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Discussion Starter #1
So when resurrected my 3.5 Carb V8 engine in my barn find 1983 RRC I changed a whole bunch of things and it ran great until now.

500 miles later I started to notice a misfire when cold. Week later and the misfire is noticeable when warm. Engine runs fine otherwise with good oil pressure, no smoke, normal fuel consumption and performance as expected (from a 125HP engine with a 1980's 3 speed auto box)

Checked compression last night: all 20PSI nr 7 5PSI. Oh dear. squirted in some oil and compression came right up to 120 psi. Looks like another teardown...

So what did I do: One side of the engine was left open and there was some very light surface corrosion in the bores so I did a really light hone on all 8. It is a low mileage engine with very little wear so I DID NOT change the rings. Some of the rings were stuck with a little rust so I freed them up. I had just received all the parts (but did not order rings) and just wanted to get it done. Picture shows my light hone just before closing up

I am guessing that this was a mistake: Light hone and old rings. I presume I messed up the seating of the rings.

Ordered new set of rings and gaskets. Hopefully can turn this around in a weekend.
IMG_0951_Canon PowerShot G9 X Mark II_0_10.2mm_8.0_20s_2048x1536.jpg
 

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Discussion Starter #2
Ok so I spent a few hours this weekend tearing down the engine. Since it was all put together a few months ago it all came apart quickly.

Non of the bores were damaged, but the hone had been smoothed out so I gave a it fresh hone/deglaze. This time I did a very thorough cleaning job. What is clear is that with the engine sitting for so many years some of the corrosion is too deep to be honed out although most are black marks and there is no pitting. The worst is probably Cyl 3 where you can feel the marking, but if you run your nail past there is no detectable ridge or anything.


Originally I had freed up the rings and just popped the piston back which obviously was a bad idea. This time I have removed all the rings and cleaned the grooves and I am waiting for new rings to arrive. Hopefully this time the rings will bed in correctly or else I need to look for a new motor. Yes I could have it overbored and then buy 8 oversized pistons but I can get a decent 3.5 motor for about $1000.
 

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Discussion Starter #3
Received my rings (very nice made in Germany!) and fitted in my cleaned pistons. I installed in the honed bores last night. They did go in much easier then 3 months ago when I fitted them with the old rings. Engine turns very smoothly and there is no indication the cylinder wall markings are affecting the rings (no binding or anything). Fingers crossed.

Unfortunately I ordered the wrong head gaskets so now I will be waiting for those to arrive before I can close it all up.
 
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