Bastard motor

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kmr0290
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Bastard motor

Postby kmr0290 » Tue Nov 17, 2015 8:42 pm

Ok guys don't tear me up too bad for this. lol I'm just curious. If you were to take a 360 crank and put it in a 320 using the 320 rods what Pistons would you or could you run??? 360 cranks aren't easy to come by but I'm wondering if it's possible. I've never done piston to valve measurement but I'm sure someone has. Or maybe a 320 crank with 360 rods idk??? Just curious. :old_glory:
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Re: Bastard motor

Postby kmr0290 » Tue Nov 17, 2015 8:58 pm

Sorry guys. I have no idea how this got in airboat sound??? Someone please throw it over in the aircraft forum. Thanks kmr0290 :scratch:
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Gary S
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Re: Bastard motor

Postby Gary S » Wed Nov 18, 2015 6:44 am

I've never done it but I think you have some case mods to do to get clearance to rotate.

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Re: Bastard motor

Postby JCGator » Wed Nov 18, 2015 8:40 am

you'd have to modify the 320 case a little bit to account for the longer stroke on the 360 crank... read on here it was relatively minor and can be done with a dremmel. at that point why not just build the rest out as an O-360? also i've seen a few 360 cranks on here in the classifieds and i think gary at outlaw has some.
10'6" Taylor Hull. Lycoming 170 hp - O-320 w/ 480 AV jugs

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Re: Bastard motor

Postby kmr0290 » Thu Nov 19, 2015 6:35 am

Actually I already have a 360 case. The rest is 320. Lol. Jugs,rods,8.5 to 1 Pistons. Etc. there is a wide journal and a narrow journal crank for the 360. Maybe you don't have to clearance with the narrow version. I've rebuilt a 180 that was built with a narrow deck 320 block. They ground the block on each cyl port on the block not a lot though. A machine shop would have done a way nicer job imo. But it worked.
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Re: Bastard motor

Postby kmr0290 » Thu Nov 19, 2015 6:40 am

Oh lol. As for the why not build a 360? In my back woods way of thinking you possibly could make more hp with the 360 crank and the shorter 320 jugs. That's if you have valve clearance. It definitely would be a high compression engine but I'd be more interested in the stroke. :old_glory:
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Re: Bastard motor

Postby rhodes » Thu Nov 19, 2015 10:07 am

do not use the 0320 rods. you have to use 0360 rods because 0320 rods have the rod nuts on bottom of rod. they will not clear the case no matter how much you cut the case. we did this back in 1977,0360 crank,rods,0320 cyls. the comp. was so high,you could not start the engine with a starter. had to hand prop.

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Re: Bastard motor

Postby kmr0290 » Thu Nov 19, 2015 11:23 am

Yeah I was thinking you would have to use the lowest comp. pistons u can find. Maybe some 7.5:1? There may be some shorter ones from turbo engines. Think I saw some 7:1 with valve reliefs in them. U could always get customs made but that would defeat the point.
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Re: Bastard motor

Postby krazymatt » Thu Nov 19, 2015 3:57 pm

You could run the 360 crank with the 360 rods and the 320 cylinders with a spacer plate or just put the 360/540 rods in with the 320 crank and the 320 cylinders

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Re: Bastard motor

Postby kmr0290 » Thu Nov 19, 2015 5:24 pm

Just gunning the 360 rods may get the comp ratio down enough to run super unleaded or u think it would be an avgas or race fuel only? In my experience anything over 9.5 or 10:1 doesn't like auto fuel. And hell on starters and impulse springs.
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Re: Bastard motor

Postby Gary S » Fri Nov 20, 2015 5:59 am

Your doing all this and you worried about avgas? Everything you talked about doing raises compression, and that needs avgas.

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Re: Bastard motor

Postby kmr0290 » Fri Nov 20, 2015 6:14 am

I know it does. But it would have to be a Sunoco or vp. Avgas would be nearly impossible for me to get. Thanks for y'all's replays. Have a good thanksgiving
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