Learn me something, please

[simpson]

What exactly do the terms often found in describing an engine overhaul, "Balanced" & "Blueprinted," mean?

 

[Guest]

You mean "teach me something", right :wink:

Try this: https://en.wikipedia.org/wiki/Engine_balance

 

[tomshobby]

Combined they mean money. Just balancing the moving parts is not nearly as expensive and, in my opinion, well worth the money. Blueprinting requires a shop that can check the alignment of cyiinder bores with rotation bores and their relationship to each other. Then remachine as needed if there is enough material to do it.
Together blueprinting and balancing would minimize vibration and resulting metal fatigue, reduce friction, and reduce flex especially in parts like the crank.
A true blueprinting is not cheap.
One more reasonable alternative might be to have the engine balanced and the crank block journals line honed and consider having cam bearings installed.
I had both blueprinting and balancing done because I want my engine to last as long as I do. Only time will tell if I did the right thing.

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Only time will tell if I did the right thing[/QUOTE]

Oh, you did the right thing. Now we just need to make sure that you last as long as the engine......

 

[simpson]

You mean "teach me something", right :wink:

Try this: https://en.wikipedia.org/wiki/Engine_balance

Yes, but I figured I needed to come across as pretty ignorant since I am about alot of this good car stuff. Thanks for being kind enough to answer my question. I just read the thread on setting static timing and am having trouble assimilating what that is all about.

 

[DrEntropy]

"Static" means the engine is not running, rather set at a specific point in its rotation (8* BTDC, for example). Then the dizzy is powered with the ignition switch and the dizzy housing rotated in the opposite direction from the way the rotor turns until the points (or other "trigger" device) ~just~ hits the breaking (triggering) point at #1 firing. A 12V test light at the coil-to-dizzy lead is all you need in the way of test equipment. Lock down the clamp and it's been "static timed".

 

[simpson]

Dr. E - Thanks for the the primer. Now I've got the picture!

 

[simpson]

tomshobby - Butttt....., the TR I-6 is supposed to be an inherently well balanced engine by virtue of its original configuration, no? I mean, from what little I understand about engines and physics the straight 6 is a "natural" so to speak. I guess the stock configuration leaves room for improvement or else the effort and expense in balancing and blueprinting would not be undertaken. Especially since these powerplants are now 32+ years old - is it because of the wear & tear they have suffered by the time we start playing with them, or just a good way to improve an already solid platform?

 

[skucera]

My grandpa explained to me that blueprinting was only important when you have to race in a series where you can only race "stock" engines, and where winners have to go through random technical inspections to ensure that engines aren't modified beyond "stock" specs. Like all production specifications, the blueprints for these engines had tolerances. "Blueprinting" was the process of modifying race engines to the most favorable end each part's tolerances to increase performance as much as possible, while remaining technically "stock." It is hugely expensive, and not worth doing if it is cheaper to simply modify an engine any way you feel like, such as by raising the compression or overboring or changing the cam or reducing exhaust back-pressure.

In contrast, balancing is much cheaper, and makes for a smoother engine.

The phrase "balanced and blueprinted" is just so traditional that folks use it without really intending to communicate what it originally meant. That's like guys who say their engine is "suped up" but there is obviously no supercharger on it... it's just a phrase that means that the engine is more powerful than when it rolled out of the factory.

Scott

 

[TR3driver]

Butttt....., the TR I-6 is supposed to be an inherently well balanced engine by virtue of its original configuration, no? I mean, from what little I understand about engines and physics the straight 6 is a "natural" so to speak.

Different issue. ANY rotating mass can be out of balance.

The stuff about in-line 6's vibrating less has to do with the motion of the pistons creating balancing forces (assuming the pistons are all equal weight, etc). You can read all about it at :
https://www.autozine.org/technical_school/engine/smooth1.htm

 

[Brosky]

I agree Randall. The key here is equal weight on the pistons and rods, which is part of the blueprinting process and when added to the balancing of all rotating parts, makes for a complete package.

Expensive, yes, but if you are doing everything else, it's a natural process.