[4k] The merits of Plastigage? ...A Jafromobile "short"

READ THIS! Plastigauge is marketed to the general public. It's been used for decades and saved millions of people thousands of dollars on precision tools and costly mistakes. It costs 1 hundredth of the cost of the precision tools. It visually show you how your parts are all fitting. It goes where precision tools don't fit. I don't have a negative opinion of it. I own precision tools yet you still see me use it in my videos. Why?

For most non-professionals, it's fine as their bare minimum means measurement. Freshening up a well used engine with a new set of bearings using the same parts as before likely will give you fairly accurate results. There's also those $150 junkyard engines that you can't justify buying a thousand dollars worth of precision measurement tools for. $5 is easier to justify. It has its place. It yields enough information to tell you whether the thing fits in a hole, but it doesn't measure oil clearances. It only "checks" them.

When you get into the high performance realm of engine building, that's when you need precision tools because the parts are expensive, and therefore; so too are your mistakes. Aftermarket parts don't fit like the parts in an engine that you're rebuilding back into stock form do. Performance engines are typically set up on the looser side, and race engines are typically set up on the razor's edge of serviceable limits. They're spun faster, achieve higher pressures, loads, temperatures and rates of thermal expansion. Those engines also tend to have a harder time making oil pressure as a result, especially when they're cold... and they wear out faster as a result. These are the situations where scrutinizing tenths of thousandths of an inch variations in oil clearances matter a whole lot more, and Plastigauge will never give you anything close to that degree of accuracy. But some professionals still use it. Again, why?

While I passed the plastigauge test in the previous video (if I were building a stock engine), I demonstrate how in order to get useful information from it, you must have already done your precision measurements. You watch my videos, so you know I have all that measurement stuff figured out already. Multiple times. If you're working with a machinist, they can get these numbers FOR YOU. If you're simply skimping on the expense of precision tools and solely relying on plastigauge for your results, then there's a lot that Plastigauge does not tell you.

I had already determined what parts I needed for assembly, and when I attempted to use that combination, it failed. The math said it should have worked. It didn't. When I attempted to use the combo that shouldn't have worked, it passed in flying colors. This video is the result of the complete findings and it demonstrates well why you can't take plastigauge result seriously.

Fortunately for those using a bearing girdle to bolster their mains, I demonstrate a means of measurement to help you verify whether or not the will fit properly, and discuss one method for how to address it. The Kiggly bearing girdle is a dynamite product. My machinists are dynamite people. I may be a bit overzealous at times trying to resurrect old parts and make them famous. This engine block is no exception to that. It's been through a lot even before I found it, apparently.

Building engines is never about finding fault anywhere. It's about what do you have?... what do you want?... how are you going to get it there? I said 2 videos ago, "You can take every means necessary to ensure precision and you're lucky if you're only off by a half thousandth somewhere." A job well done means you've used every means available to you to check your work.

If you want to follow me on Patreon and support my production, please visit www.patreon.com/jafromobile for private discussions and additional content. Those patrons are the reason why I'm able to do this, and why it's still here after 11 years. I have some big news coming for everyone soon, and it will also benefit my Patreons first/the most. That's a spoiler of sorts. You'll figure it out soon enough.

Also for the bearing girdle crowd, here's Kiggly's instructions for your installation:
https://bd2676c2-1d1a-42eb-b758-7f846...

My advice is to follow those instructions. I've got many of their parts going into my build. You've seen them. They make some amazing stuff for the 4g crowd, and therefore a better community overall. Let me be your example of what not to do, or at least how to avoid it. My situation is unusual, but totally fixable.