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

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.

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

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

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

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

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?

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

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....

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.

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.

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

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

Re: LS376 / 480 With 4L80E
 

say what? Are they the new larger swap headers?

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.

Re: LS376 / 480 With 4L80E
 

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

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...

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!

Re: LS376 / 480 With 4L80E
 

Well here is my latest progress.

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..

Re: LS376 / 480 With 4L80E
 

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