Chevy engine tech? Bottom end

strange1

strange1

Well-Known Member
Joined
Mar 31, 2005
Location
Elkin
i got a 4.3 v6 a couple of years ago that was supposed to have been rebuilt. It is now time to start putting it in a truck, and I am wanting to pull the bottom end apart to inspect the bearings while it is on a stand. I'm really hoping I can take it apart, look at it, and put it right back together. My question is regarding the torque specs for the bearing caps. I have a spec of 77 ft/lbs, and a tightening pattern, for the main caps. The only consistent info I can find for the rod caps is 20 ft/lbs plus an additional 70 degrees. I do not have the tool to accurately measure the additional 70 degrees. Any advice? Preferably from someone who has successfully assembled a GM bottom end......
 
Use a digital torq wrench with angle finder....
 
If you're tight on cash and only need to do a few fasteners, you can use one of these $15 beauties with your torque wrench:

astatic.summitracing.com_global_images_prod_large_otc_4554_w.j590c0fa36414b4bf1358aca88a611af8.jpg


http://www.summitracing.com/parts/otc-4554

Snap-On makes one too, but it's $100.

apublic.snapon.com_R_RRD_Objects_lg_images_TA360.jpg


They're just an extension with a degree wheel, and a bar to hold the degree wheel in a fixed position relative to the drive extension (the needle moves with the extension).

And make sure you know whether the torque spec calls for lubricated or non-lubricated fasteners.

I've never assembled a V6 bottom end; my advice is general and still applies.
 
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It's close enough to halfway between 45 and 90 degrees. I'd just eyeball it.
 
jeepinmatt said:
It's close enough to halfway between 45 and 90 degrees. I'd just eyeball it.
Click to expand...

I had a guy that works in an engine shop text me that earlier. Said thats how they do it, and they do a lot of engines.
 
Would suggest using a paint pen to draw a line on the bolts and a breaker bar instead of a ratchet when doing this. A hex head bolt has its points at 0, 45, 135, 180, 225, and 315. Now if you make a small mark with your paint pen at the initial start point you can get it pretty much spot on.

I did use an electronic torque wrench when doing head boots a lot and a few bottom ends with TTY bolts.
 
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I've done plenty of TTY head bolts, 85 degrees on a subaru? Just shy of 90. Beauty of TTY is that if you go 78 degrees it's the same torque as 75 degrees. The bolt stretches when you go so many degrees, which is why bolt replacement is typically recommended in such applications.
 
iwaxmyjimmy said:
Would suggest using a paint pen to draw a line on the bolts and a breaker bar instead of a ratchet when doing this. A hex head bolt has its points at 0, 45, 135, 180, 225, and 315.
Click to expand...
That would be a funny looking bolt that required a special socket. The points are actually at 0, 60, 120, 180, 240, and 300 degrees.
 
You forgot the point at 360 degrees. Oh, wait a minute.
 
jeepinmatt said:
That would be a funny looking bolt that required a special socket. The points are actually at 0, 60, 120, 180, 240, and 300 degrees.
Click to expand...


Yeah something like that lol my bad
 
Armed with the knowledge that the 6 points on a socket are 60 degrees apart, I can use a sharpie and a little math to mark a socket at 0 and approximately 70 degrees. Put another mark on a stationary surface and eyeball it.

However, my plans for a quick inspection and put it all back together have hit a snag.

image.jpg
 
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