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Need first start/break-in info 66 Broadmoor

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Hi all,I just picked up a 66 Broadmoor with a fully rebuilt 7HP engine.I am told that it has break-in oil in the engine but has not yet been fired up.I would like to hear opinions on the best break-in procedure for these old aluminum block engines before I fire her up.Got a great deal on this beauty. The previous owner spent a lot of time restoring her and was almost finished when he had to sell due to health reasons. he did a really nice job on her and I aim to finish anything left undone. First I want to get her running and break her in properly.Here are a few pics.

Broadmoor 1.jpg

Broadmoor 2.jpg

Broadmoor 3.jpg




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Whenever I overhaul an engine, I run it at moderate, but varied speeds for a couple of hours, then drain and refill the oil. This gets anything left inside the block out, like dirt or even small metal chips from the overhaul. I also make sure I don't run it lean on the gas mixture. Otherwise should be good to go. Looks like a nice tractor!


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Looks nice, but that is an interesting mix of non-original colors schemes and stickers.

As for the break in procedure, I would also vary the speeds, but keep them up higher for a couple of reasons. If you are going to use this tractor for any real uses, you will be running at full throttle (at least I hope you will), so you want the engine to settle in at a similar RPM range. More importantly, the engine cools best at full throttle. It would be nice if the RPM could be checked to make sure it is at 3600RPM. The splash oiling system is also more effective at higher speeds. I would run the engine for no more than 5 hours on that oil and then add regular engine oil to it. I would run the regular 30w oil in it for probably 20 - 25 hours, then I would change over to synthetic oil. Let the dino vs. synthetic oil debate begin......

As a side note, I thought OEM pistons for the old aluminum bore flatheads were obsolete. Maybe I am wrong. I haven't looked for a piston for one in many years. Is there an aftermarket piston available now? Weren't the pistons for the aluminum bore iron coated? I suppose there are places that could coat a piston.

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Sounds like good advice everyone on break-in. Just wondered if there was any prep before the first start like a small amount of oil into the combustion chamber, a certain amount of manually priming her with oil, etc.

I have to assume the carb has not been adjusted yet since the engine has not been fired so I will have to be doing it all at the same time.

I have a tachometer to check/set the RPM now so that is a bonus.

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I looked into replacement pistons for my 64 and 65 Broadmoors a couple years back and apparently you use the newer pistons, you just have to use chrome rings due to these being high silica aluminum.

I have not rebuilt those engines yet though. Both had snapped connecting rods and need evaluating to see if they can be reasonably rebuilt.

Spinning that steering wheel is one of the first things I did. It's funny how often you find them backwards but I have seen a lot of photos of them that way.

Have not yet tried starting her up. The fuel tank had been stripped to bare metal and looked like brand new but was beginning to get surface rust on the outside so I gave it a good cleaning and then powder coated the outside. I have to reinstall the tank and finish connecting the wiring before starting her up.

The colors and decals do seem to be off in many ways. I do not know if the guy could not identify which were correct for the tractor or if he was not going for absolutely original and was choosing what he liked best. Either way she looks nice. I will probably replace the hood decals with those correct for a 707 and leave the rest as they are for now. I will concentrate more on original when I eventually restore the 64 Broadmoor.

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I was taught this method way back in 1975 at our community college by a former GM district rep who was my instructor. It's nothing new...


The hard part with our engines is giving them a load for any significant length of time. I guess go out and mow some tall grass???


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I have a snow blower I can hook up to add some load if needed.

I hooked up the electrical today and cranked her over a bit with no fuel. She had no spark though so I will have to check out the armature and see if it is good and properly spaced from the flywheel.

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