C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

85 Engine

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Old Jul 18, 2005 | 09:49 PM
  #1  
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Default 85 Engine

I know this may sound like a dumb question but will ask it anyway. Am thinking of replacing my worn out motor in my 85, is there anything special about this motor or can I replace it with any 350 engine and just use my intake and accesseries.
Any info would sure help.
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Old Jul 18, 2005 | 09:53 PM
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Just a basic 2-piece rear 350.

Replace with whatever you want.
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Old Jul 18, 2005 | 10:28 PM
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What Vader said....

Of course, you could always think of this as an opportunity to turn things up a notch....

GM offers some excellent crate motors, bolt in affair.
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Old Jul 18, 2005 | 10:56 PM
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Originally Posted by selkirk24
I know this may sound like a dumb question but will ask it anyway. Am thinking of replacing my worn out motor in my 85, is there anything special about this motor or can I replace it with any 350 engine and just use my intake and accesseries.
Any info would sure help.

There is something special about the 85 motor. The pistons and crankshaft are forged. I just had mine overbored .03" and installed new TRW forged pistons. I also had the crank turned.
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Old Jul 18, 2005 | 11:50 PM
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Originally Posted by Bluevette85
There is something special about the 85 motor. The pistons and crankshaft are forged. I just had mine overbored .03" and installed new TRW forged pistons. I also had the crank turned.
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Old Jul 19, 2005 | 03:02 AM
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Two part issue.

1. Yeah it has some unique Corvette components.

2. However, you can drop a GM crate motor in and use your intake and everything else just bolts on normally.

If you don't plan on big HP mods and arn't into nitro and drag racing the crate engine is a good cheap way to go.

I did it and it runs fine in my 85 daily driver. Paid about $1300 for the long block from a Chevy dealer and it came with a factory warranty.
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Old Jul 19, 2005 | 08:09 AM
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Would another possibility be to put a good set of heads on the '85 engine?

Or would the internals need to be changed out with the new heads?
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Old Jul 19, 2005 | 10:37 AM
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Originally Posted by Bluevette85
There is something special about the 85 motor. The pistons and crankshaft are forged.
Right on the pistons. Wrong on the crank.

A one piece seal engine can replace yours, with the addition of the flywheel or flexplate for a one piece seal engine. So basically, the answer to the question, is yes.

mikey whipreck,
Heads can be swapped into the '85 short block with little or no other changes, but it won't do much for a "worn out motor ".

RACE ON!!!
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Old Jul 19, 2005 | 12:41 PM
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Originally Posted by CFI-EFI
Right on the pistons. Wrong on the crank.

RACE ON!!!

My stock 85 crank was forged. It rang like a bell when hit with a hammer.
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Old Jul 19, 2005 | 01:11 PM
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85 has forged pistons and crank. The '84 & '85 motors were build with parts that can eaisly handle the power they were putting out.

I'de rebuild the motor, if not somebody who knows their motors will pick it up from you quite quickly
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Old Jul 19, 2005 | 01:25 PM
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Originally Posted by Bluevette85
My stock 85 crank was forged. It rang like a bell when hit with a hammer.
Ditto.... Mine too .. both were and are forged..
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Old Jul 19, 2005 | 03:29 PM
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Bluevette85, bigcityvette, MrNuke,
Interesting! I wonder what happened. I have never seen any more of my crankshaft than what extends forward of the front main bearing. My 1984-89 Corvette Y Parts and Illustration Catalog, "group 0.646, Crankshaft, engine", says, "84-85 Y (5.7-8).....3932444". My Corvette 1984 Specifications manual, states, "Engine: Crankshaft: Material: Nodular cast iron." I Googled "3932444" and ended up here:
http://www.google.com/search?q=39324...e=off&filter=0

I don't know if that URL will endure, or not. some of the listings on that page definitely list the 3932444 as a cast crank.

At this first link, the crankshaft is addressed in the 4th paragraph of the second post. http://www.thirdgen.org/techbb2/show...hreadid=278538

At this next link, under "detailed description", the crankshaft is described in the 12th and 13 line. http://69.20.110.81/index.asp?PageAc...D&ProdID=24755

There are more links verifyung that the part number is a cast crank. It is hard to doubt three knowledgeable posters, but I wonder where the break down is? Is my parts book wrong? The description of the part number holds up in too many places for that to be wrong. Did Chevy run out of cast cranks???

RACE ON!!!
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Old Jul 19, 2005 | 11:13 PM
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My '85 had forged pistons but a cast crank. A cast crank will ring also. It was also a 2-bolt block.
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Old Jul 19, 2005 | 11:27 PM
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Originally Posted by danno85
My '85 had forged pistons but a cast crank. A cast crank will ring also. It was also a 2-bolt block.
I have 4 or 5 cast 350 one pc seal cranks floating around. For some reason they seem to ring like a bell. I kept them thinking they were forged. The casting number and thin parting line tell me all of mine are cast.
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Old Jul 20, 2005 | 01:20 PM
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Originally Posted by danno85
My '85 had forged pistons but a cast crank. A cast crank will ring also. It was also a 2-bolt block.
Originally Posted by Pete K
I have 4 or 5 cast 350 one pc seal cranks floating around. For some reason they seem to ring like a bell. I kept them thinking they were forged. The casting number and thin parting line tell me all of mine are cast.
The 3932444 crank that belongs in the 1984 and 1985 Corvettes, certainly is spec'd to be cast.

RACE ON!!!
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