Need help with L71 L89 engine internals
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,962
Likes: 579
From: Pittsburgh PA
Need help with L71 L89 engine internals
Here's my question- what crankshaft and connecting rods would a 68 L89 have?
Crankshaft seems to be either the "6223" crank or "7115"
Connecting rods-
3/8 dimple or 7/16 dimple?
My research shows it would be the 6223 crankshaft but I really can't get a solid answer on the rods?
Crankshaft seems to be either the "6223" crank or "7115"
Connecting rods-
3/8 dimple or 7/16 dimple?
My research shows it would be the 6223 crankshaft but I really can't get a solid answer on the rods?
Team Owner
Joined: Mar 2002
Posts: 44,677
Likes: 1,830
From: Huntsville AL
L89 is a L71 427, 435hp engine with aluminum heads. So what your looking for is L71 specs.
I need to go dig a book out but I'm thinking its the 7115 and 7/16 rods
Corvette by the Numbers 1955 - 82
The 7115 crankshaft 65-69 / 427 / Forged Steel / 3.76 Stroke
The 6332 crankshaft 70-72 / 402 / Forged Steel / 3.76 Stroke
All Hi-Performance 427 Big Blocks 66-69 had the second design 3/8" rod bolts with double dimple.
The third design rod with 7/16" rod bolts were for the 69 L88 & ZL1 options.
For what its worth I have the 6332 crankshaft in my 427 390 hp, great crankshaft.
I need to go dig a book out but I'm thinking its the 7115 and 7/16 rods
Corvette by the Numbers 1955 - 82
The 7115 crankshaft 65-69 / 427 / Forged Steel / 3.76 Stroke
The 6332 crankshaft 70-72 / 402 / Forged Steel / 3.76 Stroke
All Hi-Performance 427 Big Blocks 66-69 had the second design 3/8" rod bolts with double dimple.
The third design rod with 7/16" rod bolts were for the 69 L88 & ZL1 options.
For what its worth I have the 6332 crankshaft in my 427 390 hp, great crankshaft.
Last edited by Mr D.; Feb 12, 2017 at 05:04 PM.
Thread Starter
Drifting
Joined: Nov 2016
Posts: 1,962
Likes: 579
From: Pittsburgh PA
bumping this back up hoping for some more input
here's my issue:
I made a thread about buying a 427 L89 engine a bit ago. That block came with the following parts:
1- 6223 crankshaft
2- 8 3/8 dimple rods
3- 5 7/16 dimple rods
the guy(who died 25 years ago) that owned all of this was into building and racing engines, so just because parts came with the block is no guarantee thats whats came out of it.
the more I google, the more conflicting info I find.
the 6223 and the 7115 crankshafts seem to almost be interchangeable number (search enough and there are ppl pulling 6223 cranks out of 7115 boxes) so I'm not real concerned and will use the crank I have.
my main concern is what rods were originally be in the motor. i continue to find conflicting info on this. some sites say the 7/16 rods were only l-88, others say they were use on any 427.
is there anyone on the board who has actually torn down there L71/L89 and can say what was inside it?
here's my issue:
I made a thread about buying a 427 L89 engine a bit ago. That block came with the following parts:
1- 6223 crankshaft
2- 8 3/8 dimple rods
3- 5 7/16 dimple rods
the guy(who died 25 years ago) that owned all of this was into building and racing engines, so just because parts came with the block is no guarantee thats whats came out of it.
the more I google, the more conflicting info I find.
the 6223 and the 7115 crankshafts seem to almost be interchangeable number (search enough and there are ppl pulling 6223 cranks out of 7115 boxes) so I'm not real concerned and will use the crank I have.
my main concern is what rods were originally be in the motor. i continue to find conflicting info on this. some sites say the 7/16 rods were only l-88, others say they were use on any 427.
is there anyone on the board who has actually torn down there L71/L89 and can say what was inside it?
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
if you look at the Chevrolet Corvette Parts and Illustration Catalog Group 0.603, ROD, Engine Piston you will find the L88 did not use the same part number for the rod as the L71/L89 in 1968
The term HD is the L88
The term SP. H/PER is the L71/L89
68 Y(427) W/HD (1st Design) 3909846 Rod (Pink) (3/8 Bolt)
68 Y(427) W/HD (2nd Design) 3969804 Rod (7/16 Bolt)
65-69 Y (396,427) W/SP. H/PER 3856240 Rod (Ident Rib on Conn Rod Cap) (Blue)
The term HD is the L88
The term SP. H/PER is the L71/L89
68 Y(427) W/HD (1st Design) 3909846 Rod (Pink) (3/8 Bolt)
68 Y(427) W/HD (2nd Design) 3969804 Rod (7/16 Bolt)
65-69 Y (396,427) W/SP. H/PER 3856240 Rod (Ident Rib on Conn Rod Cap) (Blue)
Last edited by MelWff; Feb 18, 2017 at 11:54 AM.
Le Mans Master
Joined: Apr 2001
Posts: 9,556
Likes: 288
From: Granbury Texas
Depends what your "usage" will be. NCRS never looks at engine internals, therefore you should (and I would) use the "BEST" internals available, regardless of part number.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
if you look at the Chevrolet Corvette Parts and Illustration Catalog Group 0.603, ROD, Engine Piston you will find the L88 did not use the same part number for the rod as the L71/L89 in 1968
The term HD is the L88
The term SP. H/PER is the L71/L89
68 Y(427) W/HD (1st Design) 3909846 Rod (Pink) (3/8 Bolt)
68 Y(427) W/HD (2nd Design) 3969804 Rod (7/16 Bolt)
65-69 Y (396,427) W/SP. H/PER 3856240 Rod (Ident Rib on Conn Rod Cap) (Blue)
The term HD is the L88
The term SP. H/PER is the L71/L89
68 Y(427) W/HD (1st Design) 3909846 Rod (Pink) (3/8 Bolt)
68 Y(427) W/HD (2nd Design) 3969804 Rod (7/16 Bolt)
65-69 Y (396,427) W/SP. H/PER 3856240 Rod (Ident Rib on Conn Rod Cap) (Blue)
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Team Owner
Joined: Mar 2002
Posts: 44,677
Likes: 1,830
From: Huntsville AL
Found this;
969804 - 1969 Zl-1 L88 Forged Connecting Rod Assembly - NOS GM
This NOS GM heavy duty ZL-1 L88 Forged Connecting Rod, GM part number 3969804 is finished for floating wrist pins. It is manufactured from 4340 steel, magnaflux inspected and shot peened. Included is super quality 7/16" boron steel bolts. This rod is color coded green. This is a NOS (new old stock) item that is limited to quantity on hand. Once they are gone, they are gone forever. Get them while you can.
969804 - 1969 Zl-1 L88 Forged Connecting Rod Assembly - NOS GM
This NOS GM heavy duty ZL-1 L88 Forged Connecting Rod, GM part number 3969804 is finished for floating wrist pins. It is manufactured from 4340 steel, magnaflux inspected and shot peened. Included is super quality 7/16" boron steel bolts. This rod is color coded green. This is a NOS (new old stock) item that is limited to quantity on hand. Once they are gone, they are gone forever. Get them while you can.