Rockin'D's engine overhaul

[BA80]

Doc got his SG out of a field, dragged it home and started fixing it. First thing was the engine was locked up so he spent a long time soaking the cylinders with penetrating oil and working to bust it loose.

Finally got it loose and everything fixed and working but it always used a lot of oil and gas.

Last spring he lost #1 cylinder and parked it. I figured he had broken a ring as bad as it used oil.

He purchased one of those $150 BB kits from ebay and it showed up the other day so today we proceeded to tear down the top end.

First thing when the head came off we found a BADLY burnt exhaust valve in #1 cylinder. So, there is the lost #1 cylinder.



But, that still didn't explain the oil consumption. 3 of the 4 pistons were washed well back from the edges so it was obvious the rings weren't sealing properly.

We pulled the cylinders and it was obvious why. The cylinders were rust pitted from sitting and seizing up.




Off to the machine shop to get the 1196 pistons fitted and the head repaired.

I know that several people here were curious about those inexpensive BB kits on ebay so I started this thread to take y'all trough it and we'll all see how it turns out.

[jwhughes3]

Interesting. What do you think burned that valve? Loose header/ bad exhaust gasket seal coupled with a lean cylinder?

John

[BA80]

Hard to say with the engine in the condition it is. Could have been rust or a chunk of carbon stuck in the seat allowing the seat to leak.

[XJOK2PLAY]

Wow, guys! I'm surprised it ran as well as it did, Doc!

[ViperRon]

I have suggestions for the big bore kit. First ask the shop if they want to bore them in or out of the cylinder. Some have a mount to where its easy to support just the cylinder and not the whole assembly. You can pop the cylinders out of the casting using an oven set to 400 degrees and they will fall out if upside down at about 350. It would be good to clean and paint them before putting them back in. Ask the shop to make small cuts at the end as these cylinders can deform with a heavy cut. Might be best to use a shop high speed hone to do the last clean up of a few mm worked great for mine as perfect as could be. If he bores it out and you have it tight to the book minimum on skirt clearance then the ring gap is perfect with the rings that come with kit.

I have a Mack Flare tip pipe set, air box standard, standard foam filter and running at 120 jets its too lean for mine had to go to 122.5 mains out of book float height. Good luck

[BA80]

Doc says he found someone to bore the cylinders assembled and fit the pistons for $150. If this guy gets it done right I may be visiting him.

I think assembled is the way to go because refitting the cylinders would cause warpage for certain.

[ViperRon]

150 is cheaper than I paid but I did not know anyone had to search for a local top notch shop. Those were my suggestions Japan seller told me the spec's are the same as for the original pistons for skirt and ring gap etc. At least clean the assembly before the bore rust even on the outside of cylinders is not your friend.

[BA80]

At least clean the assembly before the bore rust even on the outside of cylinders is not your friend.

If it has rusted between the cylinders and the aluminum housing then it will be the first time I've seen it happen. That part is only exposed to the oily crankcase environment.

[BA80]

Getting the base gasket scraped off ready to go back together....




Got the rebuilt head and bored cylinders back a while back.




Haven't been in a big hurry because of financial constraints and besides, Doc has this LG barn find to ride for the time being. It had sat for MANY years in a barn next to a 51 Willys pickup. Took us a couple weeks to get the bird crap and dust cleaned off and to get it running. Runs great. Doc has ridden it a lot of miles since.

Looks like hell but it hasn't given him any problems.

[trbig]

So.... did he get past the gasket scraping stage or did the beer drinking get in the way?

[BA80]

I just went in the house and took a nap. He was wearing me out with the gasket scraping. He'll be getting the pistons and rings on this weekend.

Came up with an idea for ring compressors, a couple of SS quick release hose clamps. Gonna get a couple and see how that works. They're 3/4" wide.

[trbig]

I've tried a couple different variations of spring compressors, but found it just ends up being easier with an extra set of hands feeding one piston in while you feed the other, then repeat. Usually with a set of rings popping out the bottom a time or two until you get the cyls pushed down over all 4. But.. I hope you find a better way because that part of it is a PITA.

[BA80]

Update......

Finally got Doc back over here to get this piece of furniture put back together.

Pistons and rings installed on the rods......




Doc cleaning the last of the old gaskets off the jugs.....




Fitting the jugs over the new BB pistons....



We found that just plain old hose clamp worked really well as a ring compressor.



Jugs went on fairly easily........





Cams installed, no problem.......




Now that it went back together fairly easily we checked the valve clearances. My thinnest feeler guage is .002" and the ONLY lobe it would slip into was #4 exhaust.

Cams will be coming back out to replace ALL the shims and attempt to get it closer.

We should have checked it on the bench but I wasn't thinking.

Apparently the machinist didn't dress the tips of the valve stems as he should have. I hope we can come up with thin enough shims to get it into spec.