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Finding the right scale.

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GPGoverMPG
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Finding the right scale.

Post #1 by GPGoverMPG » Thu Dec 14, 2017 4:58 pm

Getting engine from wrecking yard and will be doing a medium performance rebuild. Need to know some weights so I can get correct scale. I'm going to use 40 over H519P pistons and stock 300 rods. I want a pretty good scale but don't want to purchase more than I need. So with pistons, rings and pins I can make them match the lightest set. With rods do I need to match big and small ends as well as overall weight? I plan on sending crank, balancer, new flywheel and pressure plate to machine shop for grind and polish. Can they balance crank without knowing bob-weight or should I only get this done after finishing reciprocating parts? 300s have good primary balance so I wasn't sure if it mattered. I figure 5500 RPM will be max it ever sees. Running MSD 6AL with 5600 Limit that will start shutting things down 400 RPM lower. Thanks forward

H519P 40 over weight?
Stock rod weight?
Recommended scale maybe?
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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THE FRENCHTOWN FLYER
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Re: Finding the right scale.

Post #2 by THE FRENCHTOWN FLYER » Thu Dec 14, 2017 5:56 pm

I do not have the weights you seek.
I use a double pan balance to balance mine (think - scales of justice) with a vernier fine adjustment to +/- a half gram..
It is desirable to match the entire set, it you can afford it in either time or money.
It is most appropriate to match both the big ends and small ends plus overall wt.
Most competent machine shops have look-up tables to tell them how much bob weights to bolt on. You can use the stock pieces, as the weight differences between stock and aftermarket matter little (something like affecting fifth-order magnitude only - virtually nil)
At 5500 a motor built like yours will last virtually forever.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

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GPGoverMPG
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Re: Finding the right scale.

Post #3 by GPGoverMPG » Fri Dec 15, 2017 7:07 am

By entire set do you mean, piston set plus rod and bearings? This is also done after resizing and inserting new ARP rod bolts, right? I have pay'ed to have this work done before now i have more time that money. This will not be the only motor I do this to so equipment purchases won't go to waste on a one and done. I get the pan balance what kind of rig do you use to check big and little rod end weights. WVs for dummies has you drill holes in a ruler and use string to do it (great book for VWs and funny). So I can get the crank ground and balanced while my slow butt does the weights on the reciprocating parts. Anything outside the norm i should be doing to the block before the machine shop gets their hands on it? I'm going to paint the inside with Glyptal like my other motors to help oil return just wondering if there is something special i need to pay attention to. Thanks again
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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THE FRENCHTOWN FLYER
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Re: Finding the right scale.

Post #4 by THE FRENCHTOWN FLYER » Fri Dec 15, 2017 8:34 am

I use an Ohaus Harvard Trip Scale and a smaller 500g no-name postal scale.
Crank balancing includes the weight of bearings and rings, although those have a miniscule variance part-to-part. I have my crankshafts balanced by a machine shop. There are simple checking stands you can make, some of which use micro ball bearings to check rod end weights. I'll bet the internet has plans on there somewhere.

As far as block prep, I start by filing all sharp corners and edges on all the mounting surfaces.

Grind off all the casting flash inside and out especially around all the cam and main bearing bulkheads, paying attention to the direction of the grinding path so as not to introduce stress risers.

Grind down and sand the outside surfaces with a tootsie roll in a die grinder.

If you are into weight reduction cut off all the unnecessary bosses and protuberances not needed.

Run a bottoming tap down all the threaded holes.

Chamfer all oil drain-back holes in the lifter gallery and the oil feed hole coming from the pump and from the oil filter boss, but be careful as the pump flange does not cover the feed hole by much.

After all machining has been performed wash off the block with Simple Green or Dawn and power wash the block with high pressure. Blow dry immediately. Wipe the bores down with WD-40 or other rust inhibitor.

Paint the now-smoothed outside of the block your choice of colors (One of these days I am going to use my artistic skills and paint murals on the outside of an engine block - I've never seen that done, lol) I leave the insides unpainted, except I paint the lifter area with Glyptal.
FORD 300 INLINE SIX - THE BEST KEPT SECRET IN DRAG RACING

jason832
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Re: Finding the right scale.

Post #5 by jason832 » Fri Dec 15, 2017 8:51 am

I bought h519p stock bore pistons a few months ago. They came in one box labeled as weight matched already. If you decide to go with ARP rod bolts have the rods resized after the bolts are put in. If using ARP main studs you'll probably want the mains honed as well.

arse_sidewards
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Re: Finding the right scale.

Post #6 by arse_sidewards » Fri Dec 15, 2017 9:35 am

Shove a flywheel style alternator (off moped or side by side or any other small engine without a belt drive) inside the water pump pulley or buy one of these.
1994 F150 4x4 8ft, engine is basically stock.

66" leafs, extended radius arms, lockers in both ends, nothing special.

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Re: Finding the right scale.

Post #7 by CNC-Dude » Fri Dec 15, 2017 9:57 am

Inline cranks aren't balanced using bobweights, so it doesn't matter what your rod and piston weights are because they don't affect the crank balance in any way. The only importance is that the total combined weight of the pistons, rods, wrist pins, etc...weigh the same per cylinder.
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Re: Finding the right scale.

Post #8 by Wesman07 » Fri Dec 15, 2017 11:55 am

Great info!
In-lines we trust

86 f150 300 efi with advanced stock cam. Np435, Dana 60/ 10.25, 35" BFG's, four link front suspension with 12" travel fox coil overs, custom deaver leaf pack in the rear.

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GPGoverMPG
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Re: Finding the right scale.

Post #9 by GPGoverMPG » Mon Dec 18, 2017 7:40 am

Going to purchase Ohaus scale. Cleaning and grinding the block is one of those things that eat up time. Should be perfect as I have time while being cash impaired. It seems like bob weight would still be important as they could remove material from the counter weights for lighter assemblies. Just thinking about it. Thanks for the info
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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Re: Finding the right scale.

Post #10 by CNC-Dude » Mon Dec 18, 2017 10:00 am

You're just not understanding how balancing an inline works and are confusing processes that are only applied to V-style engines. Bobweights are only used in V engines because those reciprocating parts like rods and piston do affect the cranks balance. In an inline those parts have no affect on the balance of the crank. Removing counterweights or knife-edging an inline crank is only compensated for by removing more material from somewhere else on the crank to counteract that. Kinda like a see saw, an equal amount of material has to be removed opposite where you just removed the original weight. Rods, pistons have no affect on the crank balance at all.
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Re: Finding the right scale.

Post #11 by MechRick » Mon Dec 18, 2017 1:45 pm

Think of a V8 as four 90 degree V twins. V twins must have counterweights to balance out.

Inline engines don't need counterweights. Fours have a bit of secondary vibration (caused by speed differences between the top half and bottom half of the piston stroke) but inline sixes balance out perfectly.

More modern inline engines use counterweights to reduce stresses between the main bearings (helpful on cast-iron cranks). The cranks themselves are neutral-balanced separate from the pistons and rods.

I bought a scale accurate to one gram, at one of the local chain electronics stores, and built an adjustable stand to hold the pin end and big ends when measuring the end weights. It's important that the rod be perfectly horizontal and the point where the stand contacts the rod and the scale contact the rod remain consistent.

I measure them end to end and total weight, trying to get accurate to one gram.
1994 F150, 4.9L/ZF 5 speed, C-Vic police driveshaft
EFI head w/mild port work, 3 angle valve job
1996 long block, stock pistons, ARP rod bolts
Stock cam, aluminum cam gear
Hedman header, full mandrel bent duals, crossover, super turbos
http://fordsix.com/forum/viewtopic.php?f=2&t=73244
Bronco II with a 2.3L swap http://fordsix.com/forum/viewtopic.php?f=13&t=72863
1988 F250 2x4, 460 ZF 5 speed.

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Re: Finding the right scale.

Post #12 by GPGoverMPG » Sun Dec 24, 2017 7:31 am

I found a speedpro h519p piston weight was 1051 grams. Man that seems heavy. Still waiting to purchase scale until Christmas shipping is over getting it from amazon they seem to have best price. Wrecking yard should have my 300 pulled I just need to go get it. Weighing the rods as discribed should work consistant in positioning each rod the same is the deal. Thanks
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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GPGoverMPG
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Re: Finding the right scale.

Post #13 by GPGoverMPG » Sun Dec 24, 2017 11:09 am

Test ability to post short clip. Guess they don't make it easy. crap
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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Re: Finding the right scale.

Post #14 by CNC-Dude » Sun Dec 24, 2017 11:43 am

GPGoverMPG wrote:I found a speedpro h519p piston weight was 1051 grams. Man that seems heavy.


They may be including the weight of the wrist pin in with that weight, since the pistons come with the wrist pins. But the crown is pretty thick and dense since its a dished piston and not a flat top style design. But you need to wait until you get the engine torn down and rough bored to verify what bore size it will make before you order pistons anyway. Same with the bearings, verify what size the crank journals will clean up to before ordering your bearings.
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Re: Finding the right scale.

Post #15 by pmuller9 » Sun Dec 24, 2017 2:37 pm

The last stock 1983 300 piston with pin that I checked weighed 819 grams.

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GPGoverMPG
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Re: Finding the right scale.

Post #16 by GPGoverMPG » Tue Dec 26, 2017 7:59 am

That 819g number is better but still seems pretty heavy. The 0-2000g scale I'm looking at should be right. Figure if I get all the weights right it should be a smooth little spiner.
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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Re: Finding the right scale.

Post #17 by pmuller9 » Tue Dec 26, 2017 8:12 am

GPGoverMPG wrote:That 819g number is better but still seems pretty heavy. The 0-2000g scale I'm looking at should be right. Figure if I get all the weights right it should be a smooth little spiner.

The stock 819 grams is for reference and your are correct, that is heavy so one would hope that an aftermarket piston with pin would weight less than 819 grams.
The stock 240 rods were 714 grams total with a rotating end of 537 and 117 at the small end. Polished, shot peened and resized with ARP rod bolts.
Autotec pistons with pins were 574 grams.

Crank was balanced without bob weights.

The block prep info from FTF is important and should take at least 4 hours with a die grinder.
You will find pockets of sand and iron mix throughout the crankcase from when the block was cast that need to be removed.
The flashing in the cam tunnel is usually very heavy and needs to be ground out.
https://www.dropbox.com/s/s6u3h61cke7kf ... 6.jpg?dl=0
The top of the main webs and every edge around the pan rails, bolt hole bosses, oil filter boss...ect.
https://www.dropbox.com/s/qjh45e9hdbtd2 ... 7.jpg?dl=0

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GPGoverMPG
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Re: Finding the right scale.

Post #18 by GPGoverMPG » Wed Dec 27, 2017 8:11 am

This motor is just for fun so I have time and cash to get it right, mostly time. My little short box pickup should be super fun in the mud. These 6's sound so cool spun up. My V6 twin turbo SHO does not sound nearly as good. Thanks for the info, I'll try to take plenty of pics and weight everything so I can share the info with others.
71 F350 4x4 Super Duty 7.3 IDI
72 F250 4x4 4speed 300 I6
72 F100 2x 428 Tri Power
2014 SHO

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