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Balancing and engine assembly
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Amostafa
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PostPosted: Sat Jul 08, 2017 8:05 am    Post subject: Balancing and engine assembly Reply with quote

So to start I have all the books for Tom wilson to Bill Fisher etc.

So I had to replace one rod because the brass bushing on the small end spun.

The new replacement rod is about 16.1 off from the heaviest to the lightest.
1: 470.5g replacement one original one was 484.0
2: 485.9g
3: 484.8g
4: 486.6g

Now the pistons are all with .2 or so g of each other.

Is it safe to take 16 or so grams of the rods and piston on the other three? Or does anyone know a place I can send my one rod to to get a new bushing pressed in.

Any good input would be really helpful.
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chrisflstf
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PostPosted: Sat Jul 08, 2017 9:48 am    Post subject: Re: Balancing and engine assembly Reply with quote

16 grams is over half an ounce, no way you want to remove that much from the other 3. Either replace all 4 rods or have your old rod re-bushed
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nsracing
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PostPosted: Sat Jul 08, 2017 9:48 am    Post subject: Re: Balancing and engine assembly Reply with quote

Don't 'balance' rods by just the total weight. Weigh the bigend first = this is rotating weight. The reciprocating weight is the small end = weigh the whole rod.

Get the big end all the same first. You do this by a hanging device on top of the scale.

The small end weight is calculated by taking the whole weight of the rod. To balance, take weight off the small end.

Any shop should be able to push and size a new bushing for the smallend.

Are you balancing the whole assemby? Crank - flywheel - pulley -pressure plate.
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Amostafa
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PostPosted: Sat Jul 08, 2017 10:15 am    Post subject: Re: Balancing and engine assembly Reply with quote

nsracing wrote:
Don't 'balance' rods by just the total weight. Weigh the bigend first = this is rotating weight. The reciprocating weight is the small end = weigh the whole rod.

Get the big end all the same first. You do this by a hanging device on top of the scale.

The small end weight is calculated by taking the whole weight of the rod. To balance, take weight off the small end.

Any shop should be able to push and size a new bushing for the small end.

Are you balancing the whole assembly? Crank - flywheel - pulley -pressure plate.



I was only planning on doing a static balance. Its a big bore 40hp and I don't plan revving this thing past 4k. Do it you think it worth a dynamic balance for this mild setup

Also I just moved here to Ohio for South orange county and don't know a speed shops that I can trust as of yet to balance my assembly.

Thanks all for the feedback
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modok
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PostPosted: Sat Jul 08, 2017 1:07 pm    Post subject: Re: Balancing and engine assembly Reply with quote

The big ends and small ends should be checked for size, and the rod should be checked for alignment also, when rebuilding an engine. Any engine. If that's not in the book put it in there.

If you want to do a good job, then in addition the balance and lenghs should be checked and corrected.

It is possible to lighten the other rods to match, but I really doubt it would be the best way to go.
Lighten one, then you have two pairs. 1-3 and 2-4
Yeah it's not right but neither is what you are doing, so make the best of it Wink
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Amostafa
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PostPosted: Sat Jul 08, 2017 2:00 pm    Post subject: Re: Balancing and engine assembly Reply with quote

modok wrote:
The big ends and small ends should be checked for size, and the rod should be checked for alignment also, when rebuilding an engine. Any engine. If that's not in the book put it in there.

If you want to do a good job, then in addition the balance and lenghs should be checked and corrected.

It is possible to lighten the other rods to match, but I really doubt it would be the best way to go.
Lighten one, then you have two pairs. 1-3 and 2-4
Yeah it's not right but neither is what you are doing, so make the best of it Wink


I just ended up rebuilding and the one. Then balanced them .1 gram statically on the big end. It should be good. Sizes was the first thing I checked and length.
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modok
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PostPosted: Sat Jul 08, 2017 2:17 pm    Post subject: Re: Balancing and engine assembly Reply with quote

already? you work fast! Very Happy
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Amostafa
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PostPosted: Sat Jul 08, 2017 4:04 pm    Post subject: Re: Balancing and engine assembly Reply with quote

Well having my buggy down and it being my only convertible in the summer is a real bummer. So fast work means I can drive sooner than later.
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Amostafa
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PostPosted: Sun Jul 09, 2017 8:22 am    Post subject: Re: Balancing and engine assembly Reply with quote

Here is the setup I used below. Balance it was made with piston pin and inscidence meter base.


Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.
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modok
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PostPosted: Sun Jul 09, 2017 1:55 pm    Post subject: Re: Balancing and engine assembly Reply with quote

Better than nothing but I doubt that is accurate to 1 gram, because you ar not finding the center of the big end. I recommend using skateboard wheels and bearings. A skateboard bearing will fit the small end, and a wheel can be ground to fit the big end. Pictured here.
Image may have been reduced in size. Click image to view fullscreen.
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vwjetboat
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PostPosted: Sun Jul 09, 2017 2:24 pm    Post subject: Re: Balancing and engine assembly Reply with quote

modok wrote:
Better than nothing but I doubt that is accurate to 1 gram, because you ar not finding the center of the big end. I recommend using skateboard wheels and bearings. A skateboard bearing will fit the small end, and a wheel can be ground to fit the big end. Pictured here.
Image may have been reduced in size. Click image to view fullscreen.

what a nice variety of custom tools..whats the short pushrod for?
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modok
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PostPosted: Sun Jul 09, 2017 3:49 pm    Post subject: Re: Balancing and engine assembly Reply with quote

Degreeing cams

The dead-blow hammer is one of the best tools I ever made. Could not live without it. It's hollow, full of BBs, packs a strong whallop Razz
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nsracing
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PostPosted: Mon Jul 10, 2017 4:38 pm    Post subject: Re: Balancing and engine assembly Reply with quote

Nice tools, Modok. I am not a purist...but I have to say you gots some tools.

I have made tools in the past for a one-time job when I needed to make a small cut and did not have the right cutter for it. Or to remove something and did not have the tool. But I will always make the effort to not do that job again until I have the proper tool.

I like the tool that I make to be a thing of beauty and a sight to behold. I cannot imagine Michael Angelo slapping paints in the chapel 'trying to make-do'. Very Happy
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