How much can you over bore a 8-98 and 8-105?

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17 Dec 2017 00:53 - 17 Dec 2017 01:00 #33868 by curtiss
curtiss created the topic: How much can you over bore a 8-98 and 8-105?
A while back I picked up a spare engine and the tag has a GU68870 and I was led to believe it came out of a boat tail that had a hotter engine installed in it but I am not quite sure of the year. It has an updraft manifold so maybe a 8-98?

This engine was out in the elements for many years before I rescued it and I just started taking it apart today. The bottom end and valve area looked decent, no signs of corrosion. I wish I could say the same for the cylinders, we will drop the crank and try to get the pistons out tomorrow :)I have never had one of these apart before so I have never seen so much safety wire and cotter pins securing bolts in an engine ever before :)

Here is my question, looking at the condition of the cylinders a few are pitted pretty bad and they seem to still be the original 3 inch bore. How much can you safely over bore or can these be re-sleeved?

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17 Dec 2017 02:22 #33869 by pete kelly
pete kelly replied the topic: How much can you over bore a 8-98 and 8-105?
You might want to soak the engine in penetrating oil repeatedly and delay the disassembly for a couple weeks
Pete

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17 Dec 2017 02:31 #33870 by 1748 S
1748 S replied the topic: How much can you over bore a 8-98 and 8-105?
I agree with soaking the cylinders and pistons as already posted. Puechase some Aerokroil from Kano Labs online. The Aerokroil will cut thru all that rust and loosen it up. Nothing works better.

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17 Dec 2017 18:04 #33871 by Curt Schulze
Curt Schulze replied the topic: How much can you over bore a 8-98 and 8-105?
A couple of years back a scientific study was done:
Penetrating Oils

Machinist's Workshop Mag recently published some information on various penetrating oils that I found very interesting. Some of you might appreciate this. The magazine reports they tested penetrates for break out torque on rusted nuts.

They are below, as forwarded by an ex-student and professional machinist. They arranged a subjective test of all the popular penetrates with the control being the torque required to remove the nut from a "scientifically rusted" environment.


Penetrating oil Average load
None 516 pounds
WD-40 238 pounds
PB Blaster 214 pounds
Liquid Wrench 127 pounds
Kano Kroil 106 pounds
ATF-Acetone mix 53 pounds


The ATF-Acetone mix was a "home brew" mix of 50 - 50 automatic transmission fluid and acetone. Note the "home brew" was better than any commercial product in this one particular test.

Our local machinist group mixed up a batch and we all now use it with equally good results.

Note also that "Liquid Wrench" is almost as good as "Kroil" for about 20% of the price.

Steve from Godwin-Singer says that ATF-Acetone mix is the best and you can also use ATF- lacquer thinner 50 - 50 mix.

ATF=Automatic Transmission Fluid

The bitterness of poor quality remains long after the sweetness of low price is forgotten.
Be of Good Cheer
Curt

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17 Dec 2017 21:20 #33872 by 1748 S
1748 S replied the topic: How much can you over bore a 8-98 and 8-105?
ATF acetone is good but using it comes with cautions. Acetone is absorbed and will not leave the body easily. It builds up in the kidneys. Should you choose to use it protect yourself.

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18 Dec 2017 03:24 - 18 Dec 2017 03:29 #33873 by curtiss
curtiss replied the topic: How much can you over bore a 8-98 and 8-105?
We completed taking the engine apart today, though a few of the cylinders were in bad shape we were able to get all of the pistons out. All of the rod and main bearings still looked good and had oil. The pistons and valves will need to be replaced and an overbore or re-sleeve in the holes. The cam looked good but the timing chain was stretched a bit.

Will have to hit a machine shop to see what can be done.

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