Hello,

A friend of mine and I are relatively new to nitro, we practice together every week. He’s been over tightening his engines into his buggy and has $1000 worth of motors with the mounting tabs busted off, all on the left side. Engines are in otherwise nice shape, I’d like to help him find suitable new cases.

Any definitive information on which OS cases would be compatible with the following? Or is there a more general rule, like all VZ-B and XZ-B are interchangeable, but not B210X, or vice versa, whatever?

Protek Samuri 321B
Bullit B-221
OS B2103 type S

You should post some pics cause I'd like to see it!!!

Guys you do not need to crank down on these screws and bolts as hard as you can. If you strip a bolt you got it too tight especially you break tabs off. On my engines my head bolts and cover plate I use the DEWALT 8v with #10 and check.

The ears are not breaking because they are too tight. They are breaking because either the mount needs to be trimmed as its binding against the case and not sitting flat naturally so when you torque it down from the bottom and it becomes flat all the tension and force it took to get it to sit flat is now in the ear of the case. Or its just plain old crooked and breaking during flex. The first thing is Super common on os engines and even states to check this in the manual

this^
ive heard of crankcases breaking from hard landings or chassis flex hitting the clutch bell which breaks the case but you can't tighten the engine mount screw enough to snap the ears the screw goes in. If you have a 2 piece motormount or a quick change mount then put the two mounts on loose and set the engine into the car and so those little ears can move a tiny bit when u tighten the mounts on the quickchange. Then once it's tight u can secure those bolts that go threw the ears. This will ensure your mounts that go on directly to the ears are right when u take the engine out for cleaning and then put it back in. If u only have the stock mounts that connect to the ears only on top and can't be removed without taking the engine off the mounts then put the mounts on loose but tight enough there's only a tiny bit of movement and then go to the bottom of the chassis and tighten them once they are at the correct mesh and then go back and tighten the top screw that go threw the ears.

Really u want the quick change mounts so you don't have to unscrew those 4 screws that go threw to engine ears. Nor will u need to unscrew the chassis screws on the bottom that u set mesh with. The mounts are two separate pieces. Look them up n u will se

Thanks for the replies guys. He’s switch over to quick change mount on everything. Has ran maybe half a gallon so far and all good!

thats the fourth newer os case that Ive seen this happen too, and its always pipe side hmmm. I thought we were talking the xz case, there has to be something dimensionally off with these motors. (edit)I see the second pic is an xz based bullet motor

Yes sir, it's a B221. How do you tell it's an XZ case? Does that mean any XZ case will work for the Bullit?

the 221 would be square stroke so it would need a 2101 or 2102 case, they share the same mold with the XZ series but could quite possibly have different machined dimensions due to the difference in bore size.also the engine is crooked on the mount in the second pic

On the first pricture, why is there skuffmarks on the back og the enginecase under the mounting tan? That is strange ad looks like someting ha rubbed the case.

And what car is this?

no matter what something has to flex for this to happen, no screw issue, clutch bell hitting on the angled engine, flywheel smacking the ground each time?
Something i used to see was how fast front bearings of engines wore when people would push down really hard to start their engines.

Curious what was going on in the first pic, a flywheel shouldn't wear that much unless its hitting the ground, the exhaust gasket is all smashed up, maybe experience comes into play here?

i've broken Many drivers over the years torquing these bolts down before big race A-mains.

Thank you guys for all the replies. Absolutely experience and driving style both come into play here. No question. He's rougher on stuff that I am, I've yet to break a case. (FINGERS CROSSED). The car is a D819, which has motor mount "pills" to ensure perfect alignment, but it does look like the motor is a little crooked in that picture. I will check it out to see if all of the pills are turned the right way. That would definitely foul things up if that was the case. I know he has since gone to a quick change mount, but this was after all were broken.

I found my buddy a free old used case for his B221 and swapped everything over last night. I'm going to put it in the car and go over everything with him just to make sure something isn't blatantly off

its not about those mesh adjuster pills, how how the engine is mounted to the engine mount, normally i push the engine all the way forward to square it in the mounts , if those mounts that attach to the engine tabs are at an angle they usually hit the side of the case underneath and then when the chassis flexs its putting pressure on the bottom of the case and the engine tab...