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LSX376-B15 Rear Engine Cover Question?

3K views 5 replies 3 participants last post by  kittyboy 
#1 · (Edited)
Recently I replaced the clutch on my LSX376-B15 engine. I took the opportunity to also replace the stock oil restrictor galley plug with an Improved Racing billet design. The diameter of the IR plug is 5mm, 1mm less than the stock 6mm, 15% difference. I also replaced the rear engine main seal. After removing the rear engine cover I was surprised to learn the B15 does not use a standard LS rear cover gasket! The correct replacement are two o-rings that thread into channels cut into the cover plate. My question is: Why the different design?
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#2 ·
1. With the creation of the LSX iron block, GM was shooting specifically for the aftermarket builder/racer market rather that production cars. Among their many changes made for the racer market were priority main oiling, more 'meat' around the cam bearings, lifters, plus windows in the lifter galley (for 6-bolt access) and a straight cam bore.
2. The redesign of the oil galleys created required different end plates because the galley holes are larger and in different locations compared to production LS blocks. (LSx blocks)
3. both the rear cover and the front cam retainer plate are different and special to the LSX block
4. I think they utilized the spaghetti gasket because it is easy to just have a roll of the stuff in the trailer rather than buying bespoke LSX-only special (likely expensive) gaskets.
 
#3 ·
1. With the creation of the LSX iron block, GM was shooting specifically for the aftermarket builder/racer market rather that production cars. Among their many changes made for the racer market were priority main oiling, more 'meat' around the cam bearings, lifters, plus windows in the lifter galley (for 6-bolt access) and a straight cam bore.
2. The redesign of the oil galleys created required different end plates because the galley holes are larger and in different locations compared to production LS blocks. (LSx blocks)
3. both the rear cover and the front cam retainer plate are different and special to the LSX block
4. I think they utilized the spaghetti gasket because it is easy to just have a roll of the stuff in the trailer rather than buying bespoke LSX-only special (likely expensive) gaskets.
When I inserted the o-ring in the shallow groves, my concern was that it could easily mis-locate out from the grove during cover install, no way to verify once the plate is installed. At least with a gasket there's not the same worry. I used a small amount of Permatex in a few locations to help maintain the position of o-ring for that reason. Hopefully no surprises.
 
#4 · (Edited)
My preference is the spaghetti string over bespoke gaskets for this sort of application. Imagine how hard to find and pricey the gaskets would be since they don't fit production engines. And... most folks would just use a big ol' bead of silicone anyway.
Install method I use is just a small amount of RTV Silicone along the groove (no build-up, just the slightest 'film') and lay the spaghetti in, turn the cover over to make certain the spaghetti is stuck and go..
 
#6 · (Edited)
It's installed, haven't ran the engine yet, hopefully it didn't pop out the channel during install. Just seems to be more risky using an o-ring vs a gasket for this reason. Couldn't find the OEM torque specs, so I went with Grade8 5/16" lubricated at 18.5lbs. Lubricated because installed using blue Loctite.

My other concern has to do with the oil pan gasket being disturbed during cover removal. I did prepared the corner cover gap locations by removing the previously applied sealant, solvent cleaning, then reapplied fresh sealant in those places. Took a chance not replacing the oil pan gasket. Hopefully the oil pan gasket will compress properly and not leak. The oil pan gasket was new 6k ago, less than a year, see how that turns out. As I'm sure you know, pan gaskets are not an easy 15 minute R&R on V2s.

Installed an Improved Racing barbell and new rear crank seal.
 
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