cooling fin interferes with mount bolt?

[Wheels]

Im switching out my old engine with a new one. The old engine (pictured) had the cooling fins on the #4 cylinder ground down to make installing the rear adapter for the mount easier.
I can't get the mounting bolts into the adapter without hitting the fins and I don't want to grind them off, Nor do I want a shorter bolt. Do I really have to grind off the fins? Shorter bolt seems like a bad Idea too. I'm open.

[efwd]

If your old one had ground down fins, what's the aversion to doing that same thing? The way you describe it, it seems geometry is geometry. Square peg won't go in a round hole. I would not want to use a short bolt myself.
Eddie

[Slyfox]

I also had that bolt break. so when I replaced it I went to a harder bolt. now the new one had a round head with allen wrench type. no need for grinding that area down. my old bolt was that type also. now ask me where I got that bolt, can't remember. I'm sure I got it local. sorry.

I think I went to Fastenal in Spokane.

[jmodguy]

McMaster Carr has a huge selection of hardware. www.mcmaster.com

[Wheels]

I actually have both styles of bolt, (hex and standard) The hex doesn't fit either.
I'm pretty sure its a grade 8 bolt that I am putting into that aluminum case. I don't think it will break, but, it looks like I will actually have to grind on the cooling fin to make it work or decrease the thread engagement with a shorter bolt. (Not) I"m going to make sure I don't have some wierd bolt that isn't stock to the IV. I"ll call Kitfox Monday and order all new hardware and compare the ones I removed from the previous builder's install. I just can't imagine the original 912 requiring the fins to be ground down. I"ll do it, but I won't like it.

[Slyfox]

my advice is to do everything exactly like on the other motor. But I would put the round head bolts in that location, it is very tight and you won't be able to put a good socket on it to torque it down if you use those big bolts. Just do things like before and get this unit done so you can fly it again.

[Wheels]

Well, as much as it pained me to grind on a brand new engine, I made the relief on a fin so I could get the bolt in. I just need to assemble it now. Im actually struggling with attaching the engine and mount as there is just enough pressure from the rubber mounts to make alignment of all the bolts difficult in a one man band.

[kmach]

I found it easier to assemble the engine mounts on the engine on the work bench then move the whole engine with engine mounts to the firewall and bolt it on.

[Slyfox]

I found it easier to assemble the engine mounts on the engine on the work bench then move the whole engine with engine mounts to the firewall and bolt it on.

that's what I did. then I used an engine hoist with adjustable straps. worked great.