540 short jug info.

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Kmr320
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540 short jug info.

Postby Kmr320 » Sun Feb 10, 2019 2:26 pm

Here goes. Went look at a supposed 540 260 yesterday. And as usual the owner wasn’t even close. Lol. “I just ran it” lol. So I know it’s a 540 case and sump and hopefully crank. It’s got angle valve 480 cylinders on it and the owner said he had to get a piston cut down once after a jug replacement. So my question is would it be a 540 crank,480,320 rods and a milled piston or is a 480 crank possibly in there? Also if a person like myself didn’t want a hot running high compression engine like this why couldn’t you get some low compression pistons made and get back to normal? Also this motor does not have spacers. Thanks y’all ideas/info is appreciated

woodlineO540
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Re: 540 short jug info.

Postby woodlineO540 » Sun Feb 10, 2019 8:58 pm

More than likely it’s a short Jug engine it’s a 540 crank 480 rods and cylinders. the Pistons are back cut to clear the crank on account of that short rod. You can Machine the Pistons probably as low as 9 to 1 compression that is ballpark

Gary S
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Re: 540 short jug info.

Postby Gary S » Mon Feb 11, 2019 6:49 am

Why?

BobBrack
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Re: 540 short jug info.

Postby BobBrack » Wed Feb 13, 2019 1:16 pm

The theory behind this setup is the piston goes down farther in the cylinder. Thus bringing more air into the cylinder. It also rises higher in the cylinder. Thus making higher compression. I have even seen them with the 540 rods installed. The rods have to be machined in order to turn the rod bolts around. I personally think this combination started because it's easier to find and a lot cheaper to find 320 rods and 480 cylinders. Most people buy 6 540 rods. Have space plates made to go under the cylinders. Get longer push rods and tubes. Put it all back together with correct pistons and run it like you stole it.

midnight rider
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Re: 540 short jug info.

Postby midnight rider » Mon Feb 18, 2019 4:45 pm

Im currently running a short jug 540. They are interesting motors. They are a high reving motor. From 2700-3400 They are a rank. Depending what cam you have and if it has 480 vs cut down 540 cylinders. They like the higher rpms vs the lower.

midnight rider
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Re: 540 short jug info.

Postby midnight rider » Mon Feb 18, 2019 4:57 pm

There’s no spacers on mine either. Mine has a 540 crank,cut down 540 cylinders, and a pretty rank cam.
Don’t know what rods he used. But it never gets too hot. Here’s a pic of the cyl length and current oil cooler set up
Attachments
image.jpg
image.jpg

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Tue Feb 19, 2019 8:57 am

Well I know how it sounds to the guys trying to make more power. Lol. But I’d rather have a cool running less temperamental engine. It’s goin to be mostly a hunt boat and occasional ride. And I can’t touch a straight valve 260 for the price he’s asking. So if I can get the compression down it would be fine until I can get a set of 360/540 straight valve jugs.

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Tue Feb 19, 2019 9:01 am

And you know I may be able to go through the mags and jet the carb right and get it to crank good and run cooler. Or even back the timing down some. It’s still gonna be a couple weeks before I get it home. So we’ll see then.

boostedigo540
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Re: 540 short jug info.

Postby boostedigo540 » Thu Feb 21, 2019 3:23 pm

You can make it a straight valve by changing from jug out. May have to put 540 rods in it if it doesn't have them. gimme a call if I can help bud. 8636980383

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Sat Feb 23, 2019 9:10 am

Thanks bud. I appreciate it. I’ve got 4 n/d s/v jugs and 4 rods that I could use. Just find 2 more. That’s what bothers me about the motor. The narrow deck stuff just isn’t as easy to find any more. And here in Louisiana it’s even harder. Especially good cylinders.

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Tue Mar 05, 2019 6:22 am

Looked at the motor again Sunday. Hopefully we can make a deal this week and bring it home. One thing I did notice was it had springs on the pushrod tubes. Never seen those before. I’ve found a guy with a set of spacers I can get. But until I get it home and pull a jug off and see what piston & rod combo it has I’m kinda just guessing. Anyone have any idea what H.P. this thing woulda been ? Oh. And the owner said the engine was built in Florida and the case was painted red. He said it was specific to a certain builder. Who knows. :scratch: :old_glory: thanks yall

SWAMPHUNTER45
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Re: 540 short jug info.

Postby SWAMPHUNTER45 » Tue Mar 05, 2019 7:14 am

We alter stroke on engines albeit not A/C but the internal dynamics are the same. When you use a short rod it can add pressure to the skirt of the piston referred to as the side load. As such if the piston is not a very high quality or enhanced design the skirt can crack. A common thing to look for in short rod engines is cylinders that are out of round because over time the side load can wear the cylinders in an egg shape. It also causes increased piston pin movement and why in such an application to our platform a bushed floating pin would be utilized.

If you seek a engine that is simple and basic maybe this one is not your best choice.

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Tue Mar 05, 2019 8:07 am

I gotcha but the pistons on an a/c motor are prolly twice as thick as a auto piston. And all are floating pin to my knowledge. I’m not worried about simple. The heat issue is my deal. As I don’t have access to av gas. And I’ve built quite a few. And on pump gas (96)it will detonate at anything 10:1 or over. Even if I had to replace the whole top end the price is the only way I’d ever be able to get into a 540.

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Wed Mar 27, 2019 9:03 am

Soo, I bought it. It’s mine. It’s home. :cheers: cranked her up 65psi oil pressure and no smoke. It feels strong but I really couldn’t get down on it because the prop is horrible. Got it off the boat last night and on the engine stand. If y’all wanna watch the journey I’ll share. But I’ve no idea how to post pictures.

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kwanjangnihm
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Re: 540 short jug info.

Postby kwanjangnihm » Thu Mar 28, 2019 9:25 am

Kmr320 wrote: If y’all wanna watch the journey I’ll share. But I’ve no idea how to post pictures


Select Post Reply, look for the Attachments tab, click Add files, point to photo on your computer and select open, you will see the file name, file comment, size & status - select Place inline. Your photo will be added to the thread. After a few times you are a pro at it. :thumbleft:
" I don't care who you are back in the world, you give away our position one more time, I'll bleed ya, real quiet. Leave ya here. Got that? "

Kmr320
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Re: 540 short jug info.

Postby Kmr320 » Thu Mar 28, 2019 8:33 pm

33C60A38-BE9A-478A-802F-5E07F48342EB.jpeg
778FBE22-5F13-47AA-AB0E-8553221AD0D6.jpeg
there she is. Oil leaks,dirt daubbers n all


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