Nice build man! Can you upload some video to youtube? It would be awesome to see it running!

Saw this for sales Wisconsin. Legend status obtained. Says os 26.

Looks like someone had a lot of spare parts across different brands lol. The engine is probably a OS FS SC. There are a couple threads on here somewhere of folks adapting them to work in cars.

My life exploded for a few years, but this past summer I finally bought a phone holder I could stick on my RC controller, so I could finally record a running video of my FS-40S-CX powered HPI Bullet:


I also did a bunch of precision cutting work inside the crankcase, improving piston-ring blow-by flow from the crank chamber through the camshaft chamber and up into the rocker arm chamber, to improve oil-vapor lubrication. Oil-vapor lubrication is the only automatic lubrication this engine has, so it's critical that it works properly. My early experiments with this engine inadvertently disrupted the oil-vapor flow, which was already mediocre from the factory, and thank goodness I have a FLIR camera so I was able to see the camshaft chamber with its sliding-gear drive being the hottest part on the whole engine.



Nearly everything I've done to the engine since then has been in the service of improving oil-vapor lubrication.









This in turn allowed me to simplify the PCV system to just a single vacuum line connecting the idle opening of the carburetor to the rocker arm chamber.







And I chased down some intake restrictions that I had already known about that I just hadn't gotten around to dealing with yet, like a hard step between the carburetor adapter and the intake plenum, and hard steps between the edges of the intake and exhaust valves and the top of the cylinder sleeve.







I also replaced the crankshaft and camshaft bearings with ceramic/stainless-steel bearings while I had the opportunity.

I forgot to mention: Based on this truck's speed of 39mph as measured by GPS, and accounting for the drive ratio and the tire diameter and all that, this engine is pulling about 20,900rpm under load on flat ground, which is a damn near exact match for the 21,000rpm O.S. says the engine is capable of.

Very nice. Seeing that video makes me want to pull my 4 stroke stuff back out again.
By the way, 20-21k is about what I managed on the FS62-V as well. Seems low 20s is about as high as you're going to get with these.

That's fine. Insane RPM was never the advantage of 4-stroke engines of any size. With significantly stiffer valve springs and better internal balancing and a big-block carburetor, it's probably possible to get meaningfully higher peak RPM, but that would come with significantly increased heat and drag and valvetrain wear. Not worth it in my opinion, not at this point in time where these engines are long gone from the market. The big win nowadays is making them work reliably, and well enough to be fun to drive.

Speaking of which, I strongly recommend the PCV mods I did to improve lubrication.

That's certainly an interesting modification. I will say though, my 62v had no issues with valvetrain wear. I didnt track the fuel usage on it, but it was several gallons for sure. Top notch engine.
There's an FS64-V out there now. Makes me wonder how it would do.

There's evidence from OS' own modifications to the crankcase design over time that they were iterating in the direction of having a PCV system. They just never quite got there.

are you still around? Running this? Sent you an email

massive!!! I’d like to talk about your project if possible 👍

Sure, but if you wouldn't mind, please delete the photos from your quote, so your reply isn't super long. 🙂 What questions do you have?