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Thread: Visible rust on pistons

  1. #21
    Thank you Pelago and gmwillys. You clearly have done this before and you both give me hope. I’ve been diligently and gently scraping, cleaning, oiling, and massaging that top half while I pick away to get it down to frame. I’m in no rush at all as I tend to the Buick also. I get my engine hoist back from being loaned out in January and I’ve sourced a reputable engine rebuild shop. Gonna wait till after the holidays to try and move the pistons. Keeping busy, staying warm, and picking away... a rather perfect winter, I’d say. I’ll let you know how it goes... Thanks again.... Tom

  2. #22
    Super Moderator gmwillys's Avatar
    Join Date
    Aug 2017

    Patience is the name of the game. Jeeps are simple machines, but they are a lot more quirky then your Buick in comparison. A GM corporate engine is more forgiving, and will run/perform descent even when everything is not perfect. For an example, I had a neighbor that purchased a '70 Olds 442 W30. He was a body guy by trade, but mechanicals scared him. I watched him do a long smoky burnout down the block, but I could hear a bit of a miss at the higher RPM, at the exhaust. We checked the plugs and found that two cylinders on the right bank were not burning consistent to the others. I checked the valve lash and found to exhaust valves were loose. When adjusting the lash, the two that were loose needed to be tightened much farther than they should have been necessary. Upon further inspection, one exhaust push rod was bent, and the other was a temporary adjustable push rod used to measure correct length for ordering the proper length after a cam change. The push rod was never meant to be used for running the engine. The neighbor then decided that he would have his buddy the drag racer rebuild the engine for him. That went alright until the next summer when he would cruise around town. He started consuming a quart of oil every time he went to town. After looking at the build sheet that the drag racer put together, I found out that he used single ring light weight pistons. The pistons were designed for low miles, (a 1/4 mile at a time). This is why it would consume so much crude while driving around.

    In my opinion, when looking at a machine shop, I would look at one where there is at least one guy who is in their mid to late 60s or older. These guys understand flat heads and cast iron. On the M38A1 that I did the body work on, the engine was sent out by the owner. The machine shop was recommended by the local military vehicle club. When the owner tried to start it for the first time, it was hard to start and ran like crap. When it did start, it leaked all over. The cam was not in time with the crank, so the timing was way off. Half of the gaskets were either torn or the surface wasn't prepped for a good seal. Whatever the shop had charged, it was too much for what they did. Due diligence is important to ensure you have a good result. Do your home work on the reviews of the shop, plus talk to anyone who was dealt with them.

  3. #23
    Senior Member pelago's Avatar
    Join Date
    May 2016
    easter north carolina
    read and heed!!
    rebuild is first dismantle, then measure, then repair and finally re assemble. for strict dollars and sense you reassemble, you be present when machine shop measures, you decide on new pistons and what size (oversize pistons readily available). you be there when crank measured and inspected, you decide on how much crank metal to remove (bearings all sizes readily available) putting one of these back together is not all that hard. only thing i would do is to align engine for cyl one to fire and mark the timing gears with a punch and photgraph it for re assemble. hell if old retired infantry guy like me can do it,,,,,,,,,,,,,,,,,,,,,,???

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