Difference between 84-85 engine and 86-87??

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wb_7354

Active Member
Joined
May 31, 2008
Is there any difference in the block, heads, cam, crank, etc. I can pick up a complete 85 engine very reasonably. Is it any good for building to make horsepower?


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Many have built 4140 blocks without issue. There were changes in deck height from 85 to 86 since they used different head gaskets. You will have to drill a oil return line in the block on the 85 (4140) block. I would try to stick with a 109 block if possible because if you do sell it one day the 85 block might scare some people off but the 85 block should be fine. It will just take a little more machine work with the taller deck and oil drain back hole for the turbo. I think there were small upgrades in the oil passages and the lifter valley might not be solid like the 109 block.


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ScottHeidinger said:
Many have built 4140 blocks without issue. There were changes in deck height from 85 to 86 since they used different head gaskets. You will have to drill a oil return line in the block on the 85 (4140) block. I would try to stick with a 109 block if possible because if you do sell it one day the 85 block might scare some people off but the 85 block should be fine. It will just take a little more machine work with the taller deck and oil drain back hole for the turbo. I think there were small upgrades in the oil passages and the lifter valley might not be solid like the 109 block.


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Thanks for taking the time to reply. So I guess the 109 and 4140 seem quite different. I was hoping the 4140 engine would have more similarities. Do any of the other components carryover to the 109?


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They actually aren't that different. There is a lot of good information on gnttype.org about the different parts used in these engines over the different years. Since the most updated was 30 years ago I would go with the latest version 109 block unless you're just trying to get your car moving with no budget. Today forged cranks are too cheap to use a stock cast crank in my opinion. The older 4140 probably has the same cast crank and I'm pretty sure it had the same 8445 heads. If I were looking for a block I would rather buy a N/A 1986-87 109 block and modify it for turbo use.


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ScottHeidinger said:
They actually aren't that different. There is a lot of good information on gnttype.org about the different parts used in these engines over the different years. Since the most updated was 30 years ago I would go with the latest version 109 block unless you're just trying to get your car moving with no budget. Today forged cranks are too cheap to use a stock cast crank in my opinion. The older 4140 probably has the same cast crank and I'm pretty sure it had the same 8445 heads. If I were looking for a block I would rather buy a N/A 1986-87 109 block and modify it for turbo use.


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I'm just trying to figure out if the engine and it's parts are worth anything. There is a guy local to me that bought a 85GN and is doing a LS swap. I can buy the complete motor for $400. I have a 87 GN but I know zilch about the HA cars. The only thing I really want is the intake if it's the same as 86-87. I need a core to turn in for a Champion I bought.


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If you don't want to send your stock one in you can post in parts wanted. It's getting harder to find a unmolested core these days $150-$200 bare when they pop up for sale. Sometimes even more $$


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ScottHeidinger said:
If you don't want to send your stock one in you can post in parts wanted. It's getting harder to find a unmolested core these days $150-$200 bare when they pop up for sale. Sometimes even more $$


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I actually did that. You are right on with the prices. I would like to keep mine. It's the original and I have never sold anything that came off the car. I could put it all back to stock in about a week.


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My stock GN engine is on a stand in the garage complete pan to throttle body. Including the turbo...


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Nice. I wish I was able to do that. I'm thinking about it. I have been contemplating a TA block and going for broke. Haha. Literally.


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