Hello, i have an Alpha Trainer 40 which my wife got me 2 years ago, well the evolution engine blew up in short order ($80 engine that came with the plane so oh well) now i have a brand new OS.46AX-i for it that i got for xmas, the problem is the original motor mount is set up for 4mm mounting bolts and the OS is set for 3mm, and i looks like the mount is too wide as well, any suggestions on what mount to get? and will i have to redrill the firewall to do it?

You may have to redrill. It is no big problem. Take the old one out, and find one that's close at the local hobby shop.. Or, you can get one of the Universal type that mount the engine in a strap. Not the best way, but I have 2 like that, and they have been more than adequate.
You have a great trainer, and now a great engine to go along with it. I just wore out my last evo 45 trainer engine, and used a Magnum 52 four stroke to replace it. It's not as fast, but I like the 4 stroke sound, and it really is enough to train with. As long as you mount it even close, it will work. Of course, the closer you keep it to center, the better. The 1 or 2 degrees of offset thrust is already in the firewall, you shouldn't have to worry about that.

I'd be more concerned with why the Evo blew up. Maybe you were running too lean?

Its nice to see a flyer recommend an LHS, instead of online, mine is scarce for nitro planes because nobody buys anything there, save more me and a few people. But they order it all for me and are quite competitive with pricing so im happy, we need these stores so if we break a prop on sunday we dont have to wait 3-4 days for a new one from the internet.

And i just realized i had a brain fart, i forgot the dang bolts go through the straps not the engine block! I swear i get my best ideas when im tired!

Thanks guys

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My Alpha 40 RTF came with the "strap" type motor mount, so it wouldn't matter what size bolts the engine wanted. It sounds like yours came with a different type of mount.

It shouldn't be a big deal to drill new holes and put a new mount on it. I actually had my firewall pop right out on a hard landing. When I repaired it, I cut a new firewall (minus the mounting tabs), installed new blind nuts, and then epoxied it right on top of the old firewall, with tri stock braces. It did not noticeably affect the CG. You could do something similar if re-drilling the existing firewall and getting the blind nuts installed is too difficult.

I would also be concerned as to why your Evolution died so quickly. The OS 46AX is supposed to be the about the best engine out there, so you should have no problems with that one, just make sure it's on the rich side.

Good luck

Edited to add picture.

I'm with Minnflyer engines just don't blow up unless it's running too lean..whether it's an Evo .40 or an OS .46 AX they will all blow up when run too lean

i did run her a little lean once which resulted in a whuupped lower rod bushing, no matter ive got the OS now and i'm a lil wiser on tuning an airplane engine these days

That engine has a 3 year on it. Send it in to horizon and get a new one. Dennis

the carburetor was also bad, the o-rings got so loos on the needles that they would spin out as the engine ran, and thanks but i already threw it in the garbage and have installed my O.S.

i wish you woulda thrown it in my garbage... i fix them no matter what!!!

if i coulda thrown that far i woulda, bearings were all rusted out too from lack of after-run, i thought i blew the motor last summer so it has sat for almost a year with no after run maintenance, trust me you didnt want that thing, although to its credit it held my trainer in a hover when it was in good condition

and another thing OS didnt give me an exhaust gasket for the muffler the engine came with, they normally do dont they?

no, they don't, i don't use them on any motor, although the evolutions kinda need them because of the quality of the fit between muffler and motor.