Balance plates. Who's right, Who's wrong

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Max1196

Max1196

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What we have is a 1 on 1 comparison between the SFI approved B&M 10236 plate for the back of a 360 crank and neutral balanced torque convertor. Up next is the Quick times QTMRM-531 for use with a neutral balanced flywheel used with a 360 crank. Balance results show one of these isn't quite like the other. By about 20 grams. Crank is balanced now for use with the automatic BUT I wanted to see how this stuff compared. Tested each plate attached to the crank individually and then mounted the 2 plates clocked 180* to see what that would net, if they were identical, they should have canceled each off-set to become "neutral". Not so, they were still out by about 20 grams to each other. FYI the QTM would need weight removed by 20 g's at the indicated jiffy mark.

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So which is actually closer to the "standard" LA 360 balance?
Your test shows they do not equal or offset each other by about 20 grams, but which is really off? Is the QT heavy by 20, or is the B&M light by 20? Or are they both off, and the cumulative difference is 20g?
Inquiring minds want to know...
 
It doesn't matter. Choose one and have it all balanced together. Problem solved.
 
Well, if you're going to have an entire rotating assembly balanced, you won't need adapter weights...
This question is to benefit the guy who just wants to slap a 360 in front of a 904 (or whatever) and go.
 
Professor Fate said:
Well, if you're going to have an entire rotating assembly balanced, you won't need adapter weights...
This is to benefit the guy who just wants to slap a 360 in front of a 904 (or whatever) and go.
Click to expand...
I know. From the sound of it, he already had it balanced without the weight. Maybe I misread it. If it was mine, I'd have it all balanced to match the external balancer along with whichever of the plates I chose. That'd be the most economical way. Otherwise, it's tons of mallory metal to make it a neutral balanced motor.
 
the cutout on the flexplate and the 'weight' on the balance plate are not in line with the bolt pattern so you can't flip the weight 180 degrees on the bolts and expect it to be balanced still. if there were 2 (opposite) bolt holes at 90 degrees to the centre of the weight yes it'd be a relevant comparison, but with the bolt spacing as they are you can't do that. hopefully that makes sense.
neil.
 
I just noticed the BM is for a converter and the QTM is for a flywheel. I gotta say I wouldn't imagine that these 2 products would cancel each other out. It'd be more interesting to see if they actually balanced the application they were intended for. But thanks for the info none the less.
 
I have use the balanced B&M SFI flex plates on both a 340 and 360 cast crank motors for street and strip and had absolutely no vibration issues at all.
And yes I have all of my COMPLETE assemblies balanced during the machine work.
Why would anyone NOT do this?
 
mygasser said:
hopefully that makes sense.
Click to expand...
I knew someone would try this angle, but NO it is not "flipped" it is rotated 180*, other than the off-set bolt holes it IS still 180* rotated. If this still confuses you, disregard the direct comparison and focus on the fact that each plate was mounted on the crank individually and produced 2 different balance results, the objective is both should have produced identical results, to the tune of 19.79 in.-oz. factory spec, so once again, which one is more accurate to oem spec.
Professor Fate said:
and the cumulative difference is 20g?
Click to expand...
Good word choice, maybe both are not right.
 
Max1196 said:
I knew someone would try this angle, but NO it is not "flipped" it is rotated 180*, other than the off-set bolt holes it IS still 180* rotated. If this still confuses you, disregard the direct comparison and focus on the fact that each plate was mounted on the crank individually and produced 2 different balance results, the objective is both should have produced identical results, to the tune of 19.79 in.-oz. factory spec, so once again, which one is more accurate to oem spec.

Good word choice, maybe both are not right.
Click to expand...
my mistake on the choice of the word flip. i did mean rotated. but as i meant if a 90 deg t is drawn through the 2 bolts 'either side' of the weight/cutout and up through the weight/cutout the 'upright of the t is not centred on said weight/cutout. meaning the centre of the weight/cutout is at roughly 1 o clock in relation the the bolt holes. i was just saying rotating one 180 deg wouldn't cancel the imbalance not that you were wrong about them not being balanced accurately.
i hope that makes sense this time :thumbsup:
 
Have the Quick Time RM-531 balance plate on the stock build 360 with a Neutral Balance stock 318 flywheel.

Set up on the engine run stand, testing various 2 barrel and 4 barrel carburetors, also testing points distributor, mopar electronic ignitions, and mopar HEI conversions with the E-coils.

All tests running smooth, no out of balance vibrations.

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Running up at 1500 rpm, running smooth as seen by the crisp clear 2 barrel carburetor pictured. If it was out of balance and vibrating that carb picture would be showing blurred.

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Stock neutral balance flywheel makes a simple setup to run the starter to with a stock 318 bell housing on the engine run stand.

One thing to recommend is 1/8" longer flywheel mount bolts to run with the Quick Time balance plate. Tucks in real nice on the back side of the flywheel, starter engages well.

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☆☆☆☆☆
 
Not to mention, you are missing 2 of the bolts due to the holes not lining up, that will effect the ballance also, as the holes are not symmetrical. And the other thing is, the factory ballance job can be off quite a bit from what we can achieve these days.
 
each plate was mounted on the crank individually and produced 2 different balance results, the objective is both should have produced identical results
Click to expand...

Good info.

What I’d do is balance the crank with whichever plate would suit the immediate need(auto or std).
Then modify the other plate(if possible) to duplicate the imbalance of the first one.

Quick thought……..is one of them for a Magnum?
 
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PRH said:
Good info.

What I’d do is balance the crank with whichever plate would suit the immediate need(auto or std).
Then modify the other plate(if possible) to duplicate the imbalance of the first one.

Quick thought……..is one of them for a Magnum?
Click to expand...
I shouldn’t be. The 5.9 Magnum is about four ounce-in. less offset than a 360 LA. So I think he is right, it’s a difference in manufactured parts here.
But then again, I have never run a balancer for testing any of this stuff. Just theory.
 
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