Removing DOD hardware & fitting a larger camshaft

[HSV-GTS-300]

The L76 6.0 engine is an LS2 engine block with good flowing L92 cylinder heads, a 90mm LS3 intake manifold and 40ish lb/hr LS7 injectors. There's lots of performance potential there in a Pontiac G8-GT, unfortunately in stock form it's also fitted with AFM or Displacement on Demand hardware.

This AFM hardware includes a tiny camshaft(200/208......0.472"/0.479") which has a different grind on cylinders 1, 4, 6 and 7 than the "normal" cylinders. Also fitted to cylinders 1, 4, 6 and 7 are De-Ac lifters , while the remaining cylinders use conventional lifters.

Those of you who are not concerned by powertrain warranty implications and wish to free up the performance potential of the 6.0 L76 may at some stage wish to remove the AFM Hardware and install a performance camshaft.

Here's the hardware involved :

[HSV-GTS-300]

1) Custom Camshaft. This will be the same as any normal LS1 type camshaft with a 3 bolt core from manufacturers such as Comp. Typically you'd wan't something with a split favouring the exhaust but with minimal overlap.
Something like below will normally achieve close to 450rwhp in this combo.
224@.050int, 230@.050exh
.581int, .590exh LSA 114
[Note PTV clearance must be checked in every case]




2) 12586481
Camshaft Sprocket
• Fits LS1, LS2 and LS6
• 4X camshaft gear
• 3-bolt design;
uses (3) bolts P/N 12556127

3) 12588670
LS2 Timing Chain Dampener
• Production LS2 Dampener
• For use with standard oil pumps
Re-use the 2x fasteners from the L76 chain tensioner.

[HSV-GTS-300]

4) Valve Spring Kit (typically dual spring) to match or exceed valve lift.
Example:
Patriot Gold .650" Lift Dual spring Kit PAT8401




5) Chrome Moly Pushrod Kit. Consult with your engine builder to determine the correct length of pushrods....this will depend upon the base circle of the chosen camshaft & other possible geometry changes such as head gasket thickness and any head milling.

Example:
Comp Cams CC7955-16 7.400" 5/16" 0.080"WT





6) Valve Lifters

Example:
12499225
LS Series Camshaft Lifter Kit
• Set of 16 lifters for LS series engines
• Same lifter used in LS2 and LS7

or

88958689
Racing Hydraulic Roller Lifter Kit
• As developed by GM Racing and GM Powertrain
• For use in Gen III and Gen IV engines where sustained
high rpm’s are typical
• Special reduced-mass internal components allow for
higher limiting speeds with aggressive camshaft designs
• Improved valvetrain dynamics and stability will improve
horsepower, and high rpm’s
• Tested to 8000 rpm in GM Racing applications
• Set of 16

[HSV-GTS-300]

7) 12610046
LS3, L92 Head Gasket
• Single gasket, (2) required
• For LS3 and L92 engines
• .051" thick
• 4.080" max bore
• Standard LS bolt pattern

8) 17800568
Cylinder Head Bolt Kit
• Kit of 15 bolts for LS Series engines produced from
January 2004 and later
• Bolts are 5mm shorter than previous design
(2) required

or

ARP134-3610 Hex head bolt kit, 2004 & up LS1/LS6/LS2
(1) set per engine required.




9) 12558573
LS Series Header Gaskets Pair

[HSV-GTS-300]

10)
12570471 LS2 Valley Cover





Those 8x O rings underneath block off the previous oil supply from the L76 Lifter Oil Manifold Assembly to the Collapsible DOD Lifters. Some engine builders additionally like to tap threads into these galleries and plug them with (Qty 8) 1/8"NPT allen plugs.





11) PCV Hose - Dirty Air (as per LS2)
Part# for the LS2 dirty air hose is 12594779
It goes from the LS2 valley cover to the side of the intake manifold.




12) Plug (as per LS2)
Part# for the LS2 Plug is 12579145
The existing L76 PCV outlet on the drivers side rear valve cover needs to be plugged.



Plug....Bottom left in this pic.



13) 17803305
Lifter Guide Kit
• Includes (4x) lifter guides and (4x) bolts
• Makes for quick and easy cam swaps without having to
remove the intake manifold, valley plate or heads
• Works in Gen III and IV applications (except with AFM)

or

LS2 Lifter Guides 12595365 (Qty 4 req).




14)
12557840
Crankshaft (Harmonic Balancer) Bolt

[HSV-GTS-300]

Additional consideration should be given to the DOD oiling system.
The L76 oil pump displaces 1.24"/rev compared to non-DOD 6.0 engines (LS2 and L98) which have 0.95"/rev oil pumps.

There is also a DOD specific oil pressure relief valve inside the oil pan. When main oil pressure exceeds 55psi this relief valve exhausts excess oil to the sump.

[HSV-GTS-300]

Dyno Sim Results (flywheel HP)

Yellow = 10.9 CR .......Cam 224/230 .581/.590 112 [FWHP]
Blue = 10.9 CR .......Cam 224/230 .581/.590 112 [TQ]
Red = 10.9 CR .......Cam 220/220 .581/.581 112 [FWHP]
Green = 10.9 CR .......Cam 220/220 .581/.581 112 [TQ]

10.9 CR is L92 heads milled 0.030" on a 6.0 block.




Yellow = 10.4 CR .......Cam 224/230 .581/.590 112 [FWHP]
Blue = 10.4 CR .......Cam 224/230 .581/.590 112 [TQ]
Red = 10.4 CR .......Cam 220/220 .581/.581 112 [FWHP]
Green = 10.4 CR .......Cam 220/220 .581/.581 112 [TQ]

10.4 CR is stock L92 heads on a 6.0 block.




Real world RWHP results in a 2006 GTO
LS2 6.0 Block, L92 heads, L76 car intake.
Cam 224/230 .581/.590 114
CR 10.4 (unmilled, untouched L92 heads)

[mrgto]

Nice info.

[avon001]

thanks champ!


I would assume this would apply to ls3 engines as well....

[HSV-GTS-300]

Originally posted by avon001
thanks champ!

I would assume this would apply to ls3 engines as well....

Nope the LS3 does not have DOD hardware fitted.

(Think of the LS3 as a 6.0 L98 thats been bored out .065" and you got it). L98 as per whats in the Holden VE.

(Except the LS3 has a half decent camshaft .551 lift).


http://en.wikipedia.org/wiki/GM_LS_engine#LS3

[scooter k]

What needs to be done to the oil pressure relief in the pan after cam and lifter swap? I've disable my dod on a L76 silverado. I did the same as described. My oil pressure has increased, runs 40-55.
Should I leave it alone?

[HSV-GTS-300]

Originally posted by scooter k
What needs to be done to the oil pressure relief in the pan after cam and lifter swap? I've disable my dod on a L76 silverado. I did the same as described. My oil pressure has increased, runs 40-55.
Should I leave it alone?

The Vortec L76 truck engine is a little different to the L76 found in the cars. The Vortec has displacement on demand and VVT. The L76 car engine only has the DOD.

Here's all the info I have on the oil pressure relief inside the oilpan of a Pontiac G8 L76 engine.



Unless you specifically want oil pressure above 55 psi its probably best to leave the relief valve alone IMO.

[scooter k]

The lubrication chart looks the same as the one I have for my truck. I didn't know for sure if I needed to do anything or not? Chevrolet had recent issues with oil pumps and I was planning on changing my cam again and thought I do the oil pump also. Just trying to see if I needed to change the relief valve.

[HSV-GTS-300]

Originally posted by scooter k
The lubrication chart looks the same as the one I have for my truck. I didn't know for sure if I needed to do anything or not? Chevrolet had recent issues with oil pumps and I was planning on changing my cam again and thought I do the oil pump also. Just trying to see if I needed to change the relief valve.

Did you retain use of the VVT system when you changed cams ?

[scooter k]

No I didn't. Since the cam selection is small with VVT I opted to go with a three bolt cam and gear. I've changed the cam once but have found a different one I would like to try so I'm changing it again. May also change the oil pump and timing chain. I have seen two that have locked up the oil pump. I also have a buddy with a trailblazer ss with the LS2 that is heavily modded, that broke the timing chain. It was a mess. He with a Katech chain and got me wondering if I should do the same. That is the first chain I have heard of breaking.

[HSV-GTS-300]

I haven't heard of oil pumps locking up or LS2 chains breaking.

The DOD engines all seem to be fitted with oil pumps of about 20% greater flowrate compared to equivalent non-DOD engines.
So your stock oil pump will be a different part number to a stock LS2 pump for example.

The LS2 chains were beefed up versions of the old LS1 chain and were supposedly heaps stronger. Just watch and make sure that if you do get a stronger chain that they give you the correct cam gear to suit. Some vendors have been sending out LS1 double roller sets to Gen 4 customers, LS1 cam gears dont have the cam timing lumps.
JP Performance show 3 different sets for Gen4.
http://www.speedinc.com/cont.cfm?cid=C0000712

I also read somewhere that if you change the cam gear (as you've done, 1 bolt to 3 bolt) then you should also change the browny coloured chain tensioner back to the 2005 style LS2 black chain damper.
It's something to do with harmonics/the subtle difference in the gear teeth.

[scooter k]

I work at a Chevrolet dealership and I personally have seen two
oil pump that locked up. Also have a bulletin out on them. I didn't know for sure on the tensioner so I left the one that it came with in there. Will a LS2 pump work since I'm not running dod or VVT?

[HSV-GTS-300]

Originally posted by scooter k
I work at a Chevrolet dealership and I personally have seen two
oil pump that locked up. Also have a bulletin out on them. I didn't know for sure on the tensioner so I left the one that it came with in there. Will a LS2 pump work since I'm not running dod or VVT?

I'm interested in the bulletin. Can you send me a copy or the bulletin number ? I've got a new 6.0 L76 crate here that I need to mod. It probably has the same oil pump you're talking about.

There's a good post somewhere on LS1tech.com about the tensioner change.

Yes an LS2 pump will work. Here in Oz we get a 6.0 L98 which is an L76 without DOD gear fitted. It has the LS2 pump.

[scooter k]

--------------------------------------------------------------------------------

#PIP4158: Low Oil Pressure Or Siezed Oil Pump - keywords 07 08 5.3 6.0 6.2 engine knock L76 L92 LC9 LH6 LS4 noise tick - (Jun 25, 2007)


Subject: Low Oil Pressure or Seized Oil Pump


Models: 2007-2008 Cadillac Escalade

2007-2008 Avalanche, Chevrolet Express, Silverado, Suburban, Tahoe, Trailblazer

2007-2008 GMC Savana, Sierra, Yukon

Vehicles equipped with aluminum block engines RPO codes L76 L92 LC9 LH6 LS4




--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
The customer concern may be low oil pressure, no oil pressure, or engine noise.

Recommendation/Instructions:
Complete the current diagnostic for any diagnostic trouble codes or symptoms found. If a customer concern of engine noise has been verified, and low oil pressure has been found, replace the oil pump, flush the oil cooler lines, clean the oil pan, and change the oil and filter.

It is possible for the oil pump to seize, and start to work again when the engine cools down. Evaluate all customer concerns of low oil pressure closely, and replace oil pumps as necessary.

Note: If an engine noise is noticed after replacing the

[HSV-GTS-300]

Awesome thanks.
My L76 oil pump will now be joining the DOD gear in the trash can.

I was already hesitant to use it because it's a high volume pump and I'll be using the Holden front sump oilpan......total circ oil volume 6 litres.
Some guys here have managed to pump the sump dry.
(Burnout up a hill = Kaboom)

[scooter k]

I've heard the same thing about high volume pumping the pan dry. I think I'll go with a melling pump with stock spring.
If you have the link to the ls1 tech with timing chain deal send it to me please.

[HSV-GTS-300]

Originally posted by scooter k
If you have the link to the ls1 tech with timing chain deal send it to me please.

I spent about an hour searching for that thread about reverting to the black dampener. It was from maybe 12 months or more ago, LS2 in a TBSS. I searched damper,dampner,dampener,tensioner, the 2 different part numbers......I cannot find it.

There are a few other threads in there about broken chains, vibrations,harmonics etc for LS2 cam chains tho.

[scooter k]

I just had a LS2 apart on a TBSS and it had the black chain dampner. I have only seen the spring loaded tensioner like I have on mine in the newer gen4 engines. I guess I have only had two 5.3's and mine own 6.0 apart on the newer engines and they all had the tensioner with spring.

[scooter k]

Anyway what do you do for a living? What is the time difference between us? It's 9 PM here right now

[HSV-GTS-300]

Originally posted by scooter k
I just had a LS2 apart on a TBSS and it had the black chain dampner. I have only seen the spring loaded tensioner like I have on mine in the newer gen4 engines. I guess I have only had two 5.3's and mine own 6.0 apart on the newer engines and they all had the tensioner with spring.

I think the black damper came with the 05 LS2's and was on all the 3 bolt cam versions.
The LS7 had a similar but thinner damper.....might be good for running double roller chains without the need to space the oilpump too.
The first I saw the tall thin browny tensioner was on 06+ single bolt cam engines.

I don't have a regular job. I work from home selling car parts and do a couple other ad-hoc jobs as required. 12:30pm Wednesday afternoon here now.

[scooter k]

So which one do I need to run? I bought the black dampner but never put it in.

[HSV-GTS-300]

I'd run the black dampener with a 3 bolt cam gear.

[scooter k]

Not for sure which oil pump to run. My pressure relief in the pan exhausts oil pressure when it's above 55 psi. If I go with a higher pressure pump it will just exhaust to the pan. I not for sure about the high volume but don't want to suck the pan dry. I know I don't want to use the stock one with all the problems they've had.
I'm wondering about changing the pressure relief in the pan but not for sure which one to use and then go with a different pump. From what I can see they are limiting oil pressure to the upper section of engine for the DOD lifters. I don't have them so I shoud be ok to change the relief in the pan.

[HSV-GTS-300]

Looks to me like the extra DOD relief valve in the pan is there to protect the lifter oil manifold assembly or the solenoid valves within.
If you throw away the DOD lifters and the LOMA and go with LS2 versions of each.......then remove/blank/adjust the relief to disable it.
Go with an LS2 style oilpump.....standard volume, or increased pressure if you like.

[avon001]

my guess would be that the pressure has to be limited for the dod system to work.

it seems to work on an oil pressure differential system.
ie. when turned off, solenoids are closed, and the bottom half of the lifter gets say (just a guess) 50psi pressure.
when solenoids activate, they send (again just a guess on the pressure) 55 psi to the top half of the lifter, therefore collapsing it.

they probably limited the pressure because of too much fluxuation of pressures above 55psi, making the system unreliable
(also backs up the high flow pump idea, more flow + lower pressure that is regulated = more stability)

so, if you dont have the soleniods in place, or never intend to switch them on, there sould be not problem.

if it was me, and i wanted to use one of the older low volume pumps, i would pull the pressure relif valve out and block the passage completely.
And if i ran into oil starvation problems, i would weld some wings to the side of the sump for a bit of extra volume.

i suppsoe its really a pity that GM didnt steal some toyota ideas and make the pressure relif valves into oil squirters for the bottom of the pistons

[HSV-GTS-300]

Chris Meagher, assistant chief engineer of small-block truck engines at GM.


"In support of cylinder deactivation is some very interesting choreography from things ranging from throttle valve modulation to active exhaust tuning, but it all starts with the additional job tasked to the lifters. "We disable the valves through a device called a switching lifter," explains Meagher. "This differs from a normal lifter in that there is an inner body and an outer body connected by a spring-loaded pin. For V-8 operation, the pin is fully expanded by the spring so the two pieces act as one and the lifter acts like a regular lifter. When we want to disable the valve operation, we deliver high-pressure oil to a groove in the lifter that leads to the outside end of the pin, forcing the pin to collapse the spring. Now the two parts of the lifter are free to move relative to one another and as the cam lobe pushes on the follower the inner portion of the lifter pushes against another spring at the top of the lifter and does not transfer force to the pushrod."

A look at the lifter cross-section reveals an elegant, yet simple design that has the potential to change the way we think about traditional pushrod engines. (Ironically, when DOD is working, it hinges on lifters that do not lift! Something we never thought we'd ever want.) In order for the switching lifter to work effectively, the engine needed a redesigned oiling system. Both iron and aluminum versions of the engine block have redesigned oil galleries to support DOD oiling requirements. Those oil galleries are supplied by a lifter oil manifold assembly (LOMA) located in the lifter valley of the engine. Under cylinder deactivation, the LOMA routes oil to the applicable lifters by means of four lifter oil solenoids, which are controlled by a new engine management controller. To supply the additional needs of the cylinder deactivation circuit, a higher capacity oil pump is fitted to the engine."

[HSV-GTS-300]

[scooter k]

WHAT HAPPENS IF I LEAVE THE RELIEF ALONE AND STILL REPLACED THE OIL PUMP WITH A LS2 STYLE. I'VE REMOVED THE VLOM AND LIFTERS ALREADY SO IT WON'T MATTER. THE ONLY THING IS THAT I WOULD STILL BE REGULATING OIL PRESSURE TO THE UPPER PART OF ENGINE. ANY HARM DONE THERE??

[avon001]

as long as your new pump can supply enough volume at 55psi you shouldnt have any problems.

also, the pump should have its own pressure reg (set at a higher pressure than the other one) which will prevent damage to the pump if you decide to remove the pressure reg in the oil pan.

[scooter k]

how about this oil pump? Do you think this will work?

http://cgi.ebay.com/ebaymotors/ws/eB...6778&viewitem=

[HSV-GTS-300]

Originally posted by scooter k
how about this oil pump? Do you think this will work?

http://cgi.ebay.com/ebaymotors/ws/eB...6778&viewitem=

Weren't you just telling us that the stock GM high volume oil pumps (DOD specific) sieze up. That one you linked us to is one of the suspect ones.

Pump specifications:

over 30% higher volume capacity pump than stock LS1/LS6/LS2 pump
displacement of 1.26 in3/rev (compared to the 0.95 in3/rev on the stock LS1/LS6/LS2 type pump)
8/9 gear set with thicker gear than LS1/LS6/LS2 stock pump

[scooter k]

Yes I was. But is this one a stock GM one??

[HSV-GTS-300]

Originally posted by scooter k
Yes I was. But is this one a stock GM one??

I can't be 100% sure.
It certainly has the same specs as the DOD oil pumps

[scooter k]

I thought I should stay with the same specs for the pump. I don't know if a standard pump would work or not. The dod motors have a higher volume pump then non dod. My dod lifters are taken out but thought I would stay with the same style pump to be safe.

[HSV-GTS-300]

In Australia Holden used the L76 6.0 for awhile in 2006, it had the LOMA and DOD cam and DOD lifters. It used the 0.95" oil pump.
The DOD system was not activated.



Then they came out with a different 6.0 called the L98.......it was just the same L76 but with an LS2 valley plate, LS2 lifters and same L76 cam. It used the 0.95" oil pump.
I do not know what they did with the DOD oil relief valve in the pan tho.


The US Spec 2008+ G8-GT uses L76 with AFM Activated. It uses the 1.24" oil pump.

[scooter k]

What is the model and year? I can look on GM service information, it has some Holden vehicles on there. I don't know if they are the same in the US as you have there?

[scooter k]

I looked at it and you are right L98 in a Holden does not have a pressure relief in the pan. L76 does and looks the same as what I have. Since I don't have the dod you would think I would be ok with the other LS2 spec pump. Since I disabled the dod with what you outlined in this thread I have gained oil pressure. It runs 40 at idle and 55 higher up. Before it was 20-50.

[scooter k]

http://www.jegs.com/webapp/wcs/store...-1&showValue=1

http://www.jegs.com/webapp/wcs/store...-1&showValue=1


This one?

[HSV-GTS-300]

That Melling could be the one.

This one definately is.

#12586665

Standard volume GM oil pump for LS engines. Original equipment oil pump for the LS1, LS6, LS2, and LS3 engines. This pump is used on most current V8 LS engines that are not equipped with Active Fuel Management.

Technical Notes:

Standard Volume LS Oil Pump
By-Pass Spring Opens at 32-psi
Recommended Pump for Most LS Engines

[scooter k]

That melling pump is a new pump they are making for GEN3-4
5.3 and 6.2 L92 engines. Doesn't say anything about the L76 but I'm assuming this one would have the extra volume if you were running DOD. I haven't figured out yet if I need the extra volume since I'm not running DOD. Isn't a L76 block the same as a LS2.
The LS2 I had apart looked like it was set up for DOD at least block wise. It didn't have the right valley cover but had all the oil passages in the block. Of course it didn't have the right lifters to operate.

[HSV-GTS-300]

LS2 and L76 blocks are the same.
Casting number 12568952.

I don't know how many times I have to tell you to just get a standard volume LS2 oil pump.

[scooter k]

I don't think you told me that?
Sorry, I read through it again and I don't see where you recommend that. Didn't mean to piss you off.

[scooter k]

Sorry I see it now, my fault.

[HSV-GTS-300]

223/231 .610 .617 113 +4
From the Comp Cams LSr line of cams
Comp LSL lobes.
I: 13016R 273 223 147 .359” .610”
E: 13018R 281 231 154 .363” .617”

Untouched L92 heads.
6.0 block.

[Lloyd]

I emailed Comp Cams for in order to find a cam for my G8. They told me they do not have any cams for my car that they would suggest. I found a couple of sites that offered a stage 1 cam and they say they are custom grind. Vector Motor Sports and Livernois Motor Sports. Both are saying with head work, header/full exhaust, cam and tune I will see about 425-440 rwhp. (They do have stage 2 but would not suggest it to most people because the drivability is not good).
To me, 425-440 seems so low. I do not understand how rice burners can get 100HP from 1 liter all the time, yet V8's can not.

[HSV-GTS-300]

Originally Posted by Lloyd

I emailed Comp Cams for in order to find a cam for my G8. They told me they do not have any cams for my car that they would suggest. I found a couple of sites that offered a stage 1 cam and they say they are custom grind. Vector Motor Sports and Livernois Motor Sports. Both are saying with head work, header/full exhaust, cam and tune I will see about 425-440 rwhp. (They do have stage 2 but would not suggest it to most people because the drivability is not good).

The AFM lifters in the car L76 engine handicap its performance potential.
You will find that Comp and most aftermarket suppliers can offer both an AFM (DOD) cam and a non-DOD cam range.
You just have to commit to either ridding your engine of AFM hardware or keeping it and living with a compromised cam solution.

Sounds like you need to discuss your requirements with someone who can spec you a cam to suit. I'll PM you info for the guy you need to speak with.

[towbar]

I am new to this site, and I very much appreciate your contributions on this topic. Info on the L76 engines has been pretty scarce.

I recently bought a L76 crate engine from Aus which I fitted with a Camaro LS1 sump. I don't intend to modify the engine until the car is up and running.

Just a couple of questions-

Am I likely to have an issue because the new sump has no relief valve?

Do you know if the non DOD lifters are factory LS2 lifters? If so, then maybe I don't need to replace all, just the DOD lifters when i do a cam.

Is there any real requirement to replace the L76 valley assembly other than to tidy things up?

Thanks, Jeremy

[HSV-GTS-300]

Originally Posted by towbar

I am new to this site, and I very much appreciate your contributions on this topic. Info on the L76 engines has been pretty scarce.
I recently bought a L76 crate engine from Aus which I fitted with a Camaro LS1 sump. I don't intend to modify the engine until the car is up and running.
Just a couple of questions-
Am I likely to have an issue because the new sump has no relief valve?
Do you know if the non DOD lifters are factory LS2 lifters? If so, then maybe I don't need to replace all, just the DOD lifters when i do a cam.
Is there any real requirement to replace the L76 valley assembly other than to tidy things up?
Thanks, Jeremy

Welcome Jeremy,
There's a little confusion about the oilpumps fitted to the L76 crate engines that became available in Australia. Most people are saying the 2006 L76 engines didn't have the high volume oilpump but did have the AFM relief valve inside the pan.
The AFM relief valve is only there to protect the lifter oil manifold assembly from over-pressure. To be safe its probably best to replace the LOMA with the LS2 valley cover and then you'll have no concern about the missing relief valve and you will have ridded yourself of a gang of oil solenoids that could begin to leak internally at any time.
Yes there's 8 normal LS lifters the same as currently used for replacements in LS1/LS2/LS3/LS6 and standard factory fit in LS7 (GM 12499225 is for a set of 16). You would only need to put 8 new LS lifters in.

[towbar]

Thanks
That's interesting. Apparently mine is a 2006. I guess I will find out about the pump when I do the cam. I see your point on the LOMA, better to be safe than sorry.

Do I understand correctly that the L76 does not have the plastic lifter guides fitted?

[HSV-GTS-300]

When you open it up have a look at the GM Part number on the front of the oil pump. Google the part number to find out if its a high volume (1.26"/rev) or standard volume (0.95"/rev).




L76 has 4 plastic lifter guides, but these guides are each for a mix of 2 AFM lifters and 2 normal lifters. Notice how the front cylinder and rear cylinder on this bank has different shaped lifter buckets to the centre pair of cylinders.

See here, L76 with AFM gear still installed


Difference between AFM and normal LS lifters



Here's an L76 after the AFM hardware has been removed.
Notice the LS2 style valley plate, GM 12570471.
It will now be fitted with 16 normal LS lifters & 4 new LS2 plastic lifter buckets.
4 x GM 12595365

[towbar]

Great info thanks. The differences with the L76 all seem pretty clear to me now. Upgrades are a little more of a hassle than usual, but there will be some serious rewards with a better cam.

I might also consider some new LS3 intake valves. I believe they are considerably lighter than the L92 ones, so they might go ok with uprated beehive springs (PAC maybe).

I will check my oil pump at cam time. Fingers crossed.

Thanks again.

[HSV-GTS-300]

Can't fault that plan.

[94guy]

will this ls3 part#12599296 work on the L99 motor for the conversion? this is what thunder racing sells for the dod delete.

[HSV-GTS-300]

Originally Posted by 94guy

will this ls3 part#12599296 work on the L99 motor for the conversion? this is what thunder racing sells for the dod delete.

Yes.
I can't see any difference between 12570471 & 12599296 except price.