Toyota that sloppy in engine building?

carl johansson · 12-08-2007, 12:59 AM

So we are in the process of tearing down and refreshing a 7 MGE. In the process I found out something interesting about Toyota. Each cylinder has a number stamped by it on the top of the block. 1, 2, or 3. The numbers designate the finished bore size. As the engines go down the line and after the block is measured and stamped, the assemblers find a piston with a matching number, 1, 2, or 3, and puts that in the hole.

That's correct what you're thinking, the holes can all be different sizes. We happen to have 5 stamped number 2 and one stamped #1. They do something similar with the rod and main bearings. So much for Japanese precision. Apparently boring 6 holes the same size to a relatively loose tolerance is more than they can handle.

Why does Toyota do this? Do US manufacturers have the same issues with boring a block with precision? if so - do they just ignore the slop, or are they just better at boring more precisely?

This is our first import - so we are learning as we go!

Carl Johansson

suprra_girl · 12-10-2007, 09:36 AM

yep that is what they do but the size difference will be absolutely minimal but generally once you tear an engine down your recondition will hone/bore (depending on what you're doing) so they should be even.

As to the reason, i have no idea, just know that they do lol

12-10-2007, 09:36 AM	#2
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	yep that is what they do but the size difference will be absolutely minimal but generally once you tear an engine down your recondition will hone/bore (depending on what you're doing) so they should be even. As to the reason, i have no idea, just know that they do lol __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

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12-08-2007, 12:59 AM	#1
carl johansson 3" Exhaust Join Date: Nov 2007 Location: Auberry, California Posts: 141	Toyota that sloppy in engine building? So we are in the process of tearing down and refreshing a 7 MGE. In the process I found out something interesting about Toyota. Each cylinder has a number stamped by it on the top of the block. 1, 2, or 3. The numbers designate the finished bore size. As the engines go down the line and after the block is measured and stamped, the assemblers find a piston with a matching number, 1, 2, or 3, and puts that in the hole. That's correct what you're thinking, the holes can all be different sizes. We happen to have 5 stamped number 2 and one stamped #1. They do something similar with the rod and main bearings. So much for Japanese precision. Apparently boring 6 holes the same size to a relatively loose tolerance is more than they can handle. Why does Toyota do this? Do US manufacturers have the same issues with boring a block with precision? if so - do they just ignore the slop, or are they just better at boring more precisely? This is our first import - so we are learning as we go! Carl Johansson Last edited by carl johansson; 12-08-2007 at 01:01 AM.