Are These Rods Good?

[TobyB]

...and a .001 graduated mic can feel the difference of .0001 in the crank, certainly...

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[LJ851]

M20 connecting rod specifications run out to 4 decimal places in the Bentley (with a tolerance of +/- .0002 being common), are you saying you can just throw out the last decimal for all rebuild/tolerance checking procedures? If that's true, it's news to me.

You don't throw out the fourth decimal place (in inches), it's just that ONE tenth is not really going to make a difference. A few tenths, yes in a few select parts on an engine. Crank journal taper and roundness for example.

[AndrewBird]

A dial or micrometer bore gauge can measure down to tenths no problem. Some can even measure down to .00001, but those are rarer and more specialized.

Pretty much any bore for a bearing will have at least a +/- .0005 tolerance. All depends on the application.

[EatsHondas]

i've heard of guys measuring to a tenth for bearings on one of the HPF videos. i don't have the right equipment to know if this is realistic and repeatable in practice.

http://www.mscdirect.com/product/det...&item=57480824

Guess it depends how much you're willing to spend. But the tools are out there.

[EatsHondas]

.0001, you can't even measure that accuratley. Thermal growth from holding the mic in your hand is probably more than that.

Aircraft parts are often to .001 or maybe .0005 at most...

M20 connecting rod specifications run out to 4 decimal places in the Bentley (with a tolerance of +/- .0002 being common), are you saying you can just throw out the last decimal for all rebuild/tolerance checking procedures? If that's true, it's news to me.

[digger]

i've heard of guys measuring to a tenth for bearings on one of the HPF videos. i don't have the right equipment to know if this is realistic and repeatable in practice.

[SkiFree]

and to understand the weight of a gram in practical terms...... it's about the weight of a single sheet of copy paper.

And for the record, these rods are not balanced even close to the advertised amount. As all China parts, it's always hit or miss to start with. The only saving grace is the diligence of the middle man (I wouldn't say a ebay store middle-man is all that diligent). It took 3-4 sets to put together a decently "balanced" set.

[nando]

.0001, you can't even measure that accuratley. Thermal growth from holding the mic in your hand is probably more than that.

Aircraft parts are often to .001 or maybe .0005 at most...

[LJ851]

Precision internals are supposed to be measured to within .0001 (ten-thousandths) of an inch

LOL, one ten thousandth.

[digger]

Am I wrong?

a tenth of a gram is more than enough, any less than that and i think people are exaggerating the accuracy of the scale in a 500g part.

1 tenth is 0.1g, so this in 500g is 1 part in 5,000 or 0.02%
1 hundredth 0.01g, so this in 500g is 1 part in 50,000 or 0.002%

[EatsHondas]

hundredths of a gram lol

Am I wrong?

[digger]

Balanced within a gram? Is that supposed to be impressive? A blind kid could do that with a whetstone. Precision internals are supposed to be measured to within .0001 (ten-thousandths) of an inch and at least hundredths of a gram if not smaller. I would stay away from these rods.

hundredths of a gram lol

[EatsHondas]

Balanced within a gram? Is that supposed to be impressive? A blind kid could do that with a whetstone. Precision internals are supposed to be measured to within .0001 (ten-thousandths) of an inch and at least hundredths of a gram if not smaller. I would stay away from these rods.

[redlightpete]

the issue will be a big end / pin size accuracy on a low hp application. the material wont be the limiting factor. eta rods are alot cheaper and go with the budget theme

Try to get some with good pin bushings to avoid having to get replacemant ones sized.

[digger]

the issue will be a big end / pin size accuracy on a low hp application. the material wont be the limiting factor. eta rods are alot cheaper and go with the budget theme