LS3 Aluminum, 6 Bolt Main, 4.067" Bore
Manley forged dish pistons 4.065", -2cc
Callies CompStar 4.00" stroke, forged crank
Callies CompStar forged Connecting H beam Rods, 6.125" length, 2.100" crank pin, .927 wrist pin, (Includes ARP 2000 Series Connecting Rod Bolts).
L92 heads, milled 0.030, 65 CC chamber
LS3 GM MLS 0.051" gasket, bore diameter 4.100"
Comp 921 spring kit
Comp Cam 230 XFI / 242 XER, 114 LSA
Ported LS3 intake
Manley hardened 7.35" pushrods
Ackerly & Childs NOS/Boost rings 1/16 - 1/16 - 3/16
Clevite "H" series race rod and main bearings
Durabond cam bearings

I have suffered from oil consumption since the 416 was installed.

- Aggressive driving consumes 1 qt per ~250 miles.
- Highway driving yields little to no oil consumption.
- Engine break-in down with break in oil. Oil used since is high in ZDDP.
- I do not believe it is the PCV system as I have tried two different catch cans (one being a vent-to-atmosphere type) and many different PCV routing setups. The various catch cans and PCV routing has had little-to-no effect on the oil consumption. With the vent-to-atmosphere setup I have zero oil in the throttle body or intake, but the engine still consumes large quantities of oil when driven hard.
- Careful inspection for oil leaks shows nothing.
- The rocker arm bolt holes are blind (they do not pierce the intake runner).
- The tail pipes are black and sooty. Washing the tailpipes has them very sooty again after a few aggressive driving sessions.
- A compression test revealed 195 PSI - 197 PSI across the eight cylinders.
- Not being able to access the crankshaft bolt, I was not able to perform a proper leak down test (unable to set piston to TDC). Instead I removed the rockers (to ensure the valves were closed) and performed the leakdown test. Escaping air is coming out of the crankcase (as would be expected) and not out of the intake or exhaust.

Questions:

- The cam being used closes the intake valve at 74 degrees ABDC (@ 0.006"). Considering this, does a compression of 195 PSI sound OK?

- Is it possible for decent/good compression test results, yet still suffer from rings that did not seal?

- I am planning on removing the valve springs to inspect the valve seals. The valve seals are Viton Blues and the heads were professionally assembled. I am doubtful it is the valve seals (but it does not hurt to verify). Does my check of the valve seals need to consist of anything more than ensuring all of the valve seals are correctly seated?

- Next steps?

 

i've redone several 416's recently that came from other shops with the same issue.all of those had improperly honed cylinders and the rings weren't sealing.

not saying that is your issue-but def could be-should do a leak down test

 

Thank you very much for the response!

I wonder if any of those "other shops" are the shop I bought my motor from! lol.

Regarding the leakdown test, without the piston being at TDC (but rocker arms removed) would a person get skewed results? I.e. as I moved around the car and did a leakdown on various cylinders (rockers removed), I would sometimes get a different result on the same cylinder, after the pistons had shuffled around a bit.

=== Leak down results ===

- Numbers shown are "leak down percent".

- "-->" is me moving to a different cylinder. Next set of results after a "-->" are after a different cylinder was tested.



Cylinder 1 (Cold)
12, 14, 13, 14, --> 26.5, 20, 21, 20, 21, --> 11, 10, 12.5, 11.5, 12, 10.5, 12.5, 10.5

Cylinder 2 (Cold)
10, 17.5, 20, 20, 20, 20, 19 --> 10.5, 11.5, 11.5, 11

Cylinder 3 (cold)
12, 11, 11, 9, 11, 11, 12

cylinder 4 (cold)
11, 12.5, 11, 12

Cylinder 5 (cold)
8.5, 8.5, 9.5, 8.5

Cylinder 6 (cold)
10, 11.5, 10, 11.5

Cylinder 7 (cold)
13.5, 11.5, 11, 11, 10

cylinder 8 (Cold)
10, 10, 9, 10

=========================

Cylinder 1 (Hot)
5, 6, 5, 10, 8

Cylinder 2 (Hot)
10, 10, 10, 10, 15

Cylinder 3 (Hot)
10, 12.5, 9, 16

Cylinder 4 (Hot)
14, 13.5, 15, 15, 13

Cylinder 5 (Hot)
15, 12, 12, 12.5

Cylinder 6 (Hot)
13, 13, 13

Cylinder 7 (Hot)
15, 15, 15

Cylinder 8 (Hot)
25, 20, 23, 18, 16, 18, 21, 18, 21, 18, 20

 

i think Scogin just cant make a "tight" ls3 block. there is many of us all with the same problem

 

Do you have the same motor as me?

I have been speaking with Scoggin about this issue on nearly a daily basis. If you have the same issue as me then perhaps that will help shine some light on what the issue actually is.

If you have contact information for anyone else with a similar motor and similar problem, please let me know. I will work with Scoggin Dickey to try and have this issue resolved for everyone.

 

are you kidding??? LOL

check your PM's fool!

 

Those leak down percents are horrible. You have found your source of oil consumption.

 

405HP_Z06

Your patience and help through all of this has been exceptional. :-)

I have been working with the vendor to discuss "next steps".