one was made in 68 everything went medium journal that year. He said his friend run #'s and it came back small journal 327/350. Anybody else ever heard of this?  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 03/18/13 04:48 PM

there were small journal 283 and 327 and 302 motors as i recall off the top of my head.. these have 2.0" rod journals..

there were what is actually the medium journal 350, 307 and 327 motors... known to most as large journal... these have 2.1" rod journals

then came the 400 with the even larger main journals..  but 2.1" rod journals.


want to have some fun.. you will once in a while find a 350 block...  with a 400 crank by checking the casting numbers.. but the mains were turned down from the 400 size to the 350 size mains...  but they also turned the rod journals down to 2.0" and the small journal 5.7 rods were used..  with 11/32" rod bolts.  instead of the 3/8 rod bolts..  this is an old school 383...

one time.. the boss at the engine rebuilder bought a core engine.. a 4 bolt main 350 that was only 30 over.. we sold a lot of those and the bores were clean.. so we could probably hone it to 040 over..  it had main bearing spacers and a small journal 327 crank..  6" H beam rods and 350 pistons or really close to them... my boss who has run his fathers engine rebuilding shop for many years.. swore up and down that chevy never made a 6 inch rod.. i kept trying to get across that these were not gm rods they were aftermarket race rods..   there was no name on them.. he told the tear down guys to throw them out..  i grabbed them and shoved them in a used piston box.. but somebody nabbed them.. probably the bosses son.. who had his eye on them also..  i quit soon after..  

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68scott385
I mow my lawn and find Chevys
Posts: 1994
Joined: 10/09
Posted: 03/18/13 04:55 PM

...some men you just can't reach...  
68scott385 68scott385 68scott385

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/18/13 04:56 PM

67Delmont

The Small Block Chevy Cranks are labled as such: Small Journal, Medium Journal, and Large Journal which is really the 400 Crank only.

There was only a medium journal 350 crank. 2 piece rear main oil seals.

There were 327 small journal, and 327 medium journal cranks. 2 piece rear main oil seals.

If you need the journal sizes let me know?

I hope this answered any questions you may have. The fore mentioned cranks are 2 piece rear main oil seals only.

There are 1 piece rear main oil seals but we won't get into them.... Confused

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/18/13 05:08 PM

67Delmont
"SMALL JOURNAL CRANKS"

Let me clarify the journal sizes for you.

Crank Strokes with small journals(2.30" mains/2.00" Rods) include the 3.00" strokes on Gen.1 265, 283, and the 1967 302 Z-28 engines.

The 3.25" stroke lengthswere used on 327s from 1962 thru '67 with small journals. The 5.7" length rods with small journals, and 11/32" rod bolts were used with these cranks.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/18/13 05:25 PM

"MEDIUM JOURNAL SIZED CRANKS"

Strokes with medium sized journals: (2.45" mains/2.10" rods) include 1968 to '69 Z-28 with a 3.00" stroke, a 3.10" stroke on the 262, 3.25" used on the 307, and the '68 327s, and 3.48" strokes on these were 267, 305, and the 350. The Gen.II 265 CI V-8 uses these journal sizes with a 3.00" stroke with a one piece rear main oil seal. The 5.7" length rods with a 2.10" rod journal cranks with the exception of of the Gen.II 265 L99 engine, which uses  a 5.940" length rod. Production rods for medium sized journals have a 3/8" rod bolt.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/18/13 05:33 PM

"THE LARGE JOURNAL SIZED CRANKS"

The 400 used a 3.75" stroke with larger main journal diameters of 2.65" and rod journal of 2.10". The 400 uses a shorter 5.565" length rod with 3/8" rod bolts.

The 400 rod bolt has a unique head on the bolt, which helped provide more clearance between the  bolt head and the cam lobes, and  the block itself.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/18/13 05:35 PM

If anyone needs the materials the cranks are made of, part numbers, or any information on small and some big block cranks let me know. Maybe I have the info you need.

Bob  

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pepsi1
I mow my lawn and find Chevys
Posts: 1718
Joined: 09/11
Posted: 03/19/13 05:38 AM

Back in the day we cut large journal cranks down to small journal bearing sizes. We did this mainly to use Small Journal Aluminum Rods. It gave us the beef where it was needed and it helped bearing speeds.
  A point of interest: A forged production GM 350 crank is only case hardened. If any more then .010 is machined from the crank journals, the crank should be rehardened on those journals. They can be polished without hurting the surface area.
  Also back in the day some guys went through the expense of having the crank journals machined and then the journals where chrome plated.
  With todays hardening processes crank journals can be made too hard, and they become brittle. Sometime at a NHRA national meets, top fuel or funny car guys will sell broken parts. Look at cranks especially and see how they actually break.

Bob  

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waynep71222
I have an SS396 tatoo
Posts: 448
Joined: 03/12
Posted: 03/19/13 08:39 AM

A point of interest: A forged production GM 350 crank is only case hardened. If any more then .010 is machined from the crank journals, the crank should be rehardened on those journals. They can be polished without hurting the surface area.


wow.. thats some info i was never aware of...  that explains why a lot of people won't accept more than a 10/10 crank..   i always got deals on 30/30 cranks . i did not care.. as they were going in my projects.. and i never pushed them that hard..  although the SJ327 i had in the 67 camaro really got wound tight..  but that was actually a 10/10 crank..  5:38 gears will do that at 130 mph trap speeds..  

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busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/09/13 10:50 PM

I have a old friend, his dad was working in the Chevy factories when this was going on. He swears to me that there was about 300 - 400 sbc small journal 350s made. he said it was a test of the journal size. He was not sure how many made it to the street, but said that about 2/3 were used as mules for testing. This could be one of those test mules that made it to the street.  

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busterrm2013
V-6 Camaros rule!
Posts: 46
Joined: 07/13
Posted: 07/09/13 10:50 PM

I have a old friend, his dad was working in the Chevy factories when this was going on. He swears to me that there was about 300 - 400 sbc small journal 350s made. he said it was a test of the journal size. He was not sure how many made it to the street, but said that about 2/3 were used as mules for testing. This could be one of those test mules that made it to the street.  

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