4L60E Flex Plate

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Erik the Awful

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Actually...no.

Before we knew it was an 880 block, my concern was that they poked some ancient engine that had been in front of a Powerglide...with the potentially incompatible flexplate thereto.

But now that we know it's an actual 350/one piece seal block; the flexplate becomes something of a mystery. Certainly, I'm not familiar with what's going on.
I was just being snarky. No worries.
 

smdk2500

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I never considered that a 4L80E would have a different flexplate than a 4L60...but I guess that makes sense.

Do the '80Es use six torque converter bolts rather than just three?
When I first read this I wondered the same thing but there are people on here that know way more then I do. So I didn't bother saying anything. I did look up torque converters and the few I looked at for a 80E use 6 bolts like you thought and the 60E has 3.
 

df2x4

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Do the '80Es use six torque converter bolts rather than just three?

Yes. Some say you can just use the three 80E converter bolts that line up with the holes in the 60E flexplate and it'll be fine, but I chose to change flexplates during the 4L80E swap in my red truck. I feel better using all the bolts.
 

PlayingWithTBI

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Just an FYI, the flex plate on my 5.7L TBI engine has 6 bolt holes but only uses 3 for my 700R4/4L60. I was just looking at it this morning and wondering why...
 

Schurkey

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the flex plate on my 5.7L TBI engine has 6 bolt holes but only uses 3 for my 700R4/4L60.
Used to be really common for flex plates to have six converter bolt holes. But they were three on a "large" bolt circle, and three on a smaller bolt circle. Only three would be used in a given application, depending on the size of the torque converter. I don't have a "good" photo of that, but I've got a bad one. (Better photos on another computer...)

Buick "Big-Block" (400, 430, 455) flex plate showing weight reduction holes, balance holes, and--if you look carefully--two sets of three torque converter bolt holes, one set of which has witness marks from being used.
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The heavy-duty flexplates--for 4L80E, and on TH400 converters behind some very few high-powered engines--have six holes on the same bolt circle.
 
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PlayingWithTBI

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But they were three on a "large" bolt circle, and three on a smaller bolt circle.
I'll have to take a picture of mine, I think they're in the same circle and, keep in mind these 87+ flex plates are "balanced' with a counter weight welded to them. At least, with my 377, I have to have an 8" 400 SBC balancer (included with the Blue Print short block) and a 350 87+ flex plate (supplied by me).
 

L31MaxExpress

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Used to be really common for flex plates to have six converter bolt holes. But they were three on a "large" bolt circle, and three on a smaller bolt circle. Only three would be used in a given application, depending on the size of the torque converter. I don't have a "good" photo of that, but I've got a bad one. (Better photos on another computer...)

Buick "Big-Block" (400, 430, 455) flex plate showing weight reduction holes, balance holes, and--if you look carefully--two sets of three torque converter bolt holes, one set of which has witness marks from being used.
You must be registered for see images attach


You must be registered for see images attach


The heavy-duty flexplates--for 4L80E, and on TH400 converters behind some very few high-powered engines--have six holes on the same bolt circle.
GM used the 6 bolt, large bolt circle on all OEM 4L80E applications. Even with an anemic 4.3L they had 6 bolts. I swapped my Express to the correct flexplate when I put the 4L85E into it.
 
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