LS376 / 480 With 4L80E - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BigShoe24 · 02-04-2011, 08:28 PM

Hey Guys,

Just got my LS376 in, and already have the 4L80E in the truck. I went to install the GM p/t #12602448 flex plate to my torque converter and it didn't quite match up. The holes on the flex plate are about a 1/8 to 1/4 of an inch in from lining up.

Any idea of how to proceed? Should I get a different flex plate or would it be possible to 'open' the holes up in order to for both pieces to line up?

Thanks

blazerboy72 · 02-04-2011, 09:06 PM

You can open them up as long as the crankshaft to torque converter spacing is right. All of the 4l80e flex plates I have seen are 6 bolt you may want to double check.

cableguy0 · 02-04-2011, 09:13 PM

Its the wrong flex plate for a 4l80e. A 4l80e has 6 bolts.

clinebarger · 02-04-2011, 09:13 PM

The holes not lining is not the real problem, The "snout" on the 4L80E converter is not long enough to engage into the crankshaft.

This is what GM uses to mate a 4L80E to a LS engine http://www.gmpartsdirect.com/results...umber=12621399 & the only Flexplate that I know of that will work with your 6-bolt converter

Heres another thread on the subject http://67-72chevytrucks.com/vboard/s...d.php?t=426994

BigShoe24 · 02-05-2011, 11:55 AM

Thanks guys, I'll post pics of the motor and install once I get the new plate and spacer.

BigShoe24 · 02-06-2011, 12:16 AM

So I pulled the flex plate that came on the motor. It matched the one sold to me that I was told would bolt right up to the 4L80E, go figure. Hopefully the GM dealer will be a nice guy and swap me out for this one; GM part number 12621399

BigShoe24 · 02-09-2011, 11:25 PM

Got my flex plate in and looks good.... I need to grab some more bolts tomorrow to bolt up the converter though. Do you guys recommend using washers, lock washers, or just loctite? Also, the GM specs recommend bolting the flex plate to crank at 74 ft/lbs. Does that sound right to everyone?

clinebarger · 02-10-2011, 06:20 PM

You need the correct torque converter bolts, New ones will have threadlocker already applied to them, Like these http://www.autozone.com/autozone/acc...er=732339_0_0_

Torque converter bolt torque is 32 ft. lbs

74 ft. lbs. is the final torque on the flexplate bolts, Heres the entire procedure.
First Pass...20 Nm (15 ft. lbs.)
Second Pass...50 Nm (37 ft. lbs.)
Final Pass...100 Nm (74 ft. lbs.)
Be sure to apply thread sealant to them, I use this http://www.permatex.com/products/aut...ad_Sealant.htm

BigShoe24 · 02-12-2011, 01:23 PM

clinebarger, thanks bud. When I was doing final pass I started to turn the motor over. I suppose I should place a bar stop through the fly wheel to tighten. I really hate to over tighten these bolts into the crank though. Any words of wisdom....

BigShoe24 · 02-13-2011, 08:10 PM

Motor fits very well. Installed converter then dropped in the motor. Once all the bolts were nice and snug I went to go bolt up the converter to the flex plate. When I checked it out it had perfect clearance, about a 1/16". Hopefully I can get some headers picked out soon. I will be ordering the Concept One accessory set, and a computer from Speartech very soon.

Any word on the Doug Thorley "big tube" headers. From what I've read I should try to run at least a 1 & 5/8" header.

shrunken66stroker · 02-21-2011, 12:28 AM

I assume you have L92 or LS3 heads on there. I don't know the cam specs but to pump out 480hp out of 376ci it's probably got a lot of lift and duration. Most people making that kind of power are running headers with at least 1 3/4" primaries and 3" collectors. I think any smaller and you'll be choking off horsepower. Doug Thorley has been talking about making some swap headers with larger primaries using the 324y for a template, but I haven't seen them yet. They're supposedly in the prototype/testing phase. There's a thread on it here with someone from DT talking about it. Dynatech swap headers for 70-81 camaros are being used and they're around $400 coated. They hang down a few inches below the frame but other than that I can't see any drawbacks. Good luck with your swap.

shrunken66stroker · 02-21-2011, 12:30 AM

http://67-72chevytrucks.com/vboard/s...d.php?t=445414

BigShoe24 · 11-19-2011, 11:13 PM

Hey guys, anyone have any insight or suggestions on what accessory drive kit to run? I am trying to decide between Concept One and Billet Specialties Tru Trac. Also, if there are any other products I'm always open ears. Thanks

mcmlxix · 11-22-2011, 03:15 AM

Quote:

Originally Posted by BigShoe24

Hey guys, anyone have any insight or suggestions on what accessory drive kit to run? I am trying to decide between Concept One and Billet Specialties Tru Trac. Also, if there are any other products I'm always open ears. Thanks

Try looking at these guys... I have LS376/480 for my Chevelle, this is the kit I was going to run... in black with all the accessories....

http://s41657.storefront-solutions.c...?CategoryID=38

BigShoe24 · 02-03-2012, 07:48 PM

Got some new hardware today. Hopefully will get them on tomorrow.

usmcchevy · 02-03-2012, 11:23 PM

Wow, those are purdy! Sure look more beefy than the smaller DT's too.

BigShoe24 · 02-04-2012, 06:51 PM

They are beefy and they DON'T fit. To bad...

HavinSomeFun · 02-04-2012, 07:12 PM

Quote:

Originally Posted by BigShoe24

They are beefy and they DON'T fit. To bad...

say what? Are they the new larger swap headers?

BigShoe24 · 02-04-2012, 10:46 PM

Yep. The right side (when sitting in the truck) hit in the rear; on the firewall. I have a Porterbuilt Dropmember which moves the motor back. I really thought they'd fit.

usmcchevy · 02-04-2012, 11:46 PM

Quote:

Originally Posted by BigShoe24

Yep. The right side (when sitting in the truck) hit in the rear; on the firewall. I have a Porterbuilt Dropmember which moves the motor back. I really thought they'd fit.

Sorry to hear that. Does the dropmember just move the motor back or back and up?

BigShoe24 · 02-04-2012, 11:49 PM

Back and Up. Now that I'm looking at the headers; the rear passenger tube goes way back when it should just go down and flow like the driver side. Oh well...

68GMCCustom · 02-05-2012, 02:04 AM

looks like that #6 tucking behind #8 adds a couple inches. The Dynatech's don't do that.

and I'd think you need at least a 1 3/4" primary or even 1 7/8", w/3" collector or larger. I've even started seeing LSx headers with big block sized 2" primaries!

BigShoe24 · 02-18-2012, 06:32 PM

Well here is my latest progress.

mooseknuckles · 02-18-2012, 07:56 PM

awesome!...I'm ordering me a set of those to try...they're $300 cheaper than the hookers and the quality looks good too..

BigShoe24 · 02-18-2012, 08:09 PM

Great quality. I'm very happy with the fit as well.

02-04-2011, 09:06 PM	#2
blazerboy72 Senior Member Join Date: Mar 2002 Location: Temple, Ga Posts: 854	Re: LS376 / 480 With 4L80E You can open them up as long as the crankshaft to torque converter spacing is right. All of the 4l80e flex plates I have seen are 6 bolt you may want to double check.

02-04-2011, 09:13 PM	#3
cableguy0 Senior Member Join Date: Apr 2000 Location: Delta,Pa Posts: 14,948	Re: LS376 / 480 With 4L80E Its the wrong flex plate for a 4l80e. A 4l80e has 6 bolts. __________________ Owner of North Point Car Care in Dundalk Md. We specialize in custom exhaust on both modern and classic vehicles. We are a full service auto shop from classics to modern vehicles. Feel free to contact me with questions. I will give a 10% discount to any board member.

02-04-2011, 09:13 PM	#4
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: LS376 / 480 With 4L80E The holes not lining is not the real problem, The "snout" on the 4L80E converter is not long enough to engage into the crankshaft. This is what GM uses to mate a 4L80E to a LS engine http://www.gmpartsdirect.com/results...umber=12621399 & the only Flexplate that I know of that will work with your 6-bolt converter Heres another thread on the subject http://67-72chevytrucks.com/vboard/s...d.php?t=426994 Last edited by clinebarger; 02-21-2011 at 12:44 AM.

02-05-2011, 11:55 AM	#5
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Thanks guys, I'll post pics of the motor and install once I get the new plate and spacer. __________________ RCC

02-09-2011, 11:25 PM	#7
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Got my flex plate in and looks good.... I need to grab some more bolts tomorrow to bolt up the converter though. Do you guys recommend using washers, lock washers, or just loctite? Also, the GM specs recommend bolting the flex plate to crank at 74 ft/lbs. Does that sound right to everyone? Attached Images __________________ RCC

02-04-2011, 08:28 PM	#1
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	LS376 / 480 With 4L80E Hey Guys, Just got my LS376 in, and already have the 4L80E in the truck. I went to install the GM p/t #12602448 flex plate to my torque converter and it didn't quite match up. The holes on the flex plate are about a 1/8 to 1/4 of an inch in from lining up. Any idea of how to proceed? Should I get a different flex plate or would it be possible to 'open' the holes up in order to for both pieces to line up? Thanks Attached Images __________________ RCC

02-06-2011, 12:16 AM	#6
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E So I pulled the flex plate that came on the motor. It matched the one sold to me that I was told would bolt right up to the 4L80E, go figure. Hopefully the GM dealer will be a nice guy and swap me out for this one; GM part number 12621399 Attached Images __________________ RCC

02-10-2011, 06:20 PM	#8
clinebarger Senior Member Join Date: May 2009 Location: Fort Worth, TX Posts: 6,370	Re: LS376 / 480 With 4L80E You need the correct torque converter bolts, New ones will have threadlocker already applied to them, Like these http://www.autozone.com/autozone/acc...er=732339_0_0_ Torque converter bolt torque is 32 ft. lbs 74 ft. lbs. is the final torque on the flexplate bolts, Heres the entire procedure. First Pass...20 Nm (15 ft. lbs.) Second Pass...50 Nm (37 ft. lbs.) Final Pass...100 Nm (74 ft. lbs.) Be sure to apply thread sealant to them, I use this http://www.permatex.com/products/aut...ad_Sealant.htm Last edited by clinebarger; 02-13-2011 at 09:28 PM.

02-12-2011, 01:23 PM	#9
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E clinebarger, thanks bud. When I was doing final pass I started to turn the motor over. I suppose I should place a bar stop through the fly wheel to tighten. I really hate to over tighten these bolts into the crank though. Any words of wisdom.... __________________ RCC

02-13-2011, 08:10 PM	#10
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Motor fits very well. Installed converter then dropped in the motor. Once all the bolts were nice and snug I went to go bolt up the converter to the flex plate. When I checked it out it had perfect clearance, about a 1/16". Hopefully I can get some headers picked out soon. I will be ordering the Concept One accessory set, and a computer from Speartech very soon. Any word on the Doug Thorley "big tube" headers. From what I've read I should try to run at least a 1 & 5/8" header. Attached Images __________________ RCC

02-21-2011, 12:28 AM	#11
shrunken66stroker Registered User Join Date: Jan 2008 Location: Las Vegas, Nv Posts: 954	Re: LS376 / 480 With 4L80E I assume you have L92 or LS3 heads on there. I don't know the cam specs but to pump out 480hp out of 376ci it's probably got a lot of lift and duration. Most people making that kind of power are running headers with at least 1 3/4" primaries and 3" collectors. I think any smaller and you'll be choking off horsepower. Doug Thorley has been talking about making some swap headers with larger primaries using the 324y for a template, but I haven't seen them yet. They're supposedly in the prototype/testing phase. There's a thread on it here with someone from DT talking about it. Dynatech swap headers for 70-81 camaros are being used and they're around $400 coated. They hang down a few inches below the frame but other than that I can't see any drawbacks. Good luck with your swap. __________________ http://67-72chevytrucks.com/vboard/s...54#post3194654

02-21-2011, 12:30 AM	#12
shrunken66stroker Registered User Join Date: Jan 2008 Location: Las Vegas, Nv Posts: 954	Re: LS376 / 480 With 4L80E http://67-72chevytrucks.com/vboard/s...d.php?t=445414 __________________ http://67-72chevytrucks.com/vboard/s...54#post3194654

11-19-2011, 11:13 PM	#13
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Hey guys, anyone have any insight or suggestions on what accessory drive kit to run? I am trying to decide between Concept One and Billet Specialties Tru Trac. Also, if there are any other products I'm always open ears. Thanks __________________ RCC

02-03-2012, 07:48 PM	#15
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Got some new hardware today. Hopefully will get them on tomorrow. Attached Images __________________ RCC

02-03-2012, 11:23 PM	#16
usmcchevy Has more rust than truck... Join Date: Apr 2005 Location: Ivanhoe, MN Posts: 2,421	Re: LS376 / 480 With 4L80E Wow, those are purdy! Sure look more beefy than the smaller DT's too. __________________ 1972 Custom/10 SWB, 4.8/4l80e Build thread LSx Swap FAQ index



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02-04-2012, 06:51 PM	#17
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E They are beefy and they DON'T fit. To bad... __________________ RCC

02-04-2012, 10:46 PM	#19
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Yep. The right side (when sitting in the truck) hit in the rear; on the firewall. I have a Porterbuilt Dropmember which moves the motor back. I really thought they'd fit. __________________ RCC

02-04-2012, 11:49 PM	#21
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Back and Up. Now that I'm looking at the headers; the rear passenger tube goes way back when it should just go down and flow like the driver side. Oh well... __________________ RCC

02-05-2012, 02:04 AM	#22
68GMCCustom Truck and auto performance nut Join Date: Feb 2007 Location: McKinney,Texas Posts: 3,848	Re: LS376 / 480 With 4L80E looks like that #6 tucking behind #8 adds a couple inches. The Dynatech's don't do that. and I'd think you need at least a 1 3/4" primary or even 1 7/8", w/3" collector or larger. I've even started seeing LSx headers with big block sized 2" primaries! __________________ Kurt - '68 GMC short step - NIB '09 LY6 6.0L crate motor w/mods, NIB '12 crate 4L85e w/billet 3k stall Circle D, 3.73 posi 12 bolt, DynaTech f-swap headers, 3/4 drop, handling mods, etc. - my toy '72 Chevy LWB C-10 Highlander - 350/350 ps/pb/tilt/ac - not original but close '06 Chevy TrailBlazerSS - LS2/4L70e - little black hot rod SUV - my DD '18 Kia Sorento - wife's econo-driver '95 Chevy S10 - reg cab shortbed, LS, 4.3, auto... my '68's powertrain and chassis build -links broken A surprise phase - carb to efi -links broken

02-18-2012, 06:32 PM	#23
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Well here is my latest progress. Attached Images __________________ RCC

02-18-2012, 07:56 PM	#24
mooseknuckles Registered User Join Date: Sep 2009 Location: ottawa,canada Posts: 4,550	Re: LS376 / 480 With 4L80E awesome!...I'm ordering me a set of those to try...they're $300 cheaper than the hookers and the quality looks good too.. __________________ my build threads '86 C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415628 '67 C10 http://67-72chevytrucks.com/vboard/s...d.php?t=635078 '63 GMC http://67-72chevytrucks.com/vboard/s...d.php?t=674682

02-18-2012, 08:09 PM	#25
BigShoe24 True Addiction Join Date: Nov 2005 Location: FTL Posts: 415	Re: LS376 / 480 With 4L80E Great quality. I'm very happy with the fit as well. __________________ RCC

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